Imaging

Interscalene brachial plexus anesthesia is commonly used for arthroscopic and open procedures of the shoulder. This regional anesthetic targets the trunks of the brachial plexus and anesthetizes the area about the shoulder and proximal arm. Its use may obviate the need for concomitant general anesthesia, potentially reducing the use of postoperative intravenous and oral pain medication. Furthermore, patients often bypass the acute postoperative anesthesia care unit and proceed directly to the ambulatory unit, permitting earlier hospital discharge. Previous reports in the literature have demonstrated higher rates of neurologic, cardiac, and pulmonary complications from this procedure; in particular, the incidence of pneumothorax was reported as high as 3%.¹ Techniques to localize the nerves, such as electrical nerve stimulation and, more recently, ultrasound guidance, have reduced these complication rates.^2,3 Successful administration of the block has been shown to result in satisfactory postoperative pain relief.² However, ultrasound-guided interscalene nerve blocks remain operator-dependent and complications may still occur.

We report a case of tension pneumothorax after arthroscopic rotator cuff repair and subacromial decompression with an ultrasound-guided interscalene block. Immediate recognition and treatment of this complication resulted in a good clinical outcome. The patient provided written informed consent for print and electronic publication of this case report. 

Case Report

A 56-year-old woman presented with 3 months of right shoulder pain after a fall. Examination was pertinent for weakness in forward elevation and positive rotator cuff impingement signs. She remained symptomatic despite a course of nonsurgical management that included cortisone injections and physical therapy. Magnetic resonance imaging of the shoulder showed a full-thickness supraspinatus tear with minimal fatty atrophy. After a discussion of her treatment options, she elected to undergo an arthroscopic rotator cuff repair with subacromial decompression. An evaluation by her internist revealed no pertinent medical history apart from obesity (body mass index, 36). Specifically, there was no reported history of chronic obstructive pulmonary disease or asthma. She denied any prior cigarette smoking.

The patient was evaluated by the regional anesthesia team and was classified as a class 2 airway. An interscalene brachial plexus block was performed using a 2-inch, 22-gauge needle inserted into the interscalene groove. Using an out-of-plane technique under direct ultrasound guidance, 30 mL of 0.52% ropivacaine was injected. The block was considered successful, and no complications, such as resistance, paresthesias, pain, or blood on aspiration, were noted during injection. The patient had no complaints of chest pain or shortness of breath immediately afterward, and all vital signs were stable throughout the procedure.

The patient was brought to the operating room and placed in the beach-chair position. Induction for general anesthesia was started 15 minutes after the regional anesthetic, with 2 intubation attempts necessary because of poor airway visualization. After placement of the endotracheal tube, breath sounds were noted to be equal bilaterally. The arthroscopic procedure consisted of double-row rotator cuff repair, subacromial decompression, and débridement of the glenohumeral joint for synovitis, using standard arthroscopic portals. There were no difficulties with trocar placement, and bleeding was minimal throughout the case. The total surgical time was 150 minutes and a pump pressure of 30 mm Hg was maintained during the arthroscopy.

Within the first 60 minutes of the start of the arthroscopic procedure, the patient was noted to be intermittently hypotensive with mean arterial pressure (MAP) ranging from the 30s to 130s mm Hg and pulse in the 70 to 80 beats/min range. FiO₂ in the 85% to 95% range was maintained throughout the procedure. During that time, 50 μg phenylephrine was administered on 4 separate occasions to maintain her blood pressure. The labile blood pressure was attributed by the anesthesiologist to the beach-chair position. During an attempted extubation upon conclusion of the surgery, the patient became hypotensive with MAP that ranged from the 40s to 60s mm Hg and tachycardic to 90 beats/min. The oxygen saturation was in the low 90s and tidal volume was poor. Absent lung sounds were noted on the right chest. An urgent portable chest radiograph showed a large right-sided tension pneumothorax with mediastinal shift (Figure 1). After an immediate general surgery consultation, a chest tube was placed in the operating room. The patient’s vital signs improved and a repeat chest radiograph revealed successful re-expansion of the lung (Figure 2). She was transferred to the acute postoperative anesthesia care unit and extubated in the intensive care unit later that day.

The patient’s chest tube was removed 2 days later and she was discharged home on hospital day 5 with a completely resolved pneumothorax. She was seen 1 week later in the office for a postoperative visit and reported feeling well without chest pain or shortness of breath.

Discussion

Interscalene brachial plexus anesthesia was first described by Winnie⁴ in 1970. This block targets the trunks of the brachial plexus, which are enclosed in a fascial sheath between the anterior and middle scalene muscles. In this region lie several structures at risk: the phrenic nerve superficially and inferiorly; the carotid sheath located superficially and medially; the subclavian artery parallel to the trunks; and the cupula of the lung that lies deep and inferior to the anterior scalene muscle. Recognized complications of the block include vocal hoarseness, Horner syndrome, and hemidiaphragmatic paresis caused by the temporary blockade of the ipsilateral recurrent laryngeal nerve, stellate ganglion, and phrenic nerve, in that order.⁵ Use of the interscalene block has been associated with minimal risk for pneumothorax, because the needle entry point is superior and directed away from the lung pleura.⁶ This is in contrast to the more inferiorly placed supraclavicular block, located in closer proximity to the lung cupula.⁵

Two different approaches are commonly used during ultrasound-guided nerve blocks. The in-plane approach generates a long-axis view of the needle by advancing the needle parallel with the long axis of the ultrasound probe. While this allows direct visualization of the needle tip, it requires deeper needle insertion from lateral to medial, causing puncture of the middle scalene muscle that may increase patient discomfort and risk nerve injury within the muscle.⁷ The out-of-plane approach used on our patient involves needle insertion parallel to the brachial plexus, but along the short axis of the ultrasound probe. Although this permits the operator to assess the periphery of the nerve, it may lead to poor needle-tip visualization during the procedure. As a result, operators often use a combination of tissue disturbance and “hydrolocation,” in which fluid is injected to indicate the needle-tip location.^8,9

Tension pneumothorax represents the accumulation of air in the pleural space that leads to impaired pulmonary and cardiac function. It is often caused by disruption or puncture of the parietal or visceral pleura, creating a connection between the alveoli and pleural cavity. The gradual buildup of air in the pleural cavity results in increased intrapleural pressure, which compresses and ultimately collapses the ipsilateral lung. Venous compression restricts blood return to the heart and reduces cardiac output. Clinical manifestations include dyspnea, hypoxemia, tachycardia, and hypotension.¹⁰ Multiple techniques were developed to better localize the brachial plexus while reducing injury to nearby structures, including the lung. These include eliciting needle paresthesias, electrical nerve stimulation, and ultrasound guidance. While nerve stimulation was once the gold standard for brachial plexus localization, ultrasound guidance has gained in popularity because of its noninvasive nature and dynamic capability to identify nerves and surrounding structures.¹¹ Perlas and colleagues¹² determined the sensitivity of needle paresthesias and nerve stimulation to be 38% and 75%, respectively, in cases in which plexus localization had been confirmed by ultrasound.

Several studies have reported on the efficacy of interscalene nerve block with either nerve stimulation or ultrasound guidance in the setting of shoulder surgery.^2,3 Bishop and colleagues³ reviewed 547 patients who underwent interscalene regional anesthesia with nerve stimulation for both arthroscopic and open-shoulder procedures. They reported a 97% success rate and 12 (2.3%) minor complications, including sensory neuropathy and complex regional pain syndrome. There were no cases of pneumothorax, cardiac events, or other major complications.³ In a prospective study of 1319 patients, Singh and colleagues² reported a 99.6% success rate using ultrasound-guided interscalene blocks for their shoulder surgeries. A total of 38 adverse events (2.88%) were identified: 14 transient neurologic events, including ear numbness, digital numbness, and brachial plexitis; 1 case of intraoperative bradycardia, and 2 cancellations after the block for chest pain and flank pain, which yielded negative cardiac workups. Other complications included postoperative emergency room visits and hospital admissions for reasons unrelated to the block.² Interscalene regional anesthesia, therefore, provides effective anesthesia for shoulder surgery with low complication rates.

Pneumothorax after ultrasound-guided interscalene block has rarely been reported.^13,14 In a review of 144 ultrasound-guided indwelling interscalene catheter placements, a 98% successful block rate with a single complication of small pneumothorax after total shoulder arthroplasty was reported.¹³ Mandim and colleagues¹⁴ reported a case of pneumothorax in a smoker who underwent an ultrasound-guided brachial plexus block prior to open reduction and internal fixation of an ulnar fracture. While the patient was asymptomatic and vital signs remained stable during the procedure, the patient complained postoperatively of chest pain with hypoxia, tachycardia, and hypotension. A chest radiograph confirmed an ipsilateral pneumothorax, and the patient was treated successfully with chest-tube placement. The authors attributed this complication to a higher pleural dome resulting from a hyperinflated lung caused by chronic smoking. Our patient reported no history of smoking and her preoperative chest radiograph had no evidence of lung disease.

In contrast, several cases of pneumothorax after shoulder surgery have been reported in the absence of nerve block. Oldman and Peng¹ reported a 41-year-old nonsmoker who underwent arthroscopic labral repair and subacromial decompression. The preoperative nerve block was cancelled, and the patient received general endotracheal anesthesia alone. Fifty minutes after the case, the patient developed chest pain and hypoxia. A chest radiograph showed a small pneumothorax that was managed conservatively. The pneumothorax was attributed to spontaneous rupture of a preexisting lung bulla, suggesting that blocks are not always the cause of this complication. Furthermore, Dietzel and Ciullo¹⁵ reported 4 cases of spontaneous pneumothorax within 24 hours of uncomplicated arthroscopic shoulder procedures under general anesthesia in the lateral decubitus position. The patient ages ranged from 22 to 38 years, and medical histories were all significant for preexisting lung disease, remote history of pneumonia, and heavy smoking. Three of the patients experienced symptoms at home the day after surgery. The authors concluded that these cases were likely caused by rupture of blebs or bullae from underlying lung disease; these ruptured blebs or bullae are difficult to detect and usually located in the upper lung. The pressure gradient from the positive pressure of anesthesia and the ipsilateral upper lung is thought to be highest in the lateral decubitus position, increasing their chance of rupture.¹⁵

Finally, Lee and colleagues¹⁶ described 3 patients aged 40 to 45 years who underwent uncomplicated subacromial decompression in the beach-chair position under general anesthesia. Significant shoulder, neck, and axillary swelling were noted after surgery, and a chest radiograph showed tension pneumothorax, subcutaneous emphysema, and pneumomediastinum. The authors speculated that pressure in the subacromial space may become negative relative to atmospheric pressure when the shaver and suction are running, drawing in air through other portals. When the suction is discontinued, fluid infusion may push air into the surrounding tissue, leading to subcutaneous emphysema, which may spread to the mediastinum.¹⁶ 

Conclusion 

Ultrasound-guided interscalene nerve blocks have successfully provided anesthesia for shoulder surgeries with low complication rates. Although the incidence of pneumothorax has decreased significantly with ultrasound guidance, the success of this procedure is highly operator-dependent. We present the case of an otherwise healthy patient without known pulmonary disease who developed a tension pneumothorax after the administration of ultrasound-guided regional and general anesthesia for arthroscopic shoulder surgery. Orthopedic surgeons and anesthesiologists must remain vigilant for pneumothorax during the perioperative period after shoulder surgery performed under interscalene regional aesthesia, particularly in the setting of hypotension, hypoxia, and/or tachycardia. Risk factors, such as history of smoking and preexisting lung disease, may predispose patients to the development of pneumothorax. Timely recognition and placement of a chest tube result in satisfactory clinical outcomes.

Interscalene brachial plexus anesthesia is commonly used for arthroscopic and open procedures of the shoulder. This regional anesthetic targets the trunks of the brachial plexus and anesthetizes the area about the shoulder and proximal arm. Its use may obviate the need for concomitant general anesthesia, potentially reducing the use of postoperative intravenous and oral pain medication. Furthermore, patients often bypass the acute postoperative anesthesia care unit and proceed directly to the ambulatory unit, permitting earlier hospital discharge. Previous reports in the literature have demonstrated higher rates of neurologic, cardiac, and pulmonary complications from this procedure; in particular, the incidence of pneumothorax was reported as high as 3%.¹ Techniques to localize the nerves, such as electrical nerve stimulation and, more recently, ultrasound guidance, have reduced these complication rates.^2,3 Successful administration of the block has been shown to result in satisfactory postoperative pain relief.² However, ultrasound-guided interscalene nerve blocks remain operator-dependent and complications may still occur.

We report a case of tension pneumothorax after arthroscopic rotator cuff repair and subacromial decompression with an ultrasound-guided interscalene block. Immediate recognition and treatment of this complication resulted in a good clinical outcome. The patient provided written informed consent for print and electronic publication of this case report. 

Case Report

A 56-year-old woman presented with 3 months of right shoulder pain after a fall. Examination was pertinent for weakness in forward elevation and positive rotator cuff impingement signs. She remained symptomatic despite a course of nonsurgical management that included cortisone injections and physical therapy. Magnetic resonance imaging of the shoulder showed a full-thickness supraspinatus tear with minimal fatty atrophy. After a discussion of her treatment options, she elected to undergo an arthroscopic rotator cuff repair with subacromial decompression. An evaluation by her internist revealed no pertinent medical history apart from obesity (body mass index, 36). Specifically, there was no reported history of chronic obstructive pulmonary disease or asthma. She denied any prior cigarette smoking.

The patient was evaluated by the regional anesthesia team and was classified as a class 2 airway. An interscalene brachial plexus block was performed using a 2-inch, 22-gauge needle inserted into the interscalene groove. Using an out-of-plane technique under direct ultrasound guidance, 30 mL of 0.52% ropivacaine was injected. The block was considered successful, and no complications, such as resistance, paresthesias, pain, or blood on aspiration, were noted during injection. The patient had no complaints of chest pain or shortness of breath immediately afterward, and all vital signs were stable throughout the procedure.

The patient was brought to the operating room and placed in the beach-chair position. Induction for general anesthesia was started 15 minutes after the regional anesthetic, with 2 intubation attempts necessary because of poor airway visualization. After placement of the endotracheal tube, breath sounds were noted to be equal bilaterally. The arthroscopic procedure consisted of double-row rotator cuff repair, subacromial decompression, and débridement of the glenohumeral joint for synovitis, using standard arthroscopic portals. There were no difficulties with trocar placement, and bleeding was minimal throughout the case. The total surgical time was 150 minutes and a pump pressure of 30 mm Hg was maintained during the arthroscopy.

Within the first 60 minutes of the start of the arthroscopic procedure, the patient was noted to be intermittently hypotensive with mean arterial pressure (MAP) ranging from the 30s to 130s mm Hg and pulse in the 70 to 80 beats/min range. FiO₂ in the 85% to 95% range was maintained throughout the procedure. During that time, 50 μg phenylephrine was administered on 4 separate occasions to maintain her blood pressure. The labile blood pressure was attributed by the anesthesiologist to the beach-chair position. During an attempted extubation upon conclusion of the surgery, the patient became hypotensive with MAP that ranged from the 40s to 60s mm Hg and tachycardic to 90 beats/min. The oxygen saturation was in the low 90s and tidal volume was poor. Absent lung sounds were noted on the right chest. An urgent portable chest radiograph showed a large right-sided tension pneumothorax with mediastinal shift (Figure 1). After an immediate general surgery consultation, a chest tube was placed in the operating room. The patient’s vital signs improved and a repeat chest radiograph revealed successful re-expansion of the lung (Figure 2). She was transferred to the acute postoperative anesthesia care unit and extubated in the intensive care unit later that day.

The patient’s chest tube was removed 2 days later and she was discharged home on hospital day 5 with a completely resolved pneumothorax. She was seen 1 week later in the office for a postoperative visit and reported feeling well without chest pain or shortness of breath.

Discussion

Interscalene brachial plexus anesthesia was first described by Winnie⁴ in 1970. This block targets the trunks of the brachial plexus, which are enclosed in a fascial sheath between the anterior and middle scalene muscles. In this region lie several structures at risk: the phrenic nerve superficially and inferiorly; the carotid sheath located superficially and medially; the subclavian artery parallel to the trunks; and the cupula of the lung that lies deep and inferior to the anterior scalene muscle. Recognized complications of the block include vocal hoarseness, Horner syndrome, and hemidiaphragmatic paresis caused by the temporary blockade of the ipsilateral recurrent laryngeal nerve, stellate ganglion, and phrenic nerve, in that order.⁵ Use of the interscalene block has been associated with minimal risk for pneumothorax, because the needle entry point is superior and directed away from the lung pleura.⁶ This is in contrast to the more inferiorly placed supraclavicular block, located in closer proximity to the lung cupula.⁵

Two different approaches are commonly used during ultrasound-guided nerve blocks. The in-plane approach generates a long-axis view of the needle by advancing the needle parallel with the long axis of the ultrasound probe. While this allows direct visualization of the needle tip, it requires deeper needle insertion from lateral to medial, causing puncture of the middle scalene muscle that may increase patient discomfort and risk nerve injury within the muscle.⁷ The out-of-plane approach used on our patient involves needle insertion parallel to the brachial plexus, but along the short axis of the ultrasound probe. Although this permits the operator to assess the periphery of the nerve, it may lead to poor needle-tip visualization during the procedure. As a result, operators often use a combination of tissue disturbance and “hydrolocation,” in which fluid is injected to indicate the needle-tip location.^8,9

Tension pneumothorax represents the accumulation of air in the pleural space that leads to impaired pulmonary and cardiac function. It is often caused by disruption or puncture of the parietal or visceral pleura, creating a connection between the alveoli and pleural cavity. The gradual buildup of air in the pleural cavity results in increased intrapleural pressure, which compresses and ultimately collapses the ipsilateral lung. Venous compression restricts blood return to the heart and reduces cardiac output. Clinical manifestations include dyspnea, hypoxemia, tachycardia, and hypotension.¹⁰ Multiple techniques were developed to better localize the brachial plexus while reducing injury to nearby structures, including the lung. These include eliciting needle paresthesias, electrical nerve stimulation, and ultrasound guidance. While nerve stimulation was once the gold standard for brachial plexus localization, ultrasound guidance has gained in popularity because of its noninvasive nature and dynamic capability to identify nerves and surrounding structures.¹¹ Perlas and colleagues¹² determined the sensitivity of needle paresthesias and nerve stimulation to be 38% and 75%, respectively, in cases in which plexus localization had been confirmed by ultrasound.

Several studies have reported on the efficacy of interscalene nerve block with either nerve stimulation or ultrasound guidance in the setting of shoulder surgery.^2,3 Bishop and colleagues³ reviewed 547 patients who underwent interscalene regional anesthesia with nerve stimulation for both arthroscopic and open-shoulder procedures. They reported a 97% success rate and 12 (2.3%) minor complications, including sensory neuropathy and complex regional pain syndrome. There were no cases of pneumothorax, cardiac events, or other major complications.³ In a prospective study of 1319 patients, Singh and colleagues² reported a 99.6% success rate using ultrasound-guided interscalene blocks for their shoulder surgeries. A total of 38 adverse events (2.88%) were identified: 14 transient neurologic events, including ear numbness, digital numbness, and brachial plexitis; 1 case of intraoperative bradycardia, and 2 cancellations after the block for chest pain and flank pain, which yielded negative cardiac workups. Other complications included postoperative emergency room visits and hospital admissions for reasons unrelated to the block.² Interscalene regional anesthesia, therefore, provides effective anesthesia for shoulder surgery with low complication rates.

Pneumothorax after ultrasound-guided interscalene block has rarely been reported.^13,14 In a review of 144 ultrasound-guided indwelling interscalene catheter placements, a 98% successful block rate with a single complication of small pneumothorax after total shoulder arthroplasty was reported.¹³ Mandim and colleagues¹⁴ reported a case of pneumothorax in a smoker who underwent an ultrasound-guided brachial plexus block prior to open reduction and internal fixation of an ulnar fracture. While the patient was asymptomatic and vital signs remained stable during the procedure, the patient complained postoperatively of chest pain with hypoxia, tachycardia, and hypotension. A chest radiograph confirmed an ipsilateral pneumothorax, and the patient was treated successfully with chest-tube placement. The authors attributed this complication to a higher pleural dome resulting from a hyperinflated lung caused by chronic smoking. Our patient reported no history of smoking and her preoperative chest radiograph had no evidence of lung disease.

In contrast, several cases of pneumothorax after shoulder surgery have been reported in the absence of nerve block. Oldman and Peng¹ reported a 41-year-old nonsmoker who underwent arthroscopic labral repair and subacromial decompression. The preoperative nerve block was cancelled, and the patient received general endotracheal anesthesia alone. Fifty minutes after the case, the patient developed chest pain and hypoxia. A chest radiograph showed a small pneumothorax that was managed conservatively. The pneumothorax was attributed to spontaneous rupture of a preexisting lung bulla, suggesting that blocks are not always the cause of this complication. Furthermore, Dietzel and Ciullo¹⁵ reported 4 cases of spontaneous pneumothorax within 24 hours of uncomplicated arthroscopic shoulder procedures under general anesthesia in the lateral decubitus position. The patient ages ranged from 22 to 38 years, and medical histories were all significant for preexisting lung disease, remote history of pneumonia, and heavy smoking. Three of the patients experienced symptoms at home the day after surgery. The authors concluded that these cases were likely caused by rupture of blebs or bullae from underlying lung disease; these ruptured blebs or bullae are difficult to detect and usually located in the upper lung. The pressure gradient from the positive pressure of anesthesia and the ipsilateral upper lung is thought to be highest in the lateral decubitus position, increasing their chance of rupture.¹⁵

Finally, Lee and colleagues¹⁶ described 3 patients aged 40 to 45 years who underwent uncomplicated subacromial decompression in the beach-chair position under general anesthesia. Significant shoulder, neck, and axillary swelling were noted after surgery, and a chest radiograph showed tension pneumothorax, subcutaneous emphysema, and pneumomediastinum. The authors speculated that pressure in the subacromial space may become negative relative to atmospheric pressure when the shaver and suction are running, drawing in air through other portals. When the suction is discontinued, fluid infusion may push air into the surrounding tissue, leading to subcutaneous emphysema, which may spread to the mediastinum.¹⁶ 

Conclusion 

Ultrasound-guided interscalene nerve blocks have successfully provided anesthesia for shoulder surgeries with low complication rates. Although the incidence of pneumothorax has decreased significantly with ultrasound guidance, the success of this procedure is highly operator-dependent. We present the case of an otherwise healthy patient without known pulmonary disease who developed a tension pneumothorax after the administration of ultrasound-guided regional and general anesthesia for arthroscopic shoulder surgery. Orthopedic surgeons and anesthesiologists must remain vigilant for pneumothorax during the perioperative period after shoulder surgery performed under interscalene regional aesthesia, particularly in the setting of hypotension, hypoxia, and/or tachycardia. Risk factors, such as history of smoking and preexisting lung disease, may predispose patients to the development of pneumothorax. Timely recognition and placement of a chest tube result in satisfactory clinical outcomes.

Interscalene brachial plexus anesthesia is commonly used for arthroscopic and open procedures of the shoulder. This regional anesthetic targets the trunks of the brachial plexus and anesthetizes the area about the shoulder and proximal arm. Its use may obviate the need for concomitant general anesthesia, potentially reducing the use of postoperative intravenous and oral pain medication. Furthermore, patients often bypass the acute postoperative anesthesia care unit and proceed directly to the ambulatory unit, permitting earlier hospital discharge. Previous reports in the literature have demonstrated higher rates of neurologic, cardiac, and pulmonary complications from this procedure; in particular, the incidence of pneumothorax was reported as high as 3%.¹ Techniques to localize the nerves, such as electrical nerve stimulation and, more recently, ultrasound guidance, have reduced these complication rates.^2,3 Successful administration of the block has been shown to result in satisfactory postoperative pain relief.² However, ultrasound-guided interscalene nerve blocks remain operator-dependent and complications may still occur.

We report a case of tension pneumothorax after arthroscopic rotator cuff repair and subacromial decompression with an ultrasound-guided interscalene block. Immediate recognition and treatment of this complication resulted in a good clinical outcome. The patient provided written informed consent for print and electronic publication of this case report. 

Case Report

A 56-year-old woman presented with 3 months of right shoulder pain after a fall. Examination was pertinent for weakness in forward elevation and positive rotator cuff impingement signs. She remained symptomatic despite a course of nonsurgical management that included cortisone injections and physical therapy. Magnetic resonance imaging of the shoulder showed a full-thickness supraspinatus tear with minimal fatty atrophy. After a discussion of her treatment options, she elected to undergo an arthroscopic rotator cuff repair with subacromial decompression. An evaluation by her internist revealed no pertinent medical history apart from obesity (body mass index, 36). Specifically, there was no reported history of chronic obstructive pulmonary disease or asthma. She denied any prior cigarette smoking.

The patient was evaluated by the regional anesthesia team and was classified as a class 2 airway. An interscalene brachial plexus block was performed using a 2-inch, 22-gauge needle inserted into the interscalene groove. Using an out-of-plane technique under direct ultrasound guidance, 30 mL of 0.52% ropivacaine was injected. The block was considered successful, and no complications, such as resistance, paresthesias, pain, or blood on aspiration, were noted during injection. The patient had no complaints of chest pain or shortness of breath immediately afterward, and all vital signs were stable throughout the procedure.

The patient was brought to the operating room and placed in the beach-chair position. Induction for general anesthesia was started 15 minutes after the regional anesthetic, with 2 intubation attempts necessary because of poor airway visualization. After placement of the endotracheal tube, breath sounds were noted to be equal bilaterally. The arthroscopic procedure consisted of double-row rotator cuff repair, subacromial decompression, and débridement of the glenohumeral joint for synovitis, using standard arthroscopic portals. There were no difficulties with trocar placement, and bleeding was minimal throughout the case. The total surgical time was 150 minutes and a pump pressure of 30 mm Hg was maintained during the arthroscopy.

Within the first 60 minutes of the start of the arthroscopic procedure, the patient was noted to be intermittently hypotensive with mean arterial pressure (MAP) ranging from the 30s to 130s mm Hg and pulse in the 70 to 80 beats/min range. FiO₂ in the 85% to 95% range was maintained throughout the procedure. During that time, 50 μg phenylephrine was administered on 4 separate occasions to maintain her blood pressure. The labile blood pressure was attributed by the anesthesiologist to the beach-chair position. During an attempted extubation upon conclusion of the surgery, the patient became hypotensive with MAP that ranged from the 40s to 60s mm Hg and tachycardic to 90 beats/min. The oxygen saturation was in the low 90s and tidal volume was poor. Absent lung sounds were noted on the right chest. An urgent portable chest radiograph showed a large right-sided tension pneumothorax with mediastinal shift (Figure 1). After an immediate general surgery consultation, a chest tube was placed in the operating room. The patient’s vital signs improved and a repeat chest radiograph revealed successful re-expansion of the lung (Figure 2). She was transferred to the acute postoperative anesthesia care unit and extubated in the intensive care unit later that day.

The patient’s chest tube was removed 2 days later and she was discharged home on hospital day 5 with a completely resolved pneumothorax. She was seen 1 week later in the office for a postoperative visit and reported feeling well without chest pain or shortness of breath.

Discussion

Interscalene brachial plexus anesthesia was first described by Winnie⁴ in 1970. This block targets the trunks of the brachial plexus, which are enclosed in a fascial sheath between the anterior and middle scalene muscles. In this region lie several structures at risk: the phrenic nerve superficially and inferiorly; the carotid sheath located superficially and medially; the subclavian artery parallel to the trunks; and the cupula of the lung that lies deep and inferior to the anterior scalene muscle. Recognized complications of the block include vocal hoarseness, Horner syndrome, and hemidiaphragmatic paresis caused by the temporary blockade of the ipsilateral recurrent laryngeal nerve, stellate ganglion, and phrenic nerve, in that order.⁵ Use of the interscalene block has been associated with minimal risk for pneumothorax, because the needle entry point is superior and directed away from the lung pleura.⁶ This is in contrast to the more inferiorly placed supraclavicular block, located in closer proximity to the lung cupula.⁵

Two different approaches are commonly used during ultrasound-guided nerve blocks. The in-plane approach generates a long-axis view of the needle by advancing the needle parallel with the long axis of the ultrasound probe. While this allows direct visualization of the needle tip, it requires deeper needle insertion from lateral to medial, causing puncture of the middle scalene muscle that may increase patient discomfort and risk nerve injury within the muscle.⁷ The out-of-plane approach used on our patient involves needle insertion parallel to the brachial plexus, but along the short axis of the ultrasound probe. Although this permits the operator to assess the periphery of the nerve, it may lead to poor needle-tip visualization during the procedure. As a result, operators often use a combination of tissue disturbance and “hydrolocation,” in which fluid is injected to indicate the needle-tip location.^8,9

Tension pneumothorax represents the accumulation of air in the pleural space that leads to impaired pulmonary and cardiac function. It is often caused by disruption or puncture of the parietal or visceral pleura, creating a connection between the alveoli and pleural cavity. The gradual buildup of air in the pleural cavity results in increased intrapleural pressure, which compresses and ultimately collapses the ipsilateral lung. Venous compression restricts blood return to the heart and reduces cardiac output. Clinical manifestations include dyspnea, hypoxemia, tachycardia, and hypotension.¹⁰ Multiple techniques were developed to better localize the brachial plexus while reducing injury to nearby structures, including the lung. These include eliciting needle paresthesias, electrical nerve stimulation, and ultrasound guidance. While nerve stimulation was once the gold standard for brachial plexus localization, ultrasound guidance has gained in popularity because of its noninvasive nature and dynamic capability to identify nerves and surrounding structures.¹¹ Perlas and colleagues¹² determined the sensitivity of needle paresthesias and nerve stimulation to be 38% and 75%, respectively, in cases in which plexus localization had been confirmed by ultrasound.

Several studies have reported on the efficacy of interscalene nerve block with either nerve stimulation or ultrasound guidance in the setting of shoulder surgery.^2,3 Bishop and colleagues³ reviewed 547 patients who underwent interscalene regional anesthesia with nerve stimulation for both arthroscopic and open-shoulder procedures. They reported a 97% success rate and 12 (2.3%) minor complications, including sensory neuropathy and complex regional pain syndrome. There were no cases of pneumothorax, cardiac events, or other major complications.³ In a prospective study of 1319 patients, Singh and colleagues² reported a 99.6% success rate using ultrasound-guided interscalene blocks for their shoulder surgeries. A total of 38 adverse events (2.88%) were identified: 14 transient neurologic events, including ear numbness, digital numbness, and brachial plexitis; 1 case of intraoperative bradycardia, and 2 cancellations after the block for chest pain and flank pain, which yielded negative cardiac workups. Other complications included postoperative emergency room visits and hospital admissions for reasons unrelated to the block.² Interscalene regional anesthesia, therefore, provides effective anesthesia for shoulder surgery with low complication rates.

Pneumothorax after ultrasound-guided interscalene block has rarely been reported.^13,14 In a review of 144 ultrasound-guided indwelling interscalene catheter placements, a 98% successful block rate with a single complication of small pneumothorax after total shoulder arthroplasty was reported.¹³ Mandim and colleagues¹⁴ reported a case of pneumothorax in a smoker who underwent an ultrasound-guided brachial plexus block prior to open reduction and internal fixation of an ulnar fracture. While the patient was asymptomatic and vital signs remained stable during the procedure, the patient complained postoperatively of chest pain with hypoxia, tachycardia, and hypotension. A chest radiograph confirmed an ipsilateral pneumothorax, and the patient was treated successfully with chest-tube placement. The authors attributed this complication to a higher pleural dome resulting from a hyperinflated lung caused by chronic smoking. Our patient reported no history of smoking and her preoperative chest radiograph had no evidence of lung disease.

In contrast, several cases of pneumothorax after shoulder surgery have been reported in the absence of nerve block. Oldman and Peng¹ reported a 41-year-old nonsmoker who underwent arthroscopic labral repair and subacromial decompression. The preoperative nerve block was cancelled, and the patient received general endotracheal anesthesia alone. Fifty minutes after the case, the patient developed chest pain and hypoxia. A chest radiograph showed a small pneumothorax that was managed conservatively. The pneumothorax was attributed to spontaneous rupture of a preexisting lung bulla, suggesting that blocks are not always the cause of this complication. Furthermore, Dietzel and Ciullo¹⁵ reported 4 cases of spontaneous pneumothorax within 24 hours of uncomplicated arthroscopic shoulder procedures under general anesthesia in the lateral decubitus position. The patient ages ranged from 22 to 38 years, and medical histories were all significant for preexisting lung disease, remote history of pneumonia, and heavy smoking. Three of the patients experienced symptoms at home the day after surgery. The authors concluded that these cases were likely caused by rupture of blebs or bullae from underlying lung disease; these ruptured blebs or bullae are difficult to detect and usually located in the upper lung. The pressure gradient from the positive pressure of anesthesia and the ipsilateral upper lung is thought to be highest in the lateral decubitus position, increasing their chance of rupture.¹⁵

Finally, Lee and colleagues¹⁶ described 3 patients aged 40 to 45 years who underwent uncomplicated subacromial decompression in the beach-chair position under general anesthesia. Significant shoulder, neck, and axillary swelling were noted after surgery, and a chest radiograph showed tension pneumothorax, subcutaneous emphysema, and pneumomediastinum. The authors speculated that pressure in the subacromial space may become negative relative to atmospheric pressure when the shaver and suction are running, drawing in air through other portals. When the suction is discontinued, fluid infusion may push air into the surrounding tissue, leading to subcutaneous emphysema, which may spread to the mediastinum.¹⁶ 

Conclusion 

Ultrasound-guided interscalene nerve blocks have successfully provided anesthesia for shoulder surgeries with low complication rates. Although the incidence of pneumothorax has decreased significantly with ultrasound guidance, the success of this procedure is highly operator-dependent. We present the case of an otherwise healthy patient without known pulmonary disease who developed a tension pneumothorax after the administration of ultrasound-guided regional and general anesthesia for arthroscopic shoulder surgery. Orthopedic surgeons and anesthesiologists must remain vigilant for pneumothorax during the perioperative period after shoulder surgery performed under interscalene regional aesthesia, particularly in the setting of hypotension, hypoxia, and/or tachycardia. Risk factors, such as history of smoking and preexisting lung disease, may predispose patients to the development of pneumothorax. Timely recognition and placement of a chest tube result in satisfactory clinical outcomes.

Spondylolysis, a defect in the pars interarticularis, is the single most common identifiable source of persistent low back pain in adolescent athletes.^1,2 The diagnosis of spondylolysis is confirmed by radiographic imaging.³ However, there is controversy regarding which imaging modality is preferred—specifically, which to use for first-line advanced imaging after plain radiographs are obtained.³ Single-photon emission computed tomography (SPECT) consistently has been shown to be the most sensitive modality, and it is considered the gold standard.^4-7 Patients with a positive SPECT scan are then routinely imaged with computed tomography (CT) for bone detail and staging of the pars defect.⁸ This imaging or diagnostic sequence yields organ-specific radiation doses (15-30 mSv) as much as 50-fold higher than those of plain radiography.⁹ Recent epidemiologic studies have shown that this organ dose results in an increased risk of cancer, especially in children.¹⁰

Diagnosis is crucial in early-stage lumbar spondylolysis, as osseous healing can occur with conservative treatment.^11,12 High signal change (HSC) in the pedicle or pars interarticularis (Figure 1) on fluid-specific (T2) magnetic resonance imaging (MRI) sequences has been shown to be important in the diagnosis of early spondylolysis and, subsequently, a good predictor of bony healing.^13,14 We conducted a study to determine the clinical and radiographic characteristics associated with the diagnosis of early or active spondylolysis.

Materials and Methods

The study was reviewed and approved by the local institutional review board. Using the International Classification of Diseases, Ninth Revision (ICD-9) diagnosis code for spondylolysis (756.11), we retrospectively identified patients (age, 12-21 years) from 2002–2011 billing data from a single specialty spine practice. Baseline data—including height, weight, sex, age, symptom duration, sporting activities, defect location, pain score, and previous treatments—were collected from a standardized patient intake questionnaire and office medical records. We also determined radiographic data, including level, laterality (right vs left, unilateral vs bilateral), presence of listhesis, and slip grade and percentage. CT scans were reviewed to confirm the spondylolysis diagnosis and to measure parameters described by Fujii and colleagues.¹⁵ These parameters include spondylolysis chronicity (early, progressive, terminal) (Figure 2), distance from defect to posterior margin of vertebral body, and defect angle relative to posterior margin of vertebral body. We also measured sagittal radiographic parameters, including pelvic incidence and lumbar lordosis.

Pars lesions were divided into active and inactive defects¹⁶ based on signal characteristics on either MRI or SPECT (Figure 3). Defects with a positive SPECT or HSC on T2 MRI were classified as active; all other defects were classified as inactive. All MRIs were reviewed by a radiologist, and any mention of HSC in the pedicle or pars of the corresponding level was considered positive. For the sake of accuracy, all MRIs were also reviewed by a spine surgeon. All CT measurements were done by 1 of 2 authors. Demographic, clinical, and radiographic characteristics were compared between patients with active defects and patients with inactive defects. Independent t tests and Fisher exact tests were used to compare continuous and categorical variables, respectively. Threshold P was set at .01 to account for the small sample size and multiple concurrent comparisons.

Results

Fifty-seven patients (29 males, 28 females) with a total of 108 pars defects (6 unilateral, 102 bilateral) were identified. Mean age was 14.64 years. Of the 108 defects, 49 were classified as active and 59 as inactive. SPECT results were available for 52 defects, MRI results for 85, and CT results for 76 (Table 1). There was no difference between the active and inactive groups in age (14.7 vs 14.6 years; P = .083), body mass index (24.2 vs 21.7 kg/m²; P = .034), symptom duration (236.3 vs 397.4 days; P = .016), lumbar lordosis (27.4° vs 32.1°; P = .097), pelvic incidence (59.0° vs 61.2°; P = .488), slip percentage (9.5% vs 14.2%; P = .034), and laterality (right vs left, P = .847; unilateral vs bilateral, P = .281) (Table 2). There was a significant difference between the active and inactive groups in sex (35 vs 19 males; P < .0001) and presence of listhesis (16 vs 35; P = .006) (Table 2).

Of the 49 active defects, 3 were graded as early, 10 as progressive, and 11 as terminal (Table 3). There was a statistically significant (P < .0001) difference between active and inactive lesions for each stage. Mean distance from posterior margin of the vertebral body was 0.57 mm and 0.68 mm for inactive and active lesions, respectively (P = .007). There was no significant difference (P = .294) in the posterior angle of the vertebral body and the defect between inactive (20.54°) and active (24.73°) lesions (Table 3).

Subanalysis by sex showed no difference in age (males, 16.4 years vs females, 18.7 years; P = .073), slip percentage (10.4% vs 13.4%; P = .168), or presence or absence of slip (25 vs 26; P > .99) (Table 4).

Discussion

Increasing MRI resolution combined with increasing concern about unnecessary radiation exposure has added to the attractiveness of MRI in the diagnosis of spondylolysis. Spondylolysis progresses on a continuum, starting with a stress reaction (early or active defect) and ending with either healing or nonunion of the pars defect (terminal defect) (Figure 4). Although risk factors for progression are not clearly defined, Fujii and colleagues¹⁵ showed that the reaction around the defect is the most important factor for osseous union. It would then make sense that the earlier the spondylolytic defect is identified, the higher the likelihood for union, especially with nonoperative treatment such as rest, activity restriction, and bracing.^12,17

There is a lack of consensus regarding MRI use in the diagnosis of spondylolysis. Masci and colleagues¹⁸ prospectively evaluated 50 defects in 39 patients using a 1.5-Tesla MRI scanner, concluded MRI is inferior to SPECT/CT, and recommended that SPECT remain the first-line advanced imaging modality. Conversely, Campbell and colleagues⁴ prospectively evaluated 40 defects in 22 patients using a 1.0-Tesla magnet and concluded that MRI can be used as an effective and reliable first-line advanced imaging modality. These are the only 2 prospective studies conducted within the past decade. Both were underpowered and used outdated technology (newer MRI scanners use 3.0-Tesla magnets). In addition, specific imaging characteristics (eg, edema in pars or pedicle on fluid-specific sequences) that suggest a positive finding—versus overt fracture on T1 MRI—have been recently emphasized. Neither Masci and colleagues¹⁸ nor Campbell and colleagues⁴ detailed what constituted a positive MRI finding. Although an adequately powered prospective study will provide a better analysis of the utility of MRI versus SPECT, such a study is costly and time-consuming. It is important to identify patient and lesion characteristics to help optimize the usefulness of MRI. It is also important to identify the subset of patients most likely to experience osseous healing of active defects,¹⁶ as this is the same subset of patients most likely to respond to nonoperative treatment.

We conducted the present study to identify any clinical or radiographic characteristics associated with the diagnosis of early or active spondylolysis. Almost equal numbers of active and inactive defects (49, 59) were identified. There were no differences in patient characteristics, including age, body mass index, and symptom duration. However, there was a significant sex difference—a relatively high proportion of males with active spondylolysis. This finding, which had been reported before,^16,19,20 is probably the result of several factors, including males’ lower lumbar spine bone mineral density²¹; their relatively less spinal flexibility, which affects the distribution of torsional loads on the spine²²; and their relatively greater participation in sports, especially sports involving high-velocity, torsional loading of the lumbar spine.²³ Studies are needed to delineate the extent to which sex influences the development and persistence of active spondylolytic lesions. Alternatively, a subanalysis revealed an age difference, between our female and male cohorts (18.7 vs 16.4 years), that may have contributed to the high proportion of males with active spondylolysis.

Although the groups’ difference in symptom duration was not significant, it was trending toward significance. As discussed, it could be explained that, along the continuum of disease, earlier defects are more active and either achieve fibrous or osseous union or become chronic and “burn out” to inactive lesions, potentially leading to a listhesis.²⁴ The listhesis association was higher in the inactive group than in the active group (P = .006). The difference in numbers of active and inactive defects at each stage (early, progressive, late) confirms this finding, with no inactive lesions in the early and progressive stages and many fewer active lesions in the terminal stage. Overall, presence of a spondylolisthesis on plain radiographs may obviate the need for SPECT or MRI, as it indicates an inactive chronic lesion—unless new symptoms are suspicious for reactivation or development of previously described adjacent-level pars defects.

No other radiographic parameters were found to be significant—consistent with findings of other studies.^2,5,16 Pelvic incidence has been shown to predict progression of spondylisthesis, but under our study parameters it appears not to be associated with development of a slip.

This study had several weaknesses. First, it was retrospective, and imaging parameters were inconsistent, as we included patients who underwent imaging at other facilities. Second, the timing of imaging was inconsistent. Ideally, the same sequence protocol would be used, and all imaging studies (MRI, SPECT, CT) would be performed within a specific period after the initial concern for a spondylolysis was raised. Last, not all patients underwent all 3 advanced imaging modalities; having all 3 would have allowed for a retrospective comparison of MRI and SPECT sensitivity in detecting spondylolysis. Such a comparison would have been interesting, though it was not the goal of this study.

With its technological improvements and lack of radiation exposure, MRI is becoming more attractive as a first-line advanced imaging modality. Although the superiority of MRI over SPECT is yet to be confirmed, clinical use of MRI in the evaluation of spondylolysis seems to be increasing. It is therefore important to characterize the spondylolytic defects that are readily detected with MRI.

Active or early juvenile spondylolysis appears to be associated with males and absence of an associated listhesis. These clinical and radiographic characteristics may be important in the identification of patients with higher potential for osseous healing after nonoperative treatment.

Spondylolysis, a defect in the pars interarticularis, is the single most common identifiable source of persistent low back pain in adolescent athletes.^1,2 The diagnosis of spondylolysis is confirmed by radiographic imaging.³ However, there is controversy regarding which imaging modality is preferred—specifically, which to use for first-line advanced imaging after plain radiographs are obtained.³ Single-photon emission computed tomography (SPECT) consistently has been shown to be the most sensitive modality, and it is considered the gold standard.^4-7 Patients with a positive SPECT scan are then routinely imaged with computed tomography (CT) for bone detail and staging of the pars defect.⁸ This imaging or diagnostic sequence yields organ-specific radiation doses (15-30 mSv) as much as 50-fold higher than those of plain radiography.⁹ Recent epidemiologic studies have shown that this organ dose results in an increased risk of cancer, especially in children.¹⁰

Diagnosis is crucial in early-stage lumbar spondylolysis, as osseous healing can occur with conservative treatment.^11,12 High signal change (HSC) in the pedicle or pars interarticularis (Figure 1) on fluid-specific (T2) magnetic resonance imaging (MRI) sequences has been shown to be important in the diagnosis of early spondylolysis and, subsequently, a good predictor of bony healing.^13,14 We conducted a study to determine the clinical and radiographic characteristics associated with the diagnosis of early or active spondylolysis.

Materials and Methods

The study was reviewed and approved by the local institutional review board. Using the International Classification of Diseases, Ninth Revision (ICD-9) diagnosis code for spondylolysis (756.11), we retrospectively identified patients (age, 12-21 years) from 2002–2011 billing data from a single specialty spine practice. Baseline data—including height, weight, sex, age, symptom duration, sporting activities, defect location, pain score, and previous treatments—were collected from a standardized patient intake questionnaire and office medical records. We also determined radiographic data, including level, laterality (right vs left, unilateral vs bilateral), presence of listhesis, and slip grade and percentage. CT scans were reviewed to confirm the spondylolysis diagnosis and to measure parameters described by Fujii and colleagues.¹⁵ These parameters include spondylolysis chronicity (early, progressive, terminal) (Figure 2), distance from defect to posterior margin of vertebral body, and defect angle relative to posterior margin of vertebral body. We also measured sagittal radiographic parameters, including pelvic incidence and lumbar lordosis.

Pars lesions were divided into active and inactive defects¹⁶ based on signal characteristics on either MRI or SPECT (Figure 3). Defects with a positive SPECT or HSC on T2 MRI were classified as active; all other defects were classified as inactive. All MRIs were reviewed by a radiologist, and any mention of HSC in the pedicle or pars of the corresponding level was considered positive. For the sake of accuracy, all MRIs were also reviewed by a spine surgeon. All CT measurements were done by 1 of 2 authors. Demographic, clinical, and radiographic characteristics were compared between patients with active defects and patients with inactive defects. Independent t tests and Fisher exact tests were used to compare continuous and categorical variables, respectively. Threshold P was set at .01 to account for the small sample size and multiple concurrent comparisons.

Results

Fifty-seven patients (29 males, 28 females) with a total of 108 pars defects (6 unilateral, 102 bilateral) were identified. Mean age was 14.64 years. Of the 108 defects, 49 were classified as active and 59 as inactive. SPECT results were available for 52 defects, MRI results for 85, and CT results for 76 (Table 1). There was no difference between the active and inactive groups in age (14.7 vs 14.6 years; P = .083), body mass index (24.2 vs 21.7 kg/m²; P = .034), symptom duration (236.3 vs 397.4 days; P = .016), lumbar lordosis (27.4° vs 32.1°; P = .097), pelvic incidence (59.0° vs 61.2°; P = .488), slip percentage (9.5% vs 14.2%; P = .034), and laterality (right vs left, P = .847; unilateral vs bilateral, P = .281) (Table 2). There was a significant difference between the active and inactive groups in sex (35 vs 19 males; P < .0001) and presence of listhesis (16 vs 35; P = .006) (Table 2).

Of the 49 active defects, 3 were graded as early, 10 as progressive, and 11 as terminal (Table 3). There was a statistically significant (P < .0001) difference between active and inactive lesions for each stage. Mean distance from posterior margin of the vertebral body was 0.57 mm and 0.68 mm for inactive and active lesions, respectively (P = .007). There was no significant difference (P = .294) in the posterior angle of the vertebral body and the defect between inactive (20.54°) and active (24.73°) lesions (Table 3).

Subanalysis by sex showed no difference in age (males, 16.4 years vs females, 18.7 years; P = .073), slip percentage (10.4% vs 13.4%; P = .168), or presence or absence of slip (25 vs 26; P > .99) (Table 4).

Discussion

Increasing MRI resolution combined with increasing concern about unnecessary radiation exposure has added to the attractiveness of MRI in the diagnosis of spondylolysis. Spondylolysis progresses on a continuum, starting with a stress reaction (early or active defect) and ending with either healing or nonunion of the pars defect (terminal defect) (Figure 4). Although risk factors for progression are not clearly defined, Fujii and colleagues¹⁵ showed that the reaction around the defect is the most important factor for osseous union. It would then make sense that the earlier the spondylolytic defect is identified, the higher the likelihood for union, especially with nonoperative treatment such as rest, activity restriction, and bracing.^12,17

There is a lack of consensus regarding MRI use in the diagnosis of spondylolysis. Masci and colleagues¹⁸ prospectively evaluated 50 defects in 39 patients using a 1.5-Tesla MRI scanner, concluded MRI is inferior to SPECT/CT, and recommended that SPECT remain the first-line advanced imaging modality. Conversely, Campbell and colleagues⁴ prospectively evaluated 40 defects in 22 patients using a 1.0-Tesla magnet and concluded that MRI can be used as an effective and reliable first-line advanced imaging modality. These are the only 2 prospective studies conducted within the past decade. Both were underpowered and used outdated technology (newer MRI scanners use 3.0-Tesla magnets). In addition, specific imaging characteristics (eg, edema in pars or pedicle on fluid-specific sequences) that suggest a positive finding—versus overt fracture on T1 MRI—have been recently emphasized. Neither Masci and colleagues¹⁸ nor Campbell and colleagues⁴ detailed what constituted a positive MRI finding. Although an adequately powered prospective study will provide a better analysis of the utility of MRI versus SPECT, such a study is costly and time-consuming. It is important to identify patient and lesion characteristics to help optimize the usefulness of MRI. It is also important to identify the subset of patients most likely to experience osseous healing of active defects,¹⁶ as this is the same subset of patients most likely to respond to nonoperative treatment.

We conducted the present study to identify any clinical or radiographic characteristics associated with the diagnosis of early or active spondylolysis. Almost equal numbers of active and inactive defects (49, 59) were identified. There were no differences in patient characteristics, including age, body mass index, and symptom duration. However, there was a significant sex difference—a relatively high proportion of males with active spondylolysis. This finding, which had been reported before,^16,19,20 is probably the result of several factors, including males’ lower lumbar spine bone mineral density²¹; their relatively less spinal flexibility, which affects the distribution of torsional loads on the spine²²; and their relatively greater participation in sports, especially sports involving high-velocity, torsional loading of the lumbar spine.²³ Studies are needed to delineate the extent to which sex influences the development and persistence of active spondylolytic lesions. Alternatively, a subanalysis revealed an age difference, between our female and male cohorts (18.7 vs 16.4 years), that may have contributed to the high proportion of males with active spondylolysis.

Although the groups’ difference in symptom duration was not significant, it was trending toward significance. As discussed, it could be explained that, along the continuum of disease, earlier defects are more active and either achieve fibrous or osseous union or become chronic and “burn out” to inactive lesions, potentially leading to a listhesis.²⁴ The listhesis association was higher in the inactive group than in the active group (P = .006). The difference in numbers of active and inactive defects at each stage (early, progressive, late) confirms this finding, with no inactive lesions in the early and progressive stages and many fewer active lesions in the terminal stage. Overall, presence of a spondylolisthesis on plain radiographs may obviate the need for SPECT or MRI, as it indicates an inactive chronic lesion—unless new symptoms are suspicious for reactivation or development of previously described adjacent-level pars defects.

No other radiographic parameters were found to be significant—consistent with findings of other studies.^2,5,16 Pelvic incidence has been shown to predict progression of spondylisthesis, but under our study parameters it appears not to be associated with development of a slip.

This study had several weaknesses. First, it was retrospective, and imaging parameters were inconsistent, as we included patients who underwent imaging at other facilities. Second, the timing of imaging was inconsistent. Ideally, the same sequence protocol would be used, and all imaging studies (MRI, SPECT, CT) would be performed within a specific period after the initial concern for a spondylolysis was raised. Last, not all patients underwent all 3 advanced imaging modalities; having all 3 would have allowed for a retrospective comparison of MRI and SPECT sensitivity in detecting spondylolysis. Such a comparison would have been interesting, though it was not the goal of this study.

With its technological improvements and lack of radiation exposure, MRI is becoming more attractive as a first-line advanced imaging modality. Although the superiority of MRI over SPECT is yet to be confirmed, clinical use of MRI in the evaluation of spondylolysis seems to be increasing. It is therefore important to characterize the spondylolytic defects that are readily detected with MRI.

Active or early juvenile spondylolysis appears to be associated with males and absence of an associated listhesis. These clinical and radiographic characteristics may be important in the identification of patients with higher potential for osseous healing after nonoperative treatment.

Spondylolysis, a defect in the pars interarticularis, is the single most common identifiable source of persistent low back pain in adolescent athletes.^1,2 The diagnosis of spondylolysis is confirmed by radiographic imaging.³ However, there is controversy regarding which imaging modality is preferred—specifically, which to use for first-line advanced imaging after plain radiographs are obtained.³ Single-photon emission computed tomography (SPECT) consistently has been shown to be the most sensitive modality, and it is considered the gold standard.^4-7 Patients with a positive SPECT scan are then routinely imaged with computed tomography (CT) for bone detail and staging of the pars defect.⁸ This imaging or diagnostic sequence yields organ-specific radiation doses (15-30 mSv) as much as 50-fold higher than those of plain radiography.⁹ Recent epidemiologic studies have shown that this organ dose results in an increased risk of cancer, especially in children.¹⁰

Diagnosis is crucial in early-stage lumbar spondylolysis, as osseous healing can occur with conservative treatment.^11,12 High signal change (HSC) in the pedicle or pars interarticularis (Figure 1) on fluid-specific (T2) magnetic resonance imaging (MRI) sequences has been shown to be important in the diagnosis of early spondylolysis and, subsequently, a good predictor of bony healing.^13,14 We conducted a study to determine the clinical and radiographic characteristics associated with the diagnosis of early or active spondylolysis.

Materials and Methods

The study was reviewed and approved by the local institutional review board. Using the International Classification of Diseases, Ninth Revision (ICD-9) diagnosis code for spondylolysis (756.11), we retrospectively identified patients (age, 12-21 years) from 2002–2011 billing data from a single specialty spine practice. Baseline data—including height, weight, sex, age, symptom duration, sporting activities, defect location, pain score, and previous treatments—were collected from a standardized patient intake questionnaire and office medical records. We also determined radiographic data, including level, laterality (right vs left, unilateral vs bilateral), presence of listhesis, and slip grade and percentage. CT scans were reviewed to confirm the spondylolysis diagnosis and to measure parameters described by Fujii and colleagues.¹⁵ These parameters include spondylolysis chronicity (early, progressive, terminal) (Figure 2), distance from defect to posterior margin of vertebral body, and defect angle relative to posterior margin of vertebral body. We also measured sagittal radiographic parameters, including pelvic incidence and lumbar lordosis.

Pars lesions were divided into active and inactive defects¹⁶ based on signal characteristics on either MRI or SPECT (Figure 3). Defects with a positive SPECT or HSC on T2 MRI were classified as active; all other defects were classified as inactive. All MRIs were reviewed by a radiologist, and any mention of HSC in the pedicle or pars of the corresponding level was considered positive. For the sake of accuracy, all MRIs were also reviewed by a spine surgeon. All CT measurements were done by 1 of 2 authors. Demographic, clinical, and radiographic characteristics were compared between patients with active defects and patients with inactive defects. Independent t tests and Fisher exact tests were used to compare continuous and categorical variables, respectively. Threshold P was set at .01 to account for the small sample size and multiple concurrent comparisons.

Results

Fifty-seven patients (29 males, 28 females) with a total of 108 pars defects (6 unilateral, 102 bilateral) were identified. Mean age was 14.64 years. Of the 108 defects, 49 were classified as active and 59 as inactive. SPECT results were available for 52 defects, MRI results for 85, and CT results for 76 (Table 1). There was no difference between the active and inactive groups in age (14.7 vs 14.6 years; P = .083), body mass index (24.2 vs 21.7 kg/m²; P = .034), symptom duration (236.3 vs 397.4 days; P = .016), lumbar lordosis (27.4° vs 32.1°; P = .097), pelvic incidence (59.0° vs 61.2°; P = .488), slip percentage (9.5% vs 14.2%; P = .034), and laterality (right vs left, P = .847; unilateral vs bilateral, P = .281) (Table 2). There was a significant difference between the active and inactive groups in sex (35 vs 19 males; P < .0001) and presence of listhesis (16 vs 35; P = .006) (Table 2).

Of the 49 active defects, 3 were graded as early, 10 as progressive, and 11 as terminal (Table 3). There was a statistically significant (P < .0001) difference between active and inactive lesions for each stage. Mean distance from posterior margin of the vertebral body was 0.57 mm and 0.68 mm for inactive and active lesions, respectively (P = .007). There was no significant difference (P = .294) in the posterior angle of the vertebral body and the defect between inactive (20.54°) and active (24.73°) lesions (Table 3).

Subanalysis by sex showed no difference in age (males, 16.4 years vs females, 18.7 years; P = .073), slip percentage (10.4% vs 13.4%; P = .168), or presence or absence of slip (25 vs 26; P > .99) (Table 4).

Discussion

Increasing MRI resolution combined with increasing concern about unnecessary radiation exposure has added to the attractiveness of MRI in the diagnosis of spondylolysis. Spondylolysis progresses on a continuum, starting with a stress reaction (early or active defect) and ending with either healing or nonunion of the pars defect (terminal defect) (Figure 4). Although risk factors for progression are not clearly defined, Fujii and colleagues¹⁵ showed that the reaction around the defect is the most important factor for osseous union. It would then make sense that the earlier the spondylolytic defect is identified, the higher the likelihood for union, especially with nonoperative treatment such as rest, activity restriction, and bracing.^12,17

There is a lack of consensus regarding MRI use in the diagnosis of spondylolysis. Masci and colleagues¹⁸ prospectively evaluated 50 defects in 39 patients using a 1.5-Tesla MRI scanner, concluded MRI is inferior to SPECT/CT, and recommended that SPECT remain the first-line advanced imaging modality. Conversely, Campbell and colleagues⁴ prospectively evaluated 40 defects in 22 patients using a 1.0-Tesla magnet and concluded that MRI can be used as an effective and reliable first-line advanced imaging modality. These are the only 2 prospective studies conducted within the past decade. Both were underpowered and used outdated technology (newer MRI scanners use 3.0-Tesla magnets). In addition, specific imaging characteristics (eg, edema in pars or pedicle on fluid-specific sequences) that suggest a positive finding—versus overt fracture on T1 MRI—have been recently emphasized. Neither Masci and colleagues¹⁸ nor Campbell and colleagues⁴ detailed what constituted a positive MRI finding. Although an adequately powered prospective study will provide a better analysis of the utility of MRI versus SPECT, such a study is costly and time-consuming. It is important to identify patient and lesion characteristics to help optimize the usefulness of MRI. It is also important to identify the subset of patients most likely to experience osseous healing of active defects,¹⁶ as this is the same subset of patients most likely to respond to nonoperative treatment.

We conducted the present study to identify any clinical or radiographic characteristics associated with the diagnosis of early or active spondylolysis. Almost equal numbers of active and inactive defects (49, 59) were identified. There were no differences in patient characteristics, including age, body mass index, and symptom duration. However, there was a significant sex difference—a relatively high proportion of males with active spondylolysis. This finding, which had been reported before,^16,19,20 is probably the result of several factors, including males’ lower lumbar spine bone mineral density²¹; their relatively less spinal flexibility, which affects the distribution of torsional loads on the spine²²; and their relatively greater participation in sports, especially sports involving high-velocity, torsional loading of the lumbar spine.²³ Studies are needed to delineate the extent to which sex influences the development and persistence of active spondylolytic lesions. Alternatively, a subanalysis revealed an age difference, between our female and male cohorts (18.7 vs 16.4 years), that may have contributed to the high proportion of males with active spondylolysis.

Although the groups’ difference in symptom duration was not significant, it was trending toward significance. As discussed, it could be explained that, along the continuum of disease, earlier defects are more active and either achieve fibrous or osseous union or become chronic and “burn out” to inactive lesions, potentially leading to a listhesis.²⁴ The listhesis association was higher in the inactive group than in the active group (P = .006). The difference in numbers of active and inactive defects at each stage (early, progressive, late) confirms this finding, with no inactive lesions in the early and progressive stages and many fewer active lesions in the terminal stage. Overall, presence of a spondylolisthesis on plain radiographs may obviate the need for SPECT or MRI, as it indicates an inactive chronic lesion—unless new symptoms are suspicious for reactivation or development of previously described adjacent-level pars defects.

No other radiographic parameters were found to be significant—consistent with findings of other studies.^2,5,16 Pelvic incidence has been shown to predict progression of spondylisthesis, but under our study parameters it appears not to be associated with development of a slip.

This study had several weaknesses. First, it was retrospective, and imaging parameters were inconsistent, as we included patients who underwent imaging at other facilities. Second, the timing of imaging was inconsistent. Ideally, the same sequence protocol would be used, and all imaging studies (MRI, SPECT, CT) would be performed within a specific period after the initial concern for a spondylolysis was raised. Last, not all patients underwent all 3 advanced imaging modalities; having all 3 would have allowed for a retrospective comparison of MRI and SPECT sensitivity in detecting spondylolysis. Such a comparison would have been interesting, though it was not the goal of this study.

With its technological improvements and lack of radiation exposure, MRI is becoming more attractive as a first-line advanced imaging modality. Although the superiority of MRI over SPECT is yet to be confirmed, clinical use of MRI in the evaluation of spondylolysis seems to be increasing. It is therefore important to characterize the spondylolytic defects that are readily detected with MRI.

Active or early juvenile spondylolysis appears to be associated with males and absence of an associated listhesis. These clinical and radiographic characteristics may be important in the identification of patients with higher potential for osseous healing after nonoperative treatment.

Osteochondromas are common benign bone tumors composed of a bony protrusion with an overlying cartilage cap.¹ This lesion constitutes 24% to 40% of all benign bone tumors, and the great majority arise from the metaphyseal region of long bones.² The scapula accounts for only 3% to 5% of all osteochondromas; however, this lesion is the most common benign bone tumor to involve the scapula.³

In contrast, cutaneous bronchogenic cyst of the scapula is an exceedingly rare pathology. The bronchogenic cyst is a congenital cystic mass lined by tracheobronchial structures and respiratory epithelium.⁴ These are most commonly located in the thorax, although numerous remote locations have also been described, including cutaneous cysts.⁵ The overall incidence of bronchogenic cysts is thought to be 1 in 42,000 to 1 in 68,000.⁶ There are only 15 case reports of cutaneous bronchogenic cysts in the scapular region.⁷

We report the case of a novel dual lesion of both an osteochondroma and a contiguous cutaneous bronchogenic cyst in the scapula. The patient’s guardian provided written informed consent for print and electronic publication of this case report.

Case Report

A 12-month-old boy presented to our clinic with the complaint of a mass over the left scapula. The mass was first noted incidentally several weeks earlier during bathing. Examination revealed a firm, subcutaneous, nontender mass measuring 1×2 cm located over the spine of the scapula. There were no overlying skin changes, and there was normal function of the ipsilateral upper extremity. Anteroposterior and lateral chest radiographs revealed no abnormality. Magnetic resonance imaging (MRI) showed an exostosis projecting from the scapular spine measuring 2×6×7 mm with an adjacent cystic mass measuring 5×8×9 mm that was thought to represent bursitis (Figure 1). The decision was made to observe the mass. 

The patient returned to clinic at age 31 months with a new complaint of scant drainage of serous fluid from a pinprick-sized hole located just superolateral to the scapular mass. The child’s mother reported daily manual expression of fluid from the mass via the hole, without which the mass would enlarge. There were no local or systemic signs of infection. A repeat MRI again revealed an exostosis with an adjacent cystic mass with interval enlargement of the cyst (Figure 2). At age 4.5 years, the decision was made to proceed with excision of the osteochondroma and adjacent cystic mass.

The mass was approached via a 2-cm incision designed to excise the tract to the skin. Dissection revealed a sinus tract connecting to a well-defined cystic sac. This sac was attached to the underlying exostosis. The exostosis and attached cyst were excised en bloc. The cyst was opened, revealing foul-smelling, cloudy white fluid that was sent for culture; the specimen was sent for pathology.

The fluid culture grew mixed flora, with no Staphylococcus aureus, group A streptococcus, or Pseudomonas aeruginosa identified. The pathologic examination identified bone with a cartilaginous cap, consistent with osteochondroma (Figure 3), as well as a cyst lined by respiratory epithelium with patchy areas of squamous epithelium and surrounding mucus glands, consistent with bronchogenic cyst (Figure 4). Figure 5 shows the contiguous nature of the 2 lesions.

The postoperative course was uneventful. The patient returned to full use of the left upper extremity and had resolution of all drainage. 

Discussion

Osteochondromas are thought to arise from aberrant growth of the epiphyseal growth plate cartilage. A small portion of the physis herniates past the groove of Ranvier and grows parallel to the normal physis with medullary continuity. This can occur idiopathically or, more rarely, secondary to an identified injury to the growth plate.¹

The formation of bronchogenic cysts is most often attributed to anomalous budding of the ventral foregut during fetal development,⁴ hence the alternative designation of these cysts as foregut cysts. An extrathoracic location of the cyst has been postulated to stem from 2 possible events: a preexisting cyst may migrate out of the thorax prior to closure of the sternal plates, or sternal plate closure may itself pinch off the cyst.^8,9 An alternative explanation is in situ metaplastic development of respiratory epithelium.¹⁰ When located near the skin, these cysts often drain clear fluid.¹¹

Scapular osteochondromas are known to cause various pathologies of the shoulder girdle, including snapping scapula syndrome, chest wall deformity, shoulder impingement, and bursa formation.^12-17 This case, however, is the first known finding of a scapular osteochondroma with a contiguous cutaneous bronchogenic cyst. A putative explanation for their co-occurrence is that local disturbances caused by one lesion stimulated the formation of the second. The direct connection between the bronchogenic cyst and the bone, as has been reported in 3 cases,^7,9,18 seems to favor this explanation. Definitive conclusions regarding any causal relationship are beyond the scope of this single case report.

Definitive management of bronchogenic cysts is complete excision, although the diagnosis is often not made until histopathologic examination has been completed.¹⁹ Osteochondromas are managed with observation unless they are symptomatic.² Malignant degeneration is a rare but documented occurrence in both lesions.^2,20

Conclusion

In approaching the pediatric patient with a cystic mass over the scapula, a cutaneous bronchogenic cyst may be included in the differential diagnosis. This lesion can occur in isolation or can be found with another pathology, such as osteochondroma, as reported here.

Osteochondromas are common benign bone tumors composed of a bony protrusion with an overlying cartilage cap.¹ This lesion constitutes 24% to 40% of all benign bone tumors, and the great majority arise from the metaphyseal region of long bones.² The scapula accounts for only 3% to 5% of all osteochondromas; however, this lesion is the most common benign bone tumor to involve the scapula.³

In contrast, cutaneous bronchogenic cyst of the scapula is an exceedingly rare pathology. The bronchogenic cyst is a congenital cystic mass lined by tracheobronchial structures and respiratory epithelium.⁴ These are most commonly located in the thorax, although numerous remote locations have also been described, including cutaneous cysts.⁵ The overall incidence of bronchogenic cysts is thought to be 1 in 42,000 to 1 in 68,000.⁶ There are only 15 case reports of cutaneous bronchogenic cysts in the scapular region.⁷

We report the case of a novel dual lesion of both an osteochondroma and a contiguous cutaneous bronchogenic cyst in the scapula. The patient’s guardian provided written informed consent for print and electronic publication of this case report.

Case Report

A 12-month-old boy presented to our clinic with the complaint of a mass over the left scapula. The mass was first noted incidentally several weeks earlier during bathing. Examination revealed a firm, subcutaneous, nontender mass measuring 1×2 cm located over the spine of the scapula. There were no overlying skin changes, and there was normal function of the ipsilateral upper extremity. Anteroposterior and lateral chest radiographs revealed no abnormality. Magnetic resonance imaging (MRI) showed an exostosis projecting from the scapular spine measuring 2×6×7 mm with an adjacent cystic mass measuring 5×8×9 mm that was thought to represent bursitis (Figure 1). The decision was made to observe the mass. 

The patient returned to clinic at age 31 months with a new complaint of scant drainage of serous fluid from a pinprick-sized hole located just superolateral to the scapular mass. The child’s mother reported daily manual expression of fluid from the mass via the hole, without which the mass would enlarge. There were no local or systemic signs of infection. A repeat MRI again revealed an exostosis with an adjacent cystic mass with interval enlargement of the cyst (Figure 2). At age 4.5 years, the decision was made to proceed with excision of the osteochondroma and adjacent cystic mass.

The mass was approached via a 2-cm incision designed to excise the tract to the skin. Dissection revealed a sinus tract connecting to a well-defined cystic sac. This sac was attached to the underlying exostosis. The exostosis and attached cyst were excised en bloc. The cyst was opened, revealing foul-smelling, cloudy white fluid that was sent for culture; the specimen was sent for pathology.

The fluid culture grew mixed flora, with no Staphylococcus aureus, group A streptococcus, or Pseudomonas aeruginosa identified. The pathologic examination identified bone with a cartilaginous cap, consistent with osteochondroma (Figure 3), as well as a cyst lined by respiratory epithelium with patchy areas of squamous epithelium and surrounding mucus glands, consistent with bronchogenic cyst (Figure 4). Figure 5 shows the contiguous nature of the 2 lesions.

The postoperative course was uneventful. The patient returned to full use of the left upper extremity and had resolution of all drainage. 

Discussion

Osteochondromas are thought to arise from aberrant growth of the epiphyseal growth plate cartilage. A small portion of the physis herniates past the groove of Ranvier and grows parallel to the normal physis with medullary continuity. This can occur idiopathically or, more rarely, secondary to an identified injury to the growth plate.¹

The formation of bronchogenic cysts is most often attributed to anomalous budding of the ventral foregut during fetal development,⁴ hence the alternative designation of these cysts as foregut cysts. An extrathoracic location of the cyst has been postulated to stem from 2 possible events: a preexisting cyst may migrate out of the thorax prior to closure of the sternal plates, or sternal plate closure may itself pinch off the cyst.^8,9 An alternative explanation is in situ metaplastic development of respiratory epithelium.¹⁰ When located near the skin, these cysts often drain clear fluid.¹¹

Scapular osteochondromas are known to cause various pathologies of the shoulder girdle, including snapping scapula syndrome, chest wall deformity, shoulder impingement, and bursa formation.^12-17 This case, however, is the first known finding of a scapular osteochondroma with a contiguous cutaneous bronchogenic cyst. A putative explanation for their co-occurrence is that local disturbances caused by one lesion stimulated the formation of the second. The direct connection between the bronchogenic cyst and the bone, as has been reported in 3 cases,^7,9,18 seems to favor this explanation. Definitive conclusions regarding any causal relationship are beyond the scope of this single case report.

Definitive management of bronchogenic cysts is complete excision, although the diagnosis is often not made until histopathologic examination has been completed.¹⁹ Osteochondromas are managed with observation unless they are symptomatic.² Malignant degeneration is a rare but documented occurrence in both lesions.^2,20

Conclusion

In approaching the pediatric patient with a cystic mass over the scapula, a cutaneous bronchogenic cyst may be included in the differential diagnosis. This lesion can occur in isolation or can be found with another pathology, such as osteochondroma, as reported here.

Osteochondromas are common benign bone tumors composed of a bony protrusion with an overlying cartilage cap.¹ This lesion constitutes 24% to 40% of all benign bone tumors, and the great majority arise from the metaphyseal region of long bones.² The scapula accounts for only 3% to 5% of all osteochondromas; however, this lesion is the most common benign bone tumor to involve the scapula.³

In contrast, cutaneous bronchogenic cyst of the scapula is an exceedingly rare pathology. The bronchogenic cyst is a congenital cystic mass lined by tracheobronchial structures and respiratory epithelium.⁴ These are most commonly located in the thorax, although numerous remote locations have also been described, including cutaneous cysts.⁵ The overall incidence of bronchogenic cysts is thought to be 1 in 42,000 to 1 in 68,000.⁶ There are only 15 case reports of cutaneous bronchogenic cysts in the scapular region.⁷

We report the case of a novel dual lesion of both an osteochondroma and a contiguous cutaneous bronchogenic cyst in the scapula. The patient’s guardian provided written informed consent for print and electronic publication of this case report.

Case Report

A 12-month-old boy presented to our clinic with the complaint of a mass over the left scapula. The mass was first noted incidentally several weeks earlier during bathing. Examination revealed a firm, subcutaneous, nontender mass measuring 1×2 cm located over the spine of the scapula. There were no overlying skin changes, and there was normal function of the ipsilateral upper extremity. Anteroposterior and lateral chest radiographs revealed no abnormality. Magnetic resonance imaging (MRI) showed an exostosis projecting from the scapular spine measuring 2×6×7 mm with an adjacent cystic mass measuring 5×8×9 mm that was thought to represent bursitis (Figure 1). The decision was made to observe the mass. 

The patient returned to clinic at age 31 months with a new complaint of scant drainage of serous fluid from a pinprick-sized hole located just superolateral to the scapular mass. The child’s mother reported daily manual expression of fluid from the mass via the hole, without which the mass would enlarge. There were no local or systemic signs of infection. A repeat MRI again revealed an exostosis with an adjacent cystic mass with interval enlargement of the cyst (Figure 2). At age 4.5 years, the decision was made to proceed with excision of the osteochondroma and adjacent cystic mass.

The mass was approached via a 2-cm incision designed to excise the tract to the skin. Dissection revealed a sinus tract connecting to a well-defined cystic sac. This sac was attached to the underlying exostosis. The exostosis and attached cyst were excised en bloc. The cyst was opened, revealing foul-smelling, cloudy white fluid that was sent for culture; the specimen was sent for pathology.

The fluid culture grew mixed flora, with no Staphylococcus aureus, group A streptococcus, or Pseudomonas aeruginosa identified. The pathologic examination identified bone with a cartilaginous cap, consistent with osteochondroma (Figure 3), as well as a cyst lined by respiratory epithelium with patchy areas of squamous epithelium and surrounding mucus glands, consistent with bronchogenic cyst (Figure 4). Figure 5 shows the contiguous nature of the 2 lesions.

The postoperative course was uneventful. The patient returned to full use of the left upper extremity and had resolution of all drainage. 

Discussion

Osteochondromas are thought to arise from aberrant growth of the epiphyseal growth plate cartilage. A small portion of the physis herniates past the groove of Ranvier and grows parallel to the normal physis with medullary continuity. This can occur idiopathically or, more rarely, secondary to an identified injury to the growth plate.¹

The formation of bronchogenic cysts is most often attributed to anomalous budding of the ventral foregut during fetal development,⁴ hence the alternative designation of these cysts as foregut cysts. An extrathoracic location of the cyst has been postulated to stem from 2 possible events: a preexisting cyst may migrate out of the thorax prior to closure of the sternal plates, or sternal plate closure may itself pinch off the cyst.^8,9 An alternative explanation is in situ metaplastic development of respiratory epithelium.¹⁰ When located near the skin, these cysts often drain clear fluid.¹¹

Scapular osteochondromas are known to cause various pathologies of the shoulder girdle, including snapping scapula syndrome, chest wall deformity, shoulder impingement, and bursa formation.^12-17 This case, however, is the first known finding of a scapular osteochondroma with a contiguous cutaneous bronchogenic cyst. A putative explanation for their co-occurrence is that local disturbances caused by one lesion stimulated the formation of the second. The direct connection between the bronchogenic cyst and the bone, as has been reported in 3 cases,^7,9,18 seems to favor this explanation. Definitive conclusions regarding any causal relationship are beyond the scope of this single case report.

Definitive management of bronchogenic cysts is complete excision, although the diagnosis is often not made until histopathologic examination has been completed.¹⁹ Osteochondromas are managed with observation unless they are symptomatic.² Malignant degeneration is a rare but documented occurrence in both lesions.^2,20

Conclusion

In approaching the pediatric patient with a cystic mass over the scapula, a cutaneous bronchogenic cyst may be included in the differential diagnosis. This lesion can occur in isolation or can be found with another pathology, such as osteochondroma, as reported here.

Posterior spinal fusion for adolescent idiopathic scoliosis is a relatively common procedure. However, intestinal obstruction is a possible complication in the case of an asthenic adolescent with weight loss after surgery. We present the case of a 12-year-old girl who underwent an uncomplicated posterior spinal fusion with instrumentation for scoliosis and who developed nausea, emesis, and abdominal pain. We also discuss the origins, epidemiology, diagnosis, and treatment of superior mesenteric artery syndrome (SMAS), a rare condition. The patient’s parents provided written informed consent for print and electronic publication of this case report.

Case Report

The patient was a 12-year-old girl with juvenile idiopathic scoliosis. She was seen by a pediatric orthopedist at age 8 after her primary care physician noticed a curve in her back during her physical examination. Given her age and primary curve of 25º, magnetic resonance imaging was ordered, which was negative for syrinx, tethered cord, or bony abnormalities. An underarm thoracolumbosacral orthosis (Boston Brace) was prescribed to be worn 23 hours/day. There was inconsistent follow-up over the next 4 years, and her curve progressed to 55º (right thoracic) and 47º in the lumbar spine (Figures 1, 2). Given the magnitude of the curves, surgical intervention was recommended, because bracing would no longer be beneficial. 

The patient was healthy and appeared vibrant with no medical issues. She weighed 49 kg and her height was 162 cm (body mass index [BMI], 18.6; normal). She underwent segmental posterior spinal instrumentation, and a fusion was performed from T4 to L4 using a cobalt chrome rod. Postoperatively, there were no problems. Her diet was slowly advanced from clear liquids to regular food over 3 days. She was discharged on postoperative day 4. She had no abdominal distention, pain, or nausea. The family was instructed about pain medication (oxycodone liquid, 5 mg every 4 hours as needed) and how to prevent and treat constipation. 

Three days after discharge, her mother called to inquire about positioning because the patient was uncomfortable owing to back pain. There were no abdominal complaints, and she was taking her pain medicine every 4 hours. She was instructed to lie in a comfortable position and to ambulate several times daily. The patient took little food or fluids because of a lack of appetite and back pain. On postoperative day 8, she presented to the emergency department with complaints of generalized abdominal pain and 1 day’s emesis. The patient had not had a bowel movement postoperatively. An acute abdominal series (AAS) was obtained (Figure 3), which noted a nonobstructive bowel gas pattern, with some increased colonic fecal retention. The patient was given intravenous (IV) fluids and an IV anti-emetic, and was admitted for observation. The pediatric surgical team evaluated her and concluded her symptoms resulted from constipation. Her symptoms improved over 2 to 3 days, and she had several bowel movements on day 2 after taking polyethylene glycol, sennosides, and bisacodyl suppositories. At discharge, she was noted to be passing gas, and her abdominal examination revealed no tenderness or guarding. She had mild distention, but it had improved from the previous day. She ate breakfast and ambulated several times. She had no complaints of abdominal pain and was released home with her parents. Staff reiterated instructions regarding constipation, diet, and follow-up. Her discharge weight was 48 kg (down 1 kg) and her BMI was 17.2 (down 1.4; underweight). Her height was now 165 cm (up 3 cm). Postoperative radiographs noted stable fixation with corrected curves (Figures 4, 5).

At home, the patient ate little but continued to drink fluids. On postdischarge day 3, she developed nausea, bilious emesis, and generalized abdominal pain. She returned to the emergency department. At this point, the patient weighed 44.5 kg (down 6.6 kg since the initial surgery) and her BMI was 16.1 (down 2.5; underweight). She was admitted, and IV fluids were initiated. She had more than 1300 mL of bilious emesis. A nasogastric (NG) tube was inserted. Initial laboratory findings were unremarkable other than an increase in serum lipase of 261 U/L. Her amylase level was within normal limits. An AAS was again completed and showed a distended stomach and loop of small bowel below the liver with an air fluid level. There were also distended loops of bowel in the pelvis (Figure 6). 

A pediatric surgical consultant examined her the next morning. An upper gastrointestinal series (UGI) was obtained and showed air fluid levels in the stomach with prompt gastric emptying into a normal caliber duodenal bulb. However, with supine positioning, there was significant dilatation of the second portion of the duodenum with abrupt vertical cutoff just to the right of the spine, compatible with SMAS (Figure 7). There was reflux of contrast material into the stomach from the duodenum, with no passage of barium into the distal duodenum. After the UGI, a nasojejunal (NJ) feeding tube was placed. The tip was left at the beginning of the fourth part of the duodenum. Repeated attempts to pass the NJ feeding tube beyond the fourth part of the duodenum were unsuccessful because of massive gastric distention. The patient was taken to the operating room for placement of a Stamm gastrostomy feeding tube with insertion of a transgastric jejunal (G-J) feeding tube under fluoroscopy (Figure 5). The patient had the G-J feeding tube in place for 6 weeks to augment her enteral nutrition. As she gained weight, her duodenal emptying improved. She gradually transitioned to normal oral intake. She has done well since the G-J feeding tube was removed. 

Discussion

Von Rokitansky first described SMAS in the mid-1800s.¹ The exact pathology was further defined 60 years later when vascular involvement was determined to be the definitive mechanism of obstruction.^2-4 Superior mesenteric artery syndrome is caused by the superior mesenteric vessels compressing the third portion of the duodenum, resulting in an extrinsic obstruction. This syndrome is also commonly called Wilkie disease, after Dr. David Wilkie, who first published in 1927 results of a comprehensive series of 75 patients.¹ The syndrome is also known as arteriomesenteric duodenal compression, aortomesenteric syndrome, chronic duodenal ileus, megaduodenum, and cast syndrome.^1,4,5 The term cast syndrome was derived from events in 1878, when Willet applied a body cast to a scoliosis patient who died after what was termed “fatal vomiting.”³

Epidemiology, Incidence, and Prevalence

While not unheard of, SMAS is an uncommon disorder. There have been only 400 documented reports in the English-language literature since 1980.^5-8 Studies have stated that the incidence of the affected population is less than 0.4%.^5,7,9,10 However, SMAS has been reported to have a mortality rate as high as 33% because of the uncommon nature of the disease and prolonged duration between onset of symptoms and diagnosis.^7,9,11,12 The incidence of SMAS is higher after surgical procedures to correct spinal deformities, with rates between 0.5% and 4.7%.^10,12,13 Females are affected more frequently than males (3:2 ratio).^1,9,14 One large study with 80 patients that spanned 10 years reported that female incidence was 66%, and another study with 75 patients also observed that two-thirds of the patients were women.^1,7 This syndrome commonly affects patients who are tall and thin with an asthenic body habitus.^1,6,11,12 Superior mesenteric artery syndrome develops more commonly in younger patients. Previous studies noted that two-thirds of patients were between ages 10 and 39 years.^1,8 However, given the right set of medical conditions, it can occur in patients of any age.^2,9,15,16 In young, thin patients with scoliosis, the risk of developing SMAS after spinal fusion with instrumentation increases, given their already low weight coupled with the surgical intervention at the height of their longitudinal growth spurt.^1,11,12 

Other patients also at increased risk for developing SMAS include those with anorexia nervosa, psychiatric/emotional disorders, or drug addiction. It can also be found in persons on prolonged bedrest, those who have increased their activity and lost weight volitionally, or patients with illness or injuries, such as burns, trauma, or significant postoperative complications that decrease caloric intake and keep them in a supine position.^2,6,17 The syndrome can be acute or chronic in its presentation.

Anatomy and Physiology

The superior mesenteric artery (SMA) comes off the right anterolateral portion of the abdominal aorta, which is just anterior to the L1 vertebra. It passes over the third part of the duodenum, generally at the L2 level (Figure 8A). The duodenum passes across the aorta at the level of the L3 vertebral body and is suspended between the aorta and the SMA by the ligament of Treitz (Figure 8B).³ The angle between the aorta and SMA (aortomesenteric angle) typically ranges from 25º to 60º with an average of 45º (Figure 8A). The distance between the aorta and SMA at the level of the duodenum is called the aortomesenteric distance, and it normally measures from 10 mm to 28 mm. Obstruction is usually observed at 2 mm to 8 mm (Figure 8C).^1,3

Compression and outlet obstruction from narrowing of the SMA aortomesenteric angle can be caused by a multitude of problems.^3,5,9,17 In chronic conditions, narrowing of the aorto-mesenteric angle could be the result of a shortened ligament, or a low origin of the SMA on the aorta, or a high insertion of the duodenum at the ligament of Treitz. Postoperatively, any change in anatomy caused by adhesions could result in compression as well. Most commonly, however, in those with significant weight loss, such as postoperative spinal fusion patients, there is loss of retroperitoneal fat, which normally acts as a cushion around the duodenum. This allows the SMA to move posteriorly obstructing the duodenum. Lying in a recumbent position along with weight loss also puts patients at risk after surgery.^3,5,9,17 SMAS should be distinguished from other conditions that can cause duodenal obstruction, such as duodenal hematomas and congenital webs. 

Symptoms and Patient Presentation

Whether SMAS is acute or chronic, most patients with SMAS present in a similar fashion. Almost all patients with acute SMAS complain of abdominal pain, nausea, and emesis (usually bilious) that usually occur after eating. Early satiety is commonly observed, resulting from delayed gastric emptying. Abdominal pain may improve when patients lie prone and are in the knee-chest, or lateral decubitus, position. These patients frequently have upper abdominal distention because of massive retention of gastric contents.^4,6,16,18,19 Most spinal fusion patients present with these symptoms 7 to 10 days after surgery.^11-13

Diagnosis

Our first diagnostic tool is a comprehensive history and physical examination. Once that is complete, many radiologic tests can be used to confirm the anatomic abnormality. The first test ordered is a simple AAS, which may show a “double bubble sign” (Figure 6), indicative of duodenal obstruction.⁴ There are several other tests, and each facility and surgeon has a preference as to which is considered the “gold standard.” Upper gastrointestinal (GI) barium studies are the simplest and most reliable. The barium test shows foregut anatomy and, to some extent, function. In SMAS patients, one should see duodenal dilatation and failure of the contrast to flow past the third section of the duodenum, along with an abrupt termination of the barium column as the duodenum crosses the vertebrae. This is the traditional method of diagnosis. There is minimal radiation, and the cost is less than that of many other tests, but it can be uncomfortable for the patient.^1-4

At some institutions, an upper GI barium study is combined with angiography, which can be used to measure aortomesenteric angle and distance.^1,3 Other practitioners prefer computed tomography (CT) with 3-dimensional reconstruction, which allows for measurement of the aortomesenteric angle and distance. In 1 study, CT was found to have an extremely high sensitivity and specificity for these measurements.¹⁰ CT angiography also identifies the obstruction with increased sensitivity, but it is rarely necessary and provides more radiation exposure and increased cost.^1,6,14,19 Abdominal ultrasound has been used to measure the angle of the SMA and the aortomesenteric distance. When combined with endoscopy, this offers an alternative way to diagnose SMAS and decreases radiation exposure. However, it may require sedation or anesthesia.^7,15,17 Overall, 3 criteria are used to define whether a patient has SMAS: duodenal dilatation, an aortomesenteric angle that is less than 25º, and an SMA that is shown to be compressing the third part of the duodenum.⁵

Treatment

Conservative treatment of SMAS usually starts by removing any precipitating factors present, such as a splint or cast that was applied for scoliosis, or ending activity associated with significant weight loss. Medical management consists of IV hydration, anti-emetics, oral feeding restriction, posture therapy, and placement of an NG tube for decompression. In most cases, patients will need to have an NJ feeding tube passed distal to the site of obstruction. This provides access for enteral feeding, and patients will gradually gain weight, repleting their retroperitoneal fat stores, which pushes the SMA forward and relieves the pressure on the duodenum. Electrolyte balance should be closely monitored along with weight gain. A nutritionist is often consulted to prevent underfeeding, which can produce a slow return to weight gain, poor wound healing, and loss of lean body muscle mass; or overfeeding, which can result in hyperglycemia and respiratory failure. Once patients are stable on enteral feedings, they can begin a slow return to oral intake.^2-4,7,12 Total parental nutrition may be needed in some cases, but the risks associated with IV feeding usually outweigh the benefits.⁴ Almost all cases of acute SMAS can be successfully treated medically if diagnosed in a timely manner and supportive treatment begins promptly.⁷

Surgical intervention is rarely necessary for acute SMAS, but when conservative measures fail (after a 4- to 6-week trial), or in the presence of peptic ulcer disease or pancreatitis, this may become an appropriate option. In our patient, multiple attempts at passing an NJ feeding tube were unsuccessful, and she needed an operative procedure for insertion of a G-J feeding tube.  

Further surgical intervention is usually reserved for those patients with long-standing SMAS for whom medical management has failed or other issues, such as pancreatitis, colitis, or megaduodenum, have arisen. Many operations are described in the literature. A duodenojejunostomy to bypass the site of the obstruction is one option. Another is duodenal derotation (Strong procedure) to alter the aortomesenteric angle and place the third and fourth duodenal portions to the right of the SMA. Other procedures include a Roux-en-Y duodenojejunostomy and duodenal uncrossing. A lateral duodenojejunostomy between the second portion of the duodenum and the jejunum is considered the simplest surgical technique. It achieves successful outcomes in 90% of cases.^2-5,14 With regards to SMAS and scoliosis, it is extremely rare that this kind of surgical intervention would be necessary.

Conclusion

When planning operative spinal correction in scoliosis patients (especially females) who have a low BMI at the time of surgery and who have increased thoracic stiffness, be alert for signs and symptoms of SMAS. This rare complication can develop, and timely diagnosis and medical management will decrease morbidity and shorten the length of time needed for nutritional rehabilitation.

Posterior spinal fusion for adolescent idiopathic scoliosis is a relatively common procedure. However, intestinal obstruction is a possible complication in the case of an asthenic adolescent with weight loss after surgery. We present the case of a 12-year-old girl who underwent an uncomplicated posterior spinal fusion with instrumentation for scoliosis and who developed nausea, emesis, and abdominal pain. We also discuss the origins, epidemiology, diagnosis, and treatment of superior mesenteric artery syndrome (SMAS), a rare condition. The patient’s parents provided written informed consent for print and electronic publication of this case report.

Case Report

The patient was a 12-year-old girl with juvenile idiopathic scoliosis. She was seen by a pediatric orthopedist at age 8 after her primary care physician noticed a curve in her back during her physical examination. Given her age and primary curve of 25º, magnetic resonance imaging was ordered, which was negative for syrinx, tethered cord, or bony abnormalities. An underarm thoracolumbosacral orthosis (Boston Brace) was prescribed to be worn 23 hours/day. There was inconsistent follow-up over the next 4 years, and her curve progressed to 55º (right thoracic) and 47º in the lumbar spine (Figures 1, 2). Given the magnitude of the curves, surgical intervention was recommended, because bracing would no longer be beneficial. 

The patient was healthy and appeared vibrant with no medical issues. She weighed 49 kg and her height was 162 cm (body mass index [BMI], 18.6; normal). She underwent segmental posterior spinal instrumentation, and a fusion was performed from T4 to L4 using a cobalt chrome rod. Postoperatively, there were no problems. Her diet was slowly advanced from clear liquids to regular food over 3 days. She was discharged on postoperative day 4. She had no abdominal distention, pain, or nausea. The family was instructed about pain medication (oxycodone liquid, 5 mg every 4 hours as needed) and how to prevent and treat constipation. 

Three days after discharge, her mother called to inquire about positioning because the patient was uncomfortable owing to back pain. There were no abdominal complaints, and she was taking her pain medicine every 4 hours. She was instructed to lie in a comfortable position and to ambulate several times daily. The patient took little food or fluids because of a lack of appetite and back pain. On postoperative day 8, she presented to the emergency department with complaints of generalized abdominal pain and 1 day’s emesis. The patient had not had a bowel movement postoperatively. An acute abdominal series (AAS) was obtained (Figure 3), which noted a nonobstructive bowel gas pattern, with some increased colonic fecal retention. The patient was given intravenous (IV) fluids and an IV anti-emetic, and was admitted for observation. The pediatric surgical team evaluated her and concluded her symptoms resulted from constipation. Her symptoms improved over 2 to 3 days, and she had several bowel movements on day 2 after taking polyethylene glycol, sennosides, and bisacodyl suppositories. At discharge, she was noted to be passing gas, and her abdominal examination revealed no tenderness or guarding. She had mild distention, but it had improved from the previous day. She ate breakfast and ambulated several times. She had no complaints of abdominal pain and was released home with her parents. Staff reiterated instructions regarding constipation, diet, and follow-up. Her discharge weight was 48 kg (down 1 kg) and her BMI was 17.2 (down 1.4; underweight). Her height was now 165 cm (up 3 cm). Postoperative radiographs noted stable fixation with corrected curves (Figures 4, 5).

At home, the patient ate little but continued to drink fluids. On postdischarge day 3, she developed nausea, bilious emesis, and generalized abdominal pain. She returned to the emergency department. At this point, the patient weighed 44.5 kg (down 6.6 kg since the initial surgery) and her BMI was 16.1 (down 2.5; underweight). She was admitted, and IV fluids were initiated. She had more than 1300 mL of bilious emesis. A nasogastric (NG) tube was inserted. Initial laboratory findings were unremarkable other than an increase in serum lipase of 261 U/L. Her amylase level was within normal limits. An AAS was again completed and showed a distended stomach and loop of small bowel below the liver with an air fluid level. There were also distended loops of bowel in the pelvis (Figure 6). 

A pediatric surgical consultant examined her the next morning. An upper gastrointestinal series (UGI) was obtained and showed air fluid levels in the stomach with prompt gastric emptying into a normal caliber duodenal bulb. However, with supine positioning, there was significant dilatation of the second portion of the duodenum with abrupt vertical cutoff just to the right of the spine, compatible with SMAS (Figure 7). There was reflux of contrast material into the stomach from the duodenum, with no passage of barium into the distal duodenum. After the UGI, a nasojejunal (NJ) feeding tube was placed. The tip was left at the beginning of the fourth part of the duodenum. Repeated attempts to pass the NJ feeding tube beyond the fourth part of the duodenum were unsuccessful because of massive gastric distention. The patient was taken to the operating room for placement of a Stamm gastrostomy feeding tube with insertion of a transgastric jejunal (G-J) feeding tube under fluoroscopy (Figure 5). The patient had the G-J feeding tube in place for 6 weeks to augment her enteral nutrition. As she gained weight, her duodenal emptying improved. She gradually transitioned to normal oral intake. She has done well since the G-J feeding tube was removed. 

Discussion

Von Rokitansky first described SMAS in the mid-1800s.¹ The exact pathology was further defined 60 years later when vascular involvement was determined to be the definitive mechanism of obstruction.^2-4 Superior mesenteric artery syndrome is caused by the superior mesenteric vessels compressing the third portion of the duodenum, resulting in an extrinsic obstruction. This syndrome is also commonly called Wilkie disease, after Dr. David Wilkie, who first published in 1927 results of a comprehensive series of 75 patients.¹ The syndrome is also known as arteriomesenteric duodenal compression, aortomesenteric syndrome, chronic duodenal ileus, megaduodenum, and cast syndrome.^1,4,5 The term cast syndrome was derived from events in 1878, when Willet applied a body cast to a scoliosis patient who died after what was termed “fatal vomiting.”³

Epidemiology, Incidence, and Prevalence

While not unheard of, SMAS is an uncommon disorder. There have been only 400 documented reports in the English-language literature since 1980.^5-8 Studies have stated that the incidence of the affected population is less than 0.4%.^5,7,9,10 However, SMAS has been reported to have a mortality rate as high as 33% because of the uncommon nature of the disease and prolonged duration between onset of symptoms and diagnosis.^7,9,11,12 The incidence of SMAS is higher after surgical procedures to correct spinal deformities, with rates between 0.5% and 4.7%.^10,12,13 Females are affected more frequently than males (3:2 ratio).^1,9,14 One large study with 80 patients that spanned 10 years reported that female incidence was 66%, and another study with 75 patients also observed that two-thirds of the patients were women.^1,7 This syndrome commonly affects patients who are tall and thin with an asthenic body habitus.^1,6,11,12 Superior mesenteric artery syndrome develops more commonly in younger patients. Previous studies noted that two-thirds of patients were between ages 10 and 39 years.^1,8 However, given the right set of medical conditions, it can occur in patients of any age.^2,9,15,16 In young, thin patients with scoliosis, the risk of developing SMAS after spinal fusion with instrumentation increases, given their already low weight coupled with the surgical intervention at the height of their longitudinal growth spurt.^1,11,12 

Other patients also at increased risk for developing SMAS include those with anorexia nervosa, psychiatric/emotional disorders, or drug addiction. It can also be found in persons on prolonged bedrest, those who have increased their activity and lost weight volitionally, or patients with illness or injuries, such as burns, trauma, or significant postoperative complications that decrease caloric intake and keep them in a supine position.^2,6,17 The syndrome can be acute or chronic in its presentation.

Anatomy and Physiology

The superior mesenteric artery (SMA) comes off the right anterolateral portion of the abdominal aorta, which is just anterior to the L1 vertebra. It passes over the third part of the duodenum, generally at the L2 level (Figure 8A). The duodenum passes across the aorta at the level of the L3 vertebral body and is suspended between the aorta and the SMA by the ligament of Treitz (Figure 8B).³ The angle between the aorta and SMA (aortomesenteric angle) typically ranges from 25º to 60º with an average of 45º (Figure 8A). The distance between the aorta and SMA at the level of the duodenum is called the aortomesenteric distance, and it normally measures from 10 mm to 28 mm. Obstruction is usually observed at 2 mm to 8 mm (Figure 8C).^1,3

Compression and outlet obstruction from narrowing of the SMA aortomesenteric angle can be caused by a multitude of problems.^3,5,9,17 In chronic conditions, narrowing of the aorto-mesenteric angle could be the result of a shortened ligament, or a low origin of the SMA on the aorta, or a high insertion of the duodenum at the ligament of Treitz. Postoperatively, any change in anatomy caused by adhesions could result in compression as well. Most commonly, however, in those with significant weight loss, such as postoperative spinal fusion patients, there is loss of retroperitoneal fat, which normally acts as a cushion around the duodenum. This allows the SMA to move posteriorly obstructing the duodenum. Lying in a recumbent position along with weight loss also puts patients at risk after surgery.^3,5,9,17 SMAS should be distinguished from other conditions that can cause duodenal obstruction, such as duodenal hematomas and congenital webs. 

Symptoms and Patient Presentation

Whether SMAS is acute or chronic, most patients with SMAS present in a similar fashion. Almost all patients with acute SMAS complain of abdominal pain, nausea, and emesis (usually bilious) that usually occur after eating. Early satiety is commonly observed, resulting from delayed gastric emptying. Abdominal pain may improve when patients lie prone and are in the knee-chest, or lateral decubitus, position. These patients frequently have upper abdominal distention because of massive retention of gastric contents.^4,6,16,18,19 Most spinal fusion patients present with these symptoms 7 to 10 days after surgery.^11-13

Diagnosis

Our first diagnostic tool is a comprehensive history and physical examination. Once that is complete, many radiologic tests can be used to confirm the anatomic abnormality. The first test ordered is a simple AAS, which may show a “double bubble sign” (Figure 6), indicative of duodenal obstruction.⁴ There are several other tests, and each facility and surgeon has a preference as to which is considered the “gold standard.” Upper gastrointestinal (GI) barium studies are the simplest and most reliable. The barium test shows foregut anatomy and, to some extent, function. In SMAS patients, one should see duodenal dilatation and failure of the contrast to flow past the third section of the duodenum, along with an abrupt termination of the barium column as the duodenum crosses the vertebrae. This is the traditional method of diagnosis. There is minimal radiation, and the cost is less than that of many other tests, but it can be uncomfortable for the patient.^1-4

At some institutions, an upper GI barium study is combined with angiography, which can be used to measure aortomesenteric angle and distance.^1,3 Other practitioners prefer computed tomography (CT) with 3-dimensional reconstruction, which allows for measurement of the aortomesenteric angle and distance. In 1 study, CT was found to have an extremely high sensitivity and specificity for these measurements.¹⁰ CT angiography also identifies the obstruction with increased sensitivity, but it is rarely necessary and provides more radiation exposure and increased cost.^1,6,14,19 Abdominal ultrasound has been used to measure the angle of the SMA and the aortomesenteric distance. When combined with endoscopy, this offers an alternative way to diagnose SMAS and decreases radiation exposure. However, it may require sedation or anesthesia.^7,15,17 Overall, 3 criteria are used to define whether a patient has SMAS: duodenal dilatation, an aortomesenteric angle that is less than 25º, and an SMA that is shown to be compressing the third part of the duodenum.⁵

Treatment

Conservative treatment of SMAS usually starts by removing any precipitating factors present, such as a splint or cast that was applied for scoliosis, or ending activity associated with significant weight loss. Medical management consists of IV hydration, anti-emetics, oral feeding restriction, posture therapy, and placement of an NG tube for decompression. In most cases, patients will need to have an NJ feeding tube passed distal to the site of obstruction. This provides access for enteral feeding, and patients will gradually gain weight, repleting their retroperitoneal fat stores, which pushes the SMA forward and relieves the pressure on the duodenum. Electrolyte balance should be closely monitored along with weight gain. A nutritionist is often consulted to prevent underfeeding, which can produce a slow return to weight gain, poor wound healing, and loss of lean body muscle mass; or overfeeding, which can result in hyperglycemia and respiratory failure. Once patients are stable on enteral feedings, they can begin a slow return to oral intake.^2-4,7,12 Total parental nutrition may be needed in some cases, but the risks associated with IV feeding usually outweigh the benefits.⁴ Almost all cases of acute SMAS can be successfully treated medically if diagnosed in a timely manner and supportive treatment begins promptly.⁷

Surgical intervention is rarely necessary for acute SMAS, but when conservative measures fail (after a 4- to 6-week trial), or in the presence of peptic ulcer disease or pancreatitis, this may become an appropriate option. In our patient, multiple attempts at passing an NJ feeding tube were unsuccessful, and she needed an operative procedure for insertion of a G-J feeding tube.  

Further surgical intervention is usually reserved for those patients with long-standing SMAS for whom medical management has failed or other issues, such as pancreatitis, colitis, or megaduodenum, have arisen. Many operations are described in the literature. A duodenojejunostomy to bypass the site of the obstruction is one option. Another is duodenal derotation (Strong procedure) to alter the aortomesenteric angle and place the third and fourth duodenal portions to the right of the SMA. Other procedures include a Roux-en-Y duodenojejunostomy and duodenal uncrossing. A lateral duodenojejunostomy between the second portion of the duodenum and the jejunum is considered the simplest surgical technique. It achieves successful outcomes in 90% of cases.^2-5,14 With regards to SMAS and scoliosis, it is extremely rare that this kind of surgical intervention would be necessary.

Conclusion

When planning operative spinal correction in scoliosis patients (especially females) who have a low BMI at the time of surgery and who have increased thoracic stiffness, be alert for signs and symptoms of SMAS. This rare complication can develop, and timely diagnosis and medical management will decrease morbidity and shorten the length of time needed for nutritional rehabilitation.

Posterior spinal fusion for adolescent idiopathic scoliosis is a relatively common procedure. However, intestinal obstruction is a possible complication in the case of an asthenic adolescent with weight loss after surgery. We present the case of a 12-year-old girl who underwent an uncomplicated posterior spinal fusion with instrumentation for scoliosis and who developed nausea, emesis, and abdominal pain. We also discuss the origins, epidemiology, diagnosis, and treatment of superior mesenteric artery syndrome (SMAS), a rare condition. The patient’s parents provided written informed consent for print and electronic publication of this case report.

Case Report

The patient was a 12-year-old girl with juvenile idiopathic scoliosis. She was seen by a pediatric orthopedist at age 8 after her primary care physician noticed a curve in her back during her physical examination. Given her age and primary curve of 25º, magnetic resonance imaging was ordered, which was negative for syrinx, tethered cord, or bony abnormalities. An underarm thoracolumbosacral orthosis (Boston Brace) was prescribed to be worn 23 hours/day. There was inconsistent follow-up over the next 4 years, and her curve progressed to 55º (right thoracic) and 47º in the lumbar spine (Figures 1, 2). Given the magnitude of the curves, surgical intervention was recommended, because bracing would no longer be beneficial. 

The patient was healthy and appeared vibrant with no medical issues. She weighed 49 kg and her height was 162 cm (body mass index [BMI], 18.6; normal). She underwent segmental posterior spinal instrumentation, and a fusion was performed from T4 to L4 using a cobalt chrome rod. Postoperatively, there were no problems. Her diet was slowly advanced from clear liquids to regular food over 3 days. She was discharged on postoperative day 4. She had no abdominal distention, pain, or nausea. The family was instructed about pain medication (oxycodone liquid, 5 mg every 4 hours as needed) and how to prevent and treat constipation. 

Three days after discharge, her mother called to inquire about positioning because the patient was uncomfortable owing to back pain. There were no abdominal complaints, and she was taking her pain medicine every 4 hours. She was instructed to lie in a comfortable position and to ambulate several times daily. The patient took little food or fluids because of a lack of appetite and back pain. On postoperative day 8, she presented to the emergency department with complaints of generalized abdominal pain and 1 day’s emesis. The patient had not had a bowel movement postoperatively. An acute abdominal series (AAS) was obtained (Figure 3), which noted a nonobstructive bowel gas pattern, with some increased colonic fecal retention. The patient was given intravenous (IV) fluids and an IV anti-emetic, and was admitted for observation. The pediatric surgical team evaluated her and concluded her symptoms resulted from constipation. Her symptoms improved over 2 to 3 days, and she had several bowel movements on day 2 after taking polyethylene glycol, sennosides, and bisacodyl suppositories. At discharge, she was noted to be passing gas, and her abdominal examination revealed no tenderness or guarding. She had mild distention, but it had improved from the previous day. She ate breakfast and ambulated several times. She had no complaints of abdominal pain and was released home with her parents. Staff reiterated instructions regarding constipation, diet, and follow-up. Her discharge weight was 48 kg (down 1 kg) and her BMI was 17.2 (down 1.4; underweight). Her height was now 165 cm (up 3 cm). Postoperative radiographs noted stable fixation with corrected curves (Figures 4, 5).

At home, the patient ate little but continued to drink fluids. On postdischarge day 3, she developed nausea, bilious emesis, and generalized abdominal pain. She returned to the emergency department. At this point, the patient weighed 44.5 kg (down 6.6 kg since the initial surgery) and her BMI was 16.1 (down 2.5; underweight). She was admitted, and IV fluids were initiated. She had more than 1300 mL of bilious emesis. A nasogastric (NG) tube was inserted. Initial laboratory findings were unremarkable other than an increase in serum lipase of 261 U/L. Her amylase level was within normal limits. An AAS was again completed and showed a distended stomach and loop of small bowel below the liver with an air fluid level. There were also distended loops of bowel in the pelvis (Figure 6). 

A pediatric surgical consultant examined her the next morning. An upper gastrointestinal series (UGI) was obtained and showed air fluid levels in the stomach with prompt gastric emptying into a normal caliber duodenal bulb. However, with supine positioning, there was significant dilatation of the second portion of the duodenum with abrupt vertical cutoff just to the right of the spine, compatible with SMAS (Figure 7). There was reflux of contrast material into the stomach from the duodenum, with no passage of barium into the distal duodenum. After the UGI, a nasojejunal (NJ) feeding tube was placed. The tip was left at the beginning of the fourth part of the duodenum. Repeated attempts to pass the NJ feeding tube beyond the fourth part of the duodenum were unsuccessful because of massive gastric distention. The patient was taken to the operating room for placement of a Stamm gastrostomy feeding tube with insertion of a transgastric jejunal (G-J) feeding tube under fluoroscopy (Figure 5). The patient had the G-J feeding tube in place for 6 weeks to augment her enteral nutrition. As she gained weight, her duodenal emptying improved. She gradually transitioned to normal oral intake. She has done well since the G-J feeding tube was removed. 

Discussion

Von Rokitansky first described SMAS in the mid-1800s.¹ The exact pathology was further defined 60 years later when vascular involvement was determined to be the definitive mechanism of obstruction.^2-4 Superior mesenteric artery syndrome is caused by the superior mesenteric vessels compressing the third portion of the duodenum, resulting in an extrinsic obstruction. This syndrome is also commonly called Wilkie disease, after Dr. David Wilkie, who first published in 1927 results of a comprehensive series of 75 patients.¹ The syndrome is also known as arteriomesenteric duodenal compression, aortomesenteric syndrome, chronic duodenal ileus, megaduodenum, and cast syndrome.^1,4,5 The term cast syndrome was derived from events in 1878, when Willet applied a body cast to a scoliosis patient who died after what was termed “fatal vomiting.”³

Epidemiology, Incidence, and Prevalence

While not unheard of, SMAS is an uncommon disorder. There have been only 400 documented reports in the English-language literature since 1980.^5-8 Studies have stated that the incidence of the affected population is less than 0.4%.^5,7,9,10 However, SMAS has been reported to have a mortality rate as high as 33% because of the uncommon nature of the disease and prolonged duration between onset of symptoms and diagnosis.^7,9,11,12 The incidence of SMAS is higher after surgical procedures to correct spinal deformities, with rates between 0.5% and 4.7%.^10,12,13 Females are affected more frequently than males (3:2 ratio).^1,9,14 One large study with 80 patients that spanned 10 years reported that female incidence was 66%, and another study with 75 patients also observed that two-thirds of the patients were women.^1,7 This syndrome commonly affects patients who are tall and thin with an asthenic body habitus.^1,6,11,12 Superior mesenteric artery syndrome develops more commonly in younger patients. Previous studies noted that two-thirds of patients were between ages 10 and 39 years.^1,8 However, given the right set of medical conditions, it can occur in patients of any age.^2,9,15,16 In young, thin patients with scoliosis, the risk of developing SMAS after spinal fusion with instrumentation increases, given their already low weight coupled with the surgical intervention at the height of their longitudinal growth spurt.^1,11,12 

Other patients also at increased risk for developing SMAS include those with anorexia nervosa, psychiatric/emotional disorders, or drug addiction. It can also be found in persons on prolonged bedrest, those who have increased their activity and lost weight volitionally, or patients with illness or injuries, such as burns, trauma, or significant postoperative complications that decrease caloric intake and keep them in a supine position.^2,6,17 The syndrome can be acute or chronic in its presentation.

Anatomy and Physiology

The superior mesenteric artery (SMA) comes off the right anterolateral portion of the abdominal aorta, which is just anterior to the L1 vertebra. It passes over the third part of the duodenum, generally at the L2 level (Figure 8A). The duodenum passes across the aorta at the level of the L3 vertebral body and is suspended between the aorta and the SMA by the ligament of Treitz (Figure 8B).³ The angle between the aorta and SMA (aortomesenteric angle) typically ranges from 25º to 60º with an average of 45º (Figure 8A). The distance between the aorta and SMA at the level of the duodenum is called the aortomesenteric distance, and it normally measures from 10 mm to 28 mm. Obstruction is usually observed at 2 mm to 8 mm (Figure 8C).^1,3

Compression and outlet obstruction from narrowing of the SMA aortomesenteric angle can be caused by a multitude of problems.^3,5,9,17 In chronic conditions, narrowing of the aorto-mesenteric angle could be the result of a shortened ligament, or a low origin of the SMA on the aorta, or a high insertion of the duodenum at the ligament of Treitz. Postoperatively, any change in anatomy caused by adhesions could result in compression as well. Most commonly, however, in those with significant weight loss, such as postoperative spinal fusion patients, there is loss of retroperitoneal fat, which normally acts as a cushion around the duodenum. This allows the SMA to move posteriorly obstructing the duodenum. Lying in a recumbent position along with weight loss also puts patients at risk after surgery.^3,5,9,17 SMAS should be distinguished from other conditions that can cause duodenal obstruction, such as duodenal hematomas and congenital webs. 

Symptoms and Patient Presentation

Whether SMAS is acute or chronic, most patients with SMAS present in a similar fashion. Almost all patients with acute SMAS complain of abdominal pain, nausea, and emesis (usually bilious) that usually occur after eating. Early satiety is commonly observed, resulting from delayed gastric emptying. Abdominal pain may improve when patients lie prone and are in the knee-chest, or lateral decubitus, position. These patients frequently have upper abdominal distention because of massive retention of gastric contents.^4,6,16,18,19 Most spinal fusion patients present with these symptoms 7 to 10 days after surgery.^11-13

Diagnosis

Our first diagnostic tool is a comprehensive history and physical examination. Once that is complete, many radiologic tests can be used to confirm the anatomic abnormality. The first test ordered is a simple AAS, which may show a “double bubble sign” (Figure 6), indicative of duodenal obstruction.⁴ There are several other tests, and each facility and surgeon has a preference as to which is considered the “gold standard.” Upper gastrointestinal (GI) barium studies are the simplest and most reliable. The barium test shows foregut anatomy and, to some extent, function. In SMAS patients, one should see duodenal dilatation and failure of the contrast to flow past the third section of the duodenum, along with an abrupt termination of the barium column as the duodenum crosses the vertebrae. This is the traditional method of diagnosis. There is minimal radiation, and the cost is less than that of many other tests, but it can be uncomfortable for the patient.^1-4

At some institutions, an upper GI barium study is combined with angiography, which can be used to measure aortomesenteric angle and distance.^1,3 Other practitioners prefer computed tomography (CT) with 3-dimensional reconstruction, which allows for measurement of the aortomesenteric angle and distance. In 1 study, CT was found to have an extremely high sensitivity and specificity for these measurements.¹⁰ CT angiography also identifies the obstruction with increased sensitivity, but it is rarely necessary and provides more radiation exposure and increased cost.^1,6,14,19 Abdominal ultrasound has been used to measure the angle of the SMA and the aortomesenteric distance. When combined with endoscopy, this offers an alternative way to diagnose SMAS and decreases radiation exposure. However, it may require sedation or anesthesia.^7,15,17 Overall, 3 criteria are used to define whether a patient has SMAS: duodenal dilatation, an aortomesenteric angle that is less than 25º, and an SMA that is shown to be compressing the third part of the duodenum.⁵

Treatment

Conservative treatment of SMAS usually starts by removing any precipitating factors present, such as a splint or cast that was applied for scoliosis, or ending activity associated with significant weight loss. Medical management consists of IV hydration, anti-emetics, oral feeding restriction, posture therapy, and placement of an NG tube for decompression. In most cases, patients will need to have an NJ feeding tube passed distal to the site of obstruction. This provides access for enteral feeding, and patients will gradually gain weight, repleting their retroperitoneal fat stores, which pushes the SMA forward and relieves the pressure on the duodenum. Electrolyte balance should be closely monitored along with weight gain. A nutritionist is often consulted to prevent underfeeding, which can produce a slow return to weight gain, poor wound healing, and loss of lean body muscle mass; or overfeeding, which can result in hyperglycemia and respiratory failure. Once patients are stable on enteral feedings, they can begin a slow return to oral intake.^2-4,7,12 Total parental nutrition may be needed in some cases, but the risks associated with IV feeding usually outweigh the benefits.⁴ Almost all cases of acute SMAS can be successfully treated medically if diagnosed in a timely manner and supportive treatment begins promptly.⁷

Surgical intervention is rarely necessary for acute SMAS, but when conservative measures fail (after a 4- to 6-week trial), or in the presence of peptic ulcer disease or pancreatitis, this may become an appropriate option. In our patient, multiple attempts at passing an NJ feeding tube were unsuccessful, and she needed an operative procedure for insertion of a G-J feeding tube.  

Further surgical intervention is usually reserved for those patients with long-standing SMAS for whom medical management has failed or other issues, such as pancreatitis, colitis, or megaduodenum, have arisen. Many operations are described in the literature. A duodenojejunostomy to bypass the site of the obstruction is one option. Another is duodenal derotation (Strong procedure) to alter the aortomesenteric angle and place the third and fourth duodenal portions to the right of the SMA. Other procedures include a Roux-en-Y duodenojejunostomy and duodenal uncrossing. A lateral duodenojejunostomy between the second portion of the duodenum and the jejunum is considered the simplest surgical technique. It achieves successful outcomes in 90% of cases.^2-5,14 With regards to SMAS and scoliosis, it is extremely rare that this kind of surgical intervention would be necessary.

Conclusion

When planning operative spinal correction in scoliosis patients (especially females) who have a low BMI at the time of surgery and who have increased thoracic stiffness, be alert for signs and symptoms of SMAS. This rare complication can develop, and timely diagnosis and medical management will decrease morbidity and shorten the length of time needed for nutritional rehabilitation.

Ollier disease, or multiple enchondromatosis, is a rare nonfamilial condition characterized by multiple cartilaginous tumors often beginning in early childhood. There is significant variation in disease distribution, location, size, number of lesions, and behavior, but the tumors are often located unilaterally.¹ Enchondromas are most commonly found in the metacarpals, metatarsals, and phalanges, and develop from metaphyseal bone in close proximity to the physis. They frequently present as painless masses or are incidentally noted during the evaluation of another musculoskeletal condition. Radiographically, enchondromas of the hands and feet appear as oval radiolucencies with thinned, sclerotic rims. The lesions have varying degrees of mineralization and endosteal scalloping, and may expand the bone.² Enchondromas usually enlarge until skeletal maturity and have been observed to ossify spontaneously.^1,3 The clinical course of Ollier disease is variable, and a number of cases of significant hand deformity and malignant transformation have been reported.^4-6

In this case report, we present a mild form of Ollier disease isolated to the patient’s left hand, which we followed for 8 years, demonstrating part of the natural history of these lesions. We discuss the patient’s clinical features, radiologic findings, diagnosis, treatment, prognosis, and follow-up, as well as review the literature. The patient and the patient’s family provided written informed consent for print and electronic publication of this case report.

Case Report

A 10-year-old, right-handed girl was referred to our department for the evaluation of left-hand masses. At age 3 years, the patient underwent a chondroma excision from the middle phalanx of her middle finger on her left hand. No operative or pathology report was available from this surgery, and the patient tolerated the procedure well without any complications. At the time of presentation, the masses did not cause any pain, motor or sensory dysfunction, or any systemic symptoms. No history of recent or distant trauma was elicited. The patient’s medical and family history was unremarkable.

On physical examination, there was a firm, immobile, nontender palpable mass over the dorsal aspect of the distal second metacarpal bone of the left hand. The mass extended medially between the second and third metacarpals. A second small, firm, nontender left-hand mass was palpated over the volar aspect of her proximal phalanx on her index finger. She was neurovascularly intact with full active range of motion of the metacarpophalangeal and proximal and distal interphalangeal joints. There was no angular deformity of the digits. Plain radiographs taken at the time of initial presentation showed a 2.3×1.7-cm radiolucent lesion located in the metaphysis and diaphysis of the second metacarpal of the left hand (Figures 1A-1C). The lesion had varying degrees of mineralization with cortical thinning and expansion in the volar, dorsal, radial, and ulnar directions, consistent with a chondroid lesion. The second and third lesions were oval radiolucencies with sclerotic rims located at the metaphyseal-diaphyseal junction of the proximal phalanx of the index finger and middle phalanx of the middle finger, respectively. No fractures were identified in the radiographs, and the physes were open at this time. The patient was diagnosed with multiple enchondromatosis, or Ollier disease.

Our case showed 1 episode of pain and tenderness to palpation at the second proximal phalanx approximately 6 months after initial presentation. We attributed the pain and tenderness to a small pathologic fracture but did not see radiographic evidence of this. We elected to provide a trial of supportive measures, such as splinting and buddy taping, and to monitor the pain with a tentative plan of open biopsy with curettage and bone grafting if the pain persisted or evidence of fracture was seen on radiographs. The pain and tenderness to palpation resolved at a follow-up visit, and the surgery was deferred.

The patient was treated nonoperatively at initial presentation given the lack of significant cosmetic deformity or functional compromise and was advised close follow-up at 3 and 6 months. Given the absence of disease progression, annual checks (ie, clinical examination and radiographs) in a skeletally immature patient were decided on after consultation with the patient and parent. The family was educated about the possibility of pathologic fracture from minimal trauma to the hand versus the small risk of iatrogenic physeal injury with surgical curettage and bone grafting. No protective splinting was offered. A favorable prognosis and reassurance was provided to the patient and family, given the absence of symptoms, low suspicion and risk of malignant transformation, and stability of the lesion. Serial radiographs showed gradual increases in the lesions’ sizes but were consistent with the stable growth of the metacarpal and phalanges. With the patient nearing skeletal maturity, no pathologic fractures were identified on radiography during follow-up, and the risks of surgery lessened with growth; however, the continued absence of symptoms led to the mutual decision to continue observation.

Nearly 8 years after initial presentation, plain radiographs showed closed physes and partially ossified bone masses (Figures 2A-2C). The metacarpal lesion measured 3.2×1.5 cm, and the cortex appeared thickened and regular. The proximal phalanx lesion had a thickened cortex without periosteal reaction, and the middle phalanx lesion appeared to be completely healed. The patient has been asymptomatic for many years, and she has retained complete function of her left hand without any growth retardation, angular deformity, or pathologic fracture. A small but potential risk of malignant transformation was discussed with the patient and her family, as was the need for lifetime follow-up. We intend to follow the enchondromas clinically and radiographically every 2 years and obtain new radiographs if the mass presents with new clinical findings, such as enlargement or pain, for surveillance of tumor transformation. If the patient desired or symptoms developed, curettage and bone grafting would be offered, and the surgical tissue would be sent for pathologic analysis. A bone scan that was obtained at the request of the patient, when she was 21 years old, showed no other sites of disease besides the fingers.

Discussion

Multiple enchondromatosis was first described by Ollier at the turn of the 19th century and has been estimated to affect one in every 100,000 persons.¹ The low prevalence and variable manifestations of Ollier disease lead clinicians to handle the disease and its complications, namely skeletal deformity and malignant transformation, on a case-by-case approach. Additionally, the prognosis of Ollier disease with malignant transformation is quite variable, with studies reporting the estimated incidence as 5% to 50%.⁷ Muramatsu and colleagues⁶ reported that the occurrence of malignant transformation of multiple enchondromas limited to the bones of the hand was extremely rare, with only 12 cases of malignant transformation. Enchondromas of the pelvis, scapula, and long bones of the extremities have increased risks and rates of secondary transformation to chondrosarcoma.⁸

A recent large European multicenter retrospective study investigating the clinical characteristics and behavior of enchondromas in 144 patients with Ollier disease has provided new information regarding this rare disease.⁷ Verdegaal and colleagues⁷ divided patients into 3 categories depending on their distribution of enchondromas. The development of chondrosarcoma was notably different between individuals with enchondromas limited to the small bones of the hands and feet (15%, group I) versus individuals with enchondromas limited to the long bones and flat bones (43%, group II) or individuals with enchondromas of the short, long, and flat bones (46%, group III).⁷ The only location found to be statistically significant for the development of chondrosarcoma was the pelvis.

The clinical findings associated with risk of malignant transformation of enchondromas are increasing size of the lesion and onset of pain and tenderness. Dahlin and Salvador⁹ reported that only 60% of patients with chondrosarcoma of the hand experience pain. The absence of pain may lead to a delay in patient presentation to the clinician.^5,6 Radiographic findings of malignant transformation include the classic features of temporal increases in the lesion’s size after skeletal maturity and cortical destruction associated with soft-tissue invasion. However, both findings are nonspecific for differentiating enchondromas from grade 1 chondrosarcomas as described by Geirnaerdt and colleagues.¹⁰

Sassoon and colleagues¹¹ reported on a series of hand enchondromas treated operatively. Subgroup analysis between pathologic fractures treated primarily or in delayed fashion showed similar outcomes for achieving full motion and similar number of complications; however, they noted that the delayed group required 7 more weeks of immobilization. Additionally, review of the whole series showed 1 episode of metacarpal shortening and 1 occurrence of angular malalignment. In our patient, we were concerned about introducing an iatrogenic cosmetic deformity, and we believed a pathologic fracture could be managed expectantly. Overall, patients without pathologic fracture treated surgically experienced a complication rate of 12%, whereas patients with a fracture had a complication rate of 20%.¹¹ The majority of patients with multiple enchondromatosis treated with surgical curettage and grafting had successful outcomes, with 86% of patients regaining full motion, but the recurrence rate was 21%.¹¹ Patients with expansile lesions regained less motion than patients with nonexpansile lesions. There was a single lesion believed preoperatively to be an enchondroma, but it underwent malignant transformation, as confirmed on intraoperative pathology. This patient had Maffucci syndrome and was treated with an amputation through the metacarpophalangeal joint.

There are 3 options for treating hand enchondromas: observation, curettage alone, or curettage with bone grafting. There is no consensus about conservative management, timing of intervention, or risk of pathologic fracture. Each patient is treated individually with attention to reason for presentation, number of lesions, associated pain, deformity, or pathologic fracture. Operative criteria include high risk of pathologic fracture based on location of enchondroma, cortical thinning, and previous pathologic fracture with resulting angular deformity. Nonoperative management may increase the risk of pathologic fracture, particularly in patients involved in aggressive contact sports, but the physician may offer protective splinting or counsel the patient on activity modification. Our case provides a study of the natural history of multiple enchondromatosis and shows mild increases in the lesions’ sizes during the 8-year follow-up. This was an expected finding given the patient’s immature skeleton. The lesions’ cortices continued to ossify after the physes closed and now provides an excellent comparison for the identification of future malignant changes. 

Histologic analysis of biopsied or surgically treated lesions contributes to the differentiation between benign hand enchondromas and chondrosarcoma. Pathologic findings must be correlated with clinical and radiographic findings because hand enchondromas contain cytologic features of chondrosarcoma.¹² In a series of 55 patients with chondrosarcoma, Liu and colleagues⁸ reported no cases from the hand. Verdegaal and colleagues⁷ reported a total of 13 chondrosarcomas in the metacarpals and hand phalanges in 97 group I and III patients. Five of these lesions were grade 1, 2 were grade 2, 1 was grade 3, and 5 lesions were unknown.

For patients with multiple enchondromatosis limited to the hands, prognosis is relatively good with respect to risk of secondary chondrosarcoma transformation, metastasis of secondary chondrosarcoma, and death. Verdegaal and colleagues⁷ reported the rate of secondary transformation in the hand to be 15%. Patil and colleagues¹³ reported no distant metastases in 23 patients with hand chondrosarcoma at mean follow-up of 8.5 years (range, 2-19 years), although none of their patients had Ollier disease. Verdegaal and colleagues⁷ reported 7 of the 8 deaths in their study were related to development of pulmonary metastases; however, none originated from chondrosarcomas in the hand. Additionally, there were no disease-related deaths in 29 group I patients. Herget and colleagues,¹⁴ in summarizing the literature, postulated that the overall survival rate of patients with secondary chondrosarcoma at 5 years is approximately 90%.

In our case, the patient, who had 3 enchondromas isolated to the left hand, can be categorized in group I. Thus, this case highlights the natural history of a patient with hand enchondromas and demonstrates that enchondromatosis of the short tubular bones of the hands can mature and ossify.

Ollier disease, or multiple enchondromatosis, is a rare nonfamilial condition characterized by multiple cartilaginous tumors often beginning in early childhood. There is significant variation in disease distribution, location, size, number of lesions, and behavior, but the tumors are often located unilaterally.¹ Enchondromas are most commonly found in the metacarpals, metatarsals, and phalanges, and develop from metaphyseal bone in close proximity to the physis. They frequently present as painless masses or are incidentally noted during the evaluation of another musculoskeletal condition. Radiographically, enchondromas of the hands and feet appear as oval radiolucencies with thinned, sclerotic rims. The lesions have varying degrees of mineralization and endosteal scalloping, and may expand the bone.² Enchondromas usually enlarge until skeletal maturity and have been observed to ossify spontaneously.^1,3 The clinical course of Ollier disease is variable, and a number of cases of significant hand deformity and malignant transformation have been reported.^4-6

In this case report, we present a mild form of Ollier disease isolated to the patient’s left hand, which we followed for 8 years, demonstrating part of the natural history of these lesions. We discuss the patient’s clinical features, radiologic findings, diagnosis, treatment, prognosis, and follow-up, as well as review the literature. The patient and the patient’s family provided written informed consent for print and electronic publication of this case report.

Case Report

A 10-year-old, right-handed girl was referred to our department for the evaluation of left-hand masses. At age 3 years, the patient underwent a chondroma excision from the middle phalanx of her middle finger on her left hand. No operative or pathology report was available from this surgery, and the patient tolerated the procedure well without any complications. At the time of presentation, the masses did not cause any pain, motor or sensory dysfunction, or any systemic symptoms. No history of recent or distant trauma was elicited. The patient’s medical and family history was unremarkable.

On physical examination, there was a firm, immobile, nontender palpable mass over the dorsal aspect of the distal second metacarpal bone of the left hand. The mass extended medially between the second and third metacarpals. A second small, firm, nontender left-hand mass was palpated over the volar aspect of her proximal phalanx on her index finger. She was neurovascularly intact with full active range of motion of the metacarpophalangeal and proximal and distal interphalangeal joints. There was no angular deformity of the digits. Plain radiographs taken at the time of initial presentation showed a 2.3×1.7-cm radiolucent lesion located in the metaphysis and diaphysis of the second metacarpal of the left hand (Figures 1A-1C). The lesion had varying degrees of mineralization with cortical thinning and expansion in the volar, dorsal, radial, and ulnar directions, consistent with a chondroid lesion. The second and third lesions were oval radiolucencies with sclerotic rims located at the metaphyseal-diaphyseal junction of the proximal phalanx of the index finger and middle phalanx of the middle finger, respectively. No fractures were identified in the radiographs, and the physes were open at this time. The patient was diagnosed with multiple enchondromatosis, or Ollier disease.

Our case showed 1 episode of pain and tenderness to palpation at the second proximal phalanx approximately 6 months after initial presentation. We attributed the pain and tenderness to a small pathologic fracture but did not see radiographic evidence of this. We elected to provide a trial of supportive measures, such as splinting and buddy taping, and to monitor the pain with a tentative plan of open biopsy with curettage and bone grafting if the pain persisted or evidence of fracture was seen on radiographs. The pain and tenderness to palpation resolved at a follow-up visit, and the surgery was deferred.

The patient was treated nonoperatively at initial presentation given the lack of significant cosmetic deformity or functional compromise and was advised close follow-up at 3 and 6 months. Given the absence of disease progression, annual checks (ie, clinical examination and radiographs) in a skeletally immature patient were decided on after consultation with the patient and parent. The family was educated about the possibility of pathologic fracture from minimal trauma to the hand versus the small risk of iatrogenic physeal injury with surgical curettage and bone grafting. No protective splinting was offered. A favorable prognosis and reassurance was provided to the patient and family, given the absence of symptoms, low suspicion and risk of malignant transformation, and stability of the lesion. Serial radiographs showed gradual increases in the lesions’ sizes but were consistent with the stable growth of the metacarpal and phalanges. With the patient nearing skeletal maturity, no pathologic fractures were identified on radiography during follow-up, and the risks of surgery lessened with growth; however, the continued absence of symptoms led to the mutual decision to continue observation.

Nearly 8 years after initial presentation, plain radiographs showed closed physes and partially ossified bone masses (Figures 2A-2C). The metacarpal lesion measured 3.2×1.5 cm, and the cortex appeared thickened and regular. The proximal phalanx lesion had a thickened cortex without periosteal reaction, and the middle phalanx lesion appeared to be completely healed. The patient has been asymptomatic for many years, and she has retained complete function of her left hand without any growth retardation, angular deformity, or pathologic fracture. A small but potential risk of malignant transformation was discussed with the patient and her family, as was the need for lifetime follow-up. We intend to follow the enchondromas clinically and radiographically every 2 years and obtain new radiographs if the mass presents with new clinical findings, such as enlargement or pain, for surveillance of tumor transformation. If the patient desired or symptoms developed, curettage and bone grafting would be offered, and the surgical tissue would be sent for pathologic analysis. A bone scan that was obtained at the request of the patient, when she was 21 years old, showed no other sites of disease besides the fingers.

Discussion

Multiple enchondromatosis was first described by Ollier at the turn of the 19th century and has been estimated to affect one in every 100,000 persons.¹ The low prevalence and variable manifestations of Ollier disease lead clinicians to handle the disease and its complications, namely skeletal deformity and malignant transformation, on a case-by-case approach. Additionally, the prognosis of Ollier disease with malignant transformation is quite variable, with studies reporting the estimated incidence as 5% to 50%.⁷ Muramatsu and colleagues⁶ reported that the occurrence of malignant transformation of multiple enchondromas limited to the bones of the hand was extremely rare, with only 12 cases of malignant transformation. Enchondromas of the pelvis, scapula, and long bones of the extremities have increased risks and rates of secondary transformation to chondrosarcoma.⁸

A recent large European multicenter retrospective study investigating the clinical characteristics and behavior of enchondromas in 144 patients with Ollier disease has provided new information regarding this rare disease.⁷ Verdegaal and colleagues⁷ divided patients into 3 categories depending on their distribution of enchondromas. The development of chondrosarcoma was notably different between individuals with enchondromas limited to the small bones of the hands and feet (15%, group I) versus individuals with enchondromas limited to the long bones and flat bones (43%, group II) or individuals with enchondromas of the short, long, and flat bones (46%, group III).⁷ The only location found to be statistically significant for the development of chondrosarcoma was the pelvis.

The clinical findings associated with risk of malignant transformation of enchondromas are increasing size of the lesion and onset of pain and tenderness. Dahlin and Salvador⁹ reported that only 60% of patients with chondrosarcoma of the hand experience pain. The absence of pain may lead to a delay in patient presentation to the clinician.^5,6 Radiographic findings of malignant transformation include the classic features of temporal increases in the lesion’s size after skeletal maturity and cortical destruction associated with soft-tissue invasion. However, both findings are nonspecific for differentiating enchondromas from grade 1 chondrosarcomas as described by Geirnaerdt and colleagues.¹⁰

Sassoon and colleagues¹¹ reported on a series of hand enchondromas treated operatively. Subgroup analysis between pathologic fractures treated primarily or in delayed fashion showed similar outcomes for achieving full motion and similar number of complications; however, they noted that the delayed group required 7 more weeks of immobilization. Additionally, review of the whole series showed 1 episode of metacarpal shortening and 1 occurrence of angular malalignment. In our patient, we were concerned about introducing an iatrogenic cosmetic deformity, and we believed a pathologic fracture could be managed expectantly. Overall, patients without pathologic fracture treated surgically experienced a complication rate of 12%, whereas patients with a fracture had a complication rate of 20%.¹¹ The majority of patients with multiple enchondromatosis treated with surgical curettage and grafting had successful outcomes, with 86% of patients regaining full motion, but the recurrence rate was 21%.¹¹ Patients with expansile lesions regained less motion than patients with nonexpansile lesions. There was a single lesion believed preoperatively to be an enchondroma, but it underwent malignant transformation, as confirmed on intraoperative pathology. This patient had Maffucci syndrome and was treated with an amputation through the metacarpophalangeal joint.

There are 3 options for treating hand enchondromas: observation, curettage alone, or curettage with bone grafting. There is no consensus about conservative management, timing of intervention, or risk of pathologic fracture. Each patient is treated individually with attention to reason for presentation, number of lesions, associated pain, deformity, or pathologic fracture. Operative criteria include high risk of pathologic fracture based on location of enchondroma, cortical thinning, and previous pathologic fracture with resulting angular deformity. Nonoperative management may increase the risk of pathologic fracture, particularly in patients involved in aggressive contact sports, but the physician may offer protective splinting or counsel the patient on activity modification. Our case provides a study of the natural history of multiple enchondromatosis and shows mild increases in the lesions’ sizes during the 8-year follow-up. This was an expected finding given the patient’s immature skeleton. The lesions’ cortices continued to ossify after the physes closed and now provides an excellent comparison for the identification of future malignant changes. 

Histologic analysis of biopsied or surgically treated lesions contributes to the differentiation between benign hand enchondromas and chondrosarcoma. Pathologic findings must be correlated with clinical and radiographic findings because hand enchondromas contain cytologic features of chondrosarcoma.¹² In a series of 55 patients with chondrosarcoma, Liu and colleagues⁸ reported no cases from the hand. Verdegaal and colleagues⁷ reported a total of 13 chondrosarcomas in the metacarpals and hand phalanges in 97 group I and III patients. Five of these lesions were grade 1, 2 were grade 2, 1 was grade 3, and 5 lesions were unknown.

For patients with multiple enchondromatosis limited to the hands, prognosis is relatively good with respect to risk of secondary chondrosarcoma transformation, metastasis of secondary chondrosarcoma, and death. Verdegaal and colleagues⁷ reported the rate of secondary transformation in the hand to be 15%. Patil and colleagues¹³ reported no distant metastases in 23 patients with hand chondrosarcoma at mean follow-up of 8.5 years (range, 2-19 years), although none of their patients had Ollier disease. Verdegaal and colleagues⁷ reported 7 of the 8 deaths in their study were related to development of pulmonary metastases; however, none originated from chondrosarcomas in the hand. Additionally, there were no disease-related deaths in 29 group I patients. Herget and colleagues,¹⁴ in summarizing the literature, postulated that the overall survival rate of patients with secondary chondrosarcoma at 5 years is approximately 90%.

In our case, the patient, who had 3 enchondromas isolated to the left hand, can be categorized in group I. Thus, this case highlights the natural history of a patient with hand enchondromas and demonstrates that enchondromatosis of the short tubular bones of the hands can mature and ossify.

Ollier disease, or multiple enchondromatosis, is a rare nonfamilial condition characterized by multiple cartilaginous tumors often beginning in early childhood. There is significant variation in disease distribution, location, size, number of lesions, and behavior, but the tumors are often located unilaterally.¹ Enchondromas are most commonly found in the metacarpals, metatarsals, and phalanges, and develop from metaphyseal bone in close proximity to the physis. They frequently present as painless masses or are incidentally noted during the evaluation of another musculoskeletal condition. Radiographically, enchondromas of the hands and feet appear as oval radiolucencies with thinned, sclerotic rims. The lesions have varying degrees of mineralization and endosteal scalloping, and may expand the bone.² Enchondromas usually enlarge until skeletal maturity and have been observed to ossify spontaneously.^1,3 The clinical course of Ollier disease is variable, and a number of cases of significant hand deformity and malignant transformation have been reported.^4-6

In this case report, we present a mild form of Ollier disease isolated to the patient’s left hand, which we followed for 8 years, demonstrating part of the natural history of these lesions. We discuss the patient’s clinical features, radiologic findings, diagnosis, treatment, prognosis, and follow-up, as well as review the literature. The patient and the patient’s family provided written informed consent for print and electronic publication of this case report.

Case Report

A 10-year-old, right-handed girl was referred to our department for the evaluation of left-hand masses. At age 3 years, the patient underwent a chondroma excision from the middle phalanx of her middle finger on her left hand. No operative or pathology report was available from this surgery, and the patient tolerated the procedure well without any complications. At the time of presentation, the masses did not cause any pain, motor or sensory dysfunction, or any systemic symptoms. No history of recent or distant trauma was elicited. The patient’s medical and family history was unremarkable.

On physical examination, there was a firm, immobile, nontender palpable mass over the dorsal aspect of the distal second metacarpal bone of the left hand. The mass extended medially between the second and third metacarpals. A second small, firm, nontender left-hand mass was palpated over the volar aspect of her proximal phalanx on her index finger. She was neurovascularly intact with full active range of motion of the metacarpophalangeal and proximal and distal interphalangeal joints. There was no angular deformity of the digits. Plain radiographs taken at the time of initial presentation showed a 2.3×1.7-cm radiolucent lesion located in the metaphysis and diaphysis of the second metacarpal of the left hand (Figures 1A-1C). The lesion had varying degrees of mineralization with cortical thinning and expansion in the volar, dorsal, radial, and ulnar directions, consistent with a chondroid lesion. The second and third lesions were oval radiolucencies with sclerotic rims located at the metaphyseal-diaphyseal junction of the proximal phalanx of the index finger and middle phalanx of the middle finger, respectively. No fractures were identified in the radiographs, and the physes were open at this time. The patient was diagnosed with multiple enchondromatosis, or Ollier disease.

Our case showed 1 episode of pain and tenderness to palpation at the second proximal phalanx approximately 6 months after initial presentation. We attributed the pain and tenderness to a small pathologic fracture but did not see radiographic evidence of this. We elected to provide a trial of supportive measures, such as splinting and buddy taping, and to monitor the pain with a tentative plan of open biopsy with curettage and bone grafting if the pain persisted or evidence of fracture was seen on radiographs. The pain and tenderness to palpation resolved at a follow-up visit, and the surgery was deferred.

The patient was treated nonoperatively at initial presentation given the lack of significant cosmetic deformity or functional compromise and was advised close follow-up at 3 and 6 months. Given the absence of disease progression, annual checks (ie, clinical examination and radiographs) in a skeletally immature patient were decided on after consultation with the patient and parent. The family was educated about the possibility of pathologic fracture from minimal trauma to the hand versus the small risk of iatrogenic physeal injury with surgical curettage and bone grafting. No protective splinting was offered. A favorable prognosis and reassurance was provided to the patient and family, given the absence of symptoms, low suspicion and risk of malignant transformation, and stability of the lesion. Serial radiographs showed gradual increases in the lesions’ sizes but were consistent with the stable growth of the metacarpal and phalanges. With the patient nearing skeletal maturity, no pathologic fractures were identified on radiography during follow-up, and the risks of surgery lessened with growth; however, the continued absence of symptoms led to the mutual decision to continue observation.

Nearly 8 years after initial presentation, plain radiographs showed closed physes and partially ossified bone masses (Figures 2A-2C). The metacarpal lesion measured 3.2×1.5 cm, and the cortex appeared thickened and regular. The proximal phalanx lesion had a thickened cortex without periosteal reaction, and the middle phalanx lesion appeared to be completely healed. The patient has been asymptomatic for many years, and she has retained complete function of her left hand without any growth retardation, angular deformity, or pathologic fracture. A small but potential risk of malignant transformation was discussed with the patient and her family, as was the need for lifetime follow-up. We intend to follow the enchondromas clinically and radiographically every 2 years and obtain new radiographs if the mass presents with new clinical findings, such as enlargement or pain, for surveillance of tumor transformation. If the patient desired or symptoms developed, curettage and bone grafting would be offered, and the surgical tissue would be sent for pathologic analysis. A bone scan that was obtained at the request of the patient, when she was 21 years old, showed no other sites of disease besides the fingers.

Discussion

Multiple enchondromatosis was first described by Ollier at the turn of the 19th century and has been estimated to affect one in every 100,000 persons.¹ The low prevalence and variable manifestations of Ollier disease lead clinicians to handle the disease and its complications, namely skeletal deformity and malignant transformation, on a case-by-case approach. Additionally, the prognosis of Ollier disease with malignant transformation is quite variable, with studies reporting the estimated incidence as 5% to 50%.⁷ Muramatsu and colleagues⁶ reported that the occurrence of malignant transformation of multiple enchondromas limited to the bones of the hand was extremely rare, with only 12 cases of malignant transformation. Enchondromas of the pelvis, scapula, and long bones of the extremities have increased risks and rates of secondary transformation to chondrosarcoma.⁸

A recent large European multicenter retrospective study investigating the clinical characteristics and behavior of enchondromas in 144 patients with Ollier disease has provided new information regarding this rare disease.⁷ Verdegaal and colleagues⁷ divided patients into 3 categories depending on their distribution of enchondromas. The development of chondrosarcoma was notably different between individuals with enchondromas limited to the small bones of the hands and feet (15%, group I) versus individuals with enchondromas limited to the long bones and flat bones (43%, group II) or individuals with enchondromas of the short, long, and flat bones (46%, group III).⁷ The only location found to be statistically significant for the development of chondrosarcoma was the pelvis.

The clinical findings associated with risk of malignant transformation of enchondromas are increasing size of the lesion and onset of pain and tenderness. Dahlin and Salvador⁹ reported that only 60% of patients with chondrosarcoma of the hand experience pain. The absence of pain may lead to a delay in patient presentation to the clinician.^5,6 Radiographic findings of malignant transformation include the classic features of temporal increases in the lesion’s size after skeletal maturity and cortical destruction associated with soft-tissue invasion. However, both findings are nonspecific for differentiating enchondromas from grade 1 chondrosarcomas as described by Geirnaerdt and colleagues.¹⁰

Sassoon and colleagues¹¹ reported on a series of hand enchondromas treated operatively. Subgroup analysis between pathologic fractures treated primarily or in delayed fashion showed similar outcomes for achieving full motion and similar number of complications; however, they noted that the delayed group required 7 more weeks of immobilization. Additionally, review of the whole series showed 1 episode of metacarpal shortening and 1 occurrence of angular malalignment. In our patient, we were concerned about introducing an iatrogenic cosmetic deformity, and we believed a pathologic fracture could be managed expectantly. Overall, patients without pathologic fracture treated surgically experienced a complication rate of 12%, whereas patients with a fracture had a complication rate of 20%.¹¹ The majority of patients with multiple enchondromatosis treated with surgical curettage and grafting had successful outcomes, with 86% of patients regaining full motion, but the recurrence rate was 21%.¹¹ Patients with expansile lesions regained less motion than patients with nonexpansile lesions. There was a single lesion believed preoperatively to be an enchondroma, but it underwent malignant transformation, as confirmed on intraoperative pathology. This patient had Maffucci syndrome and was treated with an amputation through the metacarpophalangeal joint.

There are 3 options for treating hand enchondromas: observation, curettage alone, or curettage with bone grafting. There is no consensus about conservative management, timing of intervention, or risk of pathologic fracture. Each patient is treated individually with attention to reason for presentation, number of lesions, associated pain, deformity, or pathologic fracture. Operative criteria include high risk of pathologic fracture based on location of enchondroma, cortical thinning, and previous pathologic fracture with resulting angular deformity. Nonoperative management may increase the risk of pathologic fracture, particularly in patients involved in aggressive contact sports, but the physician may offer protective splinting or counsel the patient on activity modification. Our case provides a study of the natural history of multiple enchondromatosis and shows mild increases in the lesions’ sizes during the 8-year follow-up. This was an expected finding given the patient’s immature skeleton. The lesions’ cortices continued to ossify after the physes closed and now provides an excellent comparison for the identification of future malignant changes. 

Histologic analysis of biopsied or surgically treated lesions contributes to the differentiation between benign hand enchondromas and chondrosarcoma. Pathologic findings must be correlated with clinical and radiographic findings because hand enchondromas contain cytologic features of chondrosarcoma.¹² In a series of 55 patients with chondrosarcoma, Liu and colleagues⁸ reported no cases from the hand. Verdegaal and colleagues⁷ reported a total of 13 chondrosarcomas in the metacarpals and hand phalanges in 97 group I and III patients. Five of these lesions were grade 1, 2 were grade 2, 1 was grade 3, and 5 lesions were unknown.

For patients with multiple enchondromatosis limited to the hands, prognosis is relatively good with respect to risk of secondary chondrosarcoma transformation, metastasis of secondary chondrosarcoma, and death. Verdegaal and colleagues⁷ reported the rate of secondary transformation in the hand to be 15%. Patil and colleagues¹³ reported no distant metastases in 23 patients with hand chondrosarcoma at mean follow-up of 8.5 years (range, 2-19 years), although none of their patients had Ollier disease. Verdegaal and colleagues⁷ reported 7 of the 8 deaths in their study were related to development of pulmonary metastases; however, none originated from chondrosarcomas in the hand. Additionally, there were no disease-related deaths in 29 group I patients. Herget and colleagues,¹⁴ in summarizing the literature, postulated that the overall survival rate of patients with secondary chondrosarcoma at 5 years is approximately 90%.

In our case, the patient, who had 3 enchondromas isolated to the left hand, can be categorized in group I. Thus, this case highlights the natural history of a patient with hand enchondromas and demonstrates that enchondromatosis of the short tubular bones of the hands can mature and ossify.