Conference News Update—American Association of Neurological Surgeons

Stem Cell Transplantation Is Safe in Hemorrhagic Stroke

Intraventricular transplantation using bone marrow mesenchymal stem cells is safe in patients with hemorrhagic stroke, according to research presented by Asra Al Fauzi, MD, a neurosurgeon at Soetomo General Hospital in Surabaya, Indonesia.

This study examined a group of eight patients with supratentorial hemorrhagic stroke. All patients had received six months of treatment and had stable neurologic deficits and NIH Stroke Scale (NIHSS) scores of five to 25. Clinical outcomes were measured using the NIHSS scale six months after transplantation. Bone marrow was aspirated and taken from the patient to whom it was to be administered under aseptic conditions. Expansion of mesenchymal stem cells took three to four weeks. All patients were administered a mean of 20 × 106 cells intraventricularly.

Results showed improvement of the NIHSS score in five patients after treatment; three patients had no change in status. No important adverse events associated with transplant or surgery were observed during a six-month follow up. The study demonstrates that bone marrow mesenchymal stem cell can be transplanted intraventricularly with excellent tolerance and without complications, said Dr. Al Fauzi. Stem cell transplantation aiming to restore function in stroke is safe and feasible. Further randomized controlled trials are needed to evaluate its efficacy.

How Does Surgery for Cerebral Arteriovenous Malformation Affect Pulsatility and Resistance?

Embolization reduces flow in cerebral arteriovenous malformations (AVMs) before surgical resection, but changes in pulsatility index (PI) and resistance index (RI) are unknown. Sophia F. Shakur, MD, a neurosurgery resident at the University of Chicago Medical Center, and colleagues measured PI and RI in AVM arterial feeders before and after embolization or surgery.

The researchers reviewed the records of patients who underwent AVM embolization and surgical resection at a single institution between 2007 and 2014.Patients who had PI, RI, and flows obtained using quantitative magnetic resonance angiography were retrospectively reviewed. Hemodynamic parameters were compared between the feeder and contralateral artery before and after embolization or surgery.

Thirty-two patients with 48 feeder arteries underwent embolization (mean 1.3 sessions). Another 32 patients with 49 feeder arteries had surgery with or without preoperative embolization. Before treatment, flow volume rate and mean, systolic and diastolic flow velocities were significantly higher in feeders versus contralateral counterparts. PI and RI were significantly lower in feeder vessels, compared with contralateral vessels. After embolization, mean, systolic, and diastolic flow velocities increased significantly, but PI and RI did not change significantly. However, after surgery, mean, systolic, and diastolic flow velocities within feeders decreased significantly, and PI and RI normalized to match the indices of their contralateral counterparts.

Following partial AVM embolization, PI and RI were unchanged, and flow velocities in feeder arteries increased significantly, likely due to redistribution of flow through residual nidus. Complete surgical resection resulted in normalization of PI and RI and a concomitant decrease in flow velocities.

Temporal Evolution of ICP and PRx May Have Prognostic Significance

Studies of large cohorts of patients with traumatic brain injury (TBI) have shown that intracranial pressure (ICP) and the pressure reactivity index (PRx) are independently associated with patient outcome. How these parameters evolve over the course of the stay in an intensive care unit, and the question of whether this evolution has any prognostic importance, has not been well studied, however.

Hadie Adams, MD, a postdoctoral fellow at Johns Hopkins School of Medicine in Baltimore, and colleagues monitored ICP and PRx in 573 patients with severe TBI in a regional neurocritical care unit. Data were calculated in 12-hour epochs for the first 168 hours (ie, seven days) after the time of incident. Data were stratified by the presence of diffuse TBI (dTBI) or space occupying lesions (SOL), as well as by fatal or nonfatal outcome at six months post injury. Mixed linear modeling was used to assess change of ICP and PRx over time to detect differences in mortality.

Mean ICP peaked at between 24 hours and 36 hours after injury, but only in patients who died. The difference in mean ICP between patients with fatal and nonfatal outcome was significant for the first 120 hours after ictus. For PRx, patients with a fatal outcome also had higher (ie, more impaired) PRx throughout the first 168 hours after ictus. The separation of ICP and PRx was greatest in the first 72 hours after ictus. Also, mean differences of ICP and PRx between the outcome groups were more pronounced in patients with dTBI than those with SOL.

In this cohort of 573 patients with TBI and high-resolution physiologic data, ICP and PRx displayed a distinctive temporal evolution. Importantly, early ICP and PRx allowed for the clearest prognostic delineation, said Dr. Adams.

The optimal thresholds, prognostic significance, and clinical correlations of ICP and PRx are likely to be time-dependent, he added.

How Common Is Position-Related Neuropraxia In Spine Surgery?

Gurpreet Surinder Gandhoke, MD, a neurosurgeon in Pittsburgh, and colleagues examined the incidence of position-related neuropraxia in 4,489 consecutive patients undergoing spine surgery at a university hospital. Some patients in the group had peripheral nerve injury from positioning. The authors observed intraoperative monitoring (IOM) changes related to arm and leg positioning and calculated their sensitivity and specificity in predicting the development of a new position-related peripheral nerve injury. Impact of length of surgery and other variables, including age, sex, BMI, diabetes, hypertension, coronary artery disease, cardiovascular disease, and a history of smoking on the development of a new peripheral nerve injury were defined.

Patients were in the following positions: arms abducted and flexed at the elbow (64.7%), arms tucked at the side (35%), and the lateral position (0.3%). Thirteen of 4,489 patients developed a new positioning-related peripheral nerve deficit, 54% developed meralgia paresthetica, and 46% developed ulnar neuropathy.

Seventy-two patients (1.6%) developed IOM changes from positioning, and all of these patients underwent a repositioning maneuver. One of these 72 patients (1.3%) developed a new position-related nerve deficit. Of the 98.4% of patients who did not develop position-related IOM changes, 0.3% developed a new position-related nerve deficit.

Sensitivity of IOM to detect a new position-related nerve deficit was 7.69%, and the specificity was 98.41%. Neither length of surgery nor any analyzed patient-related variable significantly affected the development of a new neuropraxia. The incidence of a new position-related nerve deficit in spine surgery was less than 0.3%. IOM had high specificity and low sensitivity in detecting a positioning-related deficit.

Stem Cell Transplantation Is Safe in Hemorrhagic Stroke

Intraventricular transplantation using bone marrow mesenchymal stem cells is safe in patients with hemorrhagic stroke, according to research presented by Asra Al Fauzi, MD, a neurosurgeon at Soetomo General Hospital in Surabaya, Indonesia.

This study examined a group of eight patients with supratentorial hemorrhagic stroke. All patients had received six months of treatment and had stable neurologic deficits and NIH Stroke Scale (NIHSS) scores of five to 25. Clinical outcomes were measured using the NIHSS scale six months after transplantation. Bone marrow was aspirated and taken from the patient to whom it was to be administered under aseptic conditions. Expansion of mesenchymal stem cells took three to four weeks. All patients were administered a mean of 20 × 106 cells intraventricularly.

Results showed improvement of the NIHSS score in five patients after treatment; three patients had no change in status. No important adverse events associated with transplant or surgery were observed during a six-month follow up. The study demonstrates that bone marrow mesenchymal stem cell can be transplanted intraventricularly with excellent tolerance and without complications, said Dr. Al Fauzi. Stem cell transplantation aiming to restore function in stroke is safe and feasible. Further randomized controlled trials are needed to evaluate its efficacy.

How Does Surgery for Cerebral Arteriovenous Malformation Affect Pulsatility and Resistance?

Embolization reduces flow in cerebral arteriovenous malformations (AVMs) before surgical resection, but changes in pulsatility index (PI) and resistance index (RI) are unknown. Sophia F. Shakur, MD, a neurosurgery resident at the University of Chicago Medical Center, and colleagues measured PI and RI in AVM arterial feeders before and after embolization or surgery.

The researchers reviewed the records of patients who underwent AVM embolization and surgical resection at a single institution between 2007 and 2014.Patients who had PI, RI, and flows obtained using quantitative magnetic resonance angiography were retrospectively reviewed. Hemodynamic parameters were compared between the feeder and contralateral artery before and after embolization or surgery.

Thirty-two patients with 48 feeder arteries underwent embolization (mean 1.3 sessions). Another 32 patients with 49 feeder arteries had surgery with or without preoperative embolization. Before treatment, flow volume rate and mean, systolic and diastolic flow velocities were significantly higher in feeders versus contralateral counterparts. PI and RI were significantly lower in feeder vessels, compared with contralateral vessels. After embolization, mean, systolic, and diastolic flow velocities increased significantly, but PI and RI did not change significantly. However, after surgery, mean, systolic, and diastolic flow velocities within feeders decreased significantly, and PI and RI normalized to match the indices of their contralateral counterparts.

Following partial AVM embolization, PI and RI were unchanged, and flow velocities in feeder arteries increased significantly, likely due to redistribution of flow through residual nidus. Complete surgical resection resulted in normalization of PI and RI and a concomitant decrease in flow velocities.

Temporal Evolution of ICP and PRx May Have Prognostic Significance

Studies of large cohorts of patients with traumatic brain injury (TBI) have shown that intracranial pressure (ICP) and the pressure reactivity index (PRx) are independently associated with patient outcome. How these parameters evolve over the course of the stay in an intensive care unit, and the question of whether this evolution has any prognostic importance, has not been well studied, however.

Hadie Adams, MD, a postdoctoral fellow at Johns Hopkins School of Medicine in Baltimore, and colleagues monitored ICP and PRx in 573 patients with severe TBI in a regional neurocritical care unit. Data were calculated in 12-hour epochs for the first 168 hours (ie, seven days) after the time of incident. Data were stratified by the presence of diffuse TBI (dTBI) or space occupying lesions (SOL), as well as by fatal or nonfatal outcome at six months post injury. Mixed linear modeling was used to assess change of ICP and PRx over time to detect differences in mortality.

Mean ICP peaked at between 24 hours and 36 hours after injury, but only in patients who died. The difference in mean ICP between patients with fatal and nonfatal outcome was significant for the first 120 hours after ictus. For PRx, patients with a fatal outcome also had higher (ie, more impaired) PRx throughout the first 168 hours after ictus. The separation of ICP and PRx was greatest in the first 72 hours after ictus. Also, mean differences of ICP and PRx between the outcome groups were more pronounced in patients with dTBI than those with SOL.

In this cohort of 573 patients with TBI and high-resolution physiologic data, ICP and PRx displayed a distinctive temporal evolution. Importantly, early ICP and PRx allowed for the clearest prognostic delineation, said Dr. Adams.

The optimal thresholds, prognostic significance, and clinical correlations of ICP and PRx are likely to be time-dependent, he added.

How Common Is Position-Related Neuropraxia In Spine Surgery?

Gurpreet Surinder Gandhoke, MD, a neurosurgeon in Pittsburgh, and colleagues examined the incidence of position-related neuropraxia in 4,489 consecutive patients undergoing spine surgery at a university hospital. Some patients in the group had peripheral nerve injury from positioning. The authors observed intraoperative monitoring (IOM) changes related to arm and leg positioning and calculated their sensitivity and specificity in predicting the development of a new position-related peripheral nerve injury. Impact of length of surgery and other variables, including age, sex, BMI, diabetes, hypertension, coronary artery disease, cardiovascular disease, and a history of smoking on the development of a new peripheral nerve injury were defined.

Patients were in the following positions: arms abducted and flexed at the elbow (64.7%), arms tucked at the side (35%), and the lateral position (0.3%). Thirteen of 4,489 patients developed a new positioning-related peripheral nerve deficit, 54% developed meralgia paresthetica, and 46% developed ulnar neuropathy.

Seventy-two patients (1.6%) developed IOM changes from positioning, and all of these patients underwent a repositioning maneuver. One of these 72 patients (1.3%) developed a new position-related nerve deficit. Of the 98.4% of patients who did not develop position-related IOM changes, 0.3% developed a new position-related nerve deficit.

Sensitivity of IOM to detect a new position-related nerve deficit was 7.69%, and the specificity was 98.41%. Neither length of surgery nor any analyzed patient-related variable significantly affected the development of a new neuropraxia. The incidence of a new position-related nerve deficit in spine surgery was less than 0.3%. IOM had high specificity and low sensitivity in detecting a positioning-related deficit.

Stem Cell Transplantation Is Safe in Hemorrhagic Stroke

Intraventricular transplantation using bone marrow mesenchymal stem cells is safe in patients with hemorrhagic stroke, according to research presented by Asra Al Fauzi, MD, a neurosurgeon at Soetomo General Hospital in Surabaya, Indonesia.

This study examined a group of eight patients with supratentorial hemorrhagic stroke. All patients had received six months of treatment and had stable neurologic deficits and NIH Stroke Scale (NIHSS) scores of five to 25. Clinical outcomes were measured using the NIHSS scale six months after transplantation. Bone marrow was aspirated and taken from the patient to whom it was to be administered under aseptic conditions. Expansion of mesenchymal stem cells took three to four weeks. All patients were administered a mean of 20 × 106 cells intraventricularly.

Results showed improvement of the NIHSS score in five patients after treatment; three patients had no change in status. No important adverse events associated with transplant or surgery were observed during a six-month follow up. The study demonstrates that bone marrow mesenchymal stem cell can be transplanted intraventricularly with excellent tolerance and without complications, said Dr. Al Fauzi. Stem cell transplantation aiming to restore function in stroke is safe and feasible. Further randomized controlled trials are needed to evaluate its efficacy.

How Does Surgery for Cerebral Arteriovenous Malformation Affect Pulsatility and Resistance?

Embolization reduces flow in cerebral arteriovenous malformations (AVMs) before surgical resection, but changes in pulsatility index (PI) and resistance index (RI) are unknown. Sophia F. Shakur, MD, a neurosurgery resident at the University of Chicago Medical Center, and colleagues measured PI and RI in AVM arterial feeders before and after embolization or surgery.

The researchers reviewed the records of patients who underwent AVM embolization and surgical resection at a single institution between 2007 and 2014.Patients who had PI, RI, and flows obtained using quantitative magnetic resonance angiography were retrospectively reviewed. Hemodynamic parameters were compared between the feeder and contralateral artery before and after embolization or surgery.

Thirty-two patients with 48 feeder arteries underwent embolization (mean 1.3 sessions). Another 32 patients with 49 feeder arteries had surgery with or without preoperative embolization. Before treatment, flow volume rate and mean, systolic and diastolic flow velocities were significantly higher in feeders versus contralateral counterparts. PI and RI were significantly lower in feeder vessels, compared with contralateral vessels. After embolization, mean, systolic, and diastolic flow velocities increased significantly, but PI and RI did not change significantly. However, after surgery, mean, systolic, and diastolic flow velocities within feeders decreased significantly, and PI and RI normalized to match the indices of their contralateral counterparts.

Following partial AVM embolization, PI and RI were unchanged, and flow velocities in feeder arteries increased significantly, likely due to redistribution of flow through residual nidus. Complete surgical resection resulted in normalization of PI and RI and a concomitant decrease in flow velocities.

Temporal Evolution of ICP and PRx May Have Prognostic Significance

Studies of large cohorts of patients with traumatic brain injury (TBI) have shown that intracranial pressure (ICP) and the pressure reactivity index (PRx) are independently associated with patient outcome. How these parameters evolve over the course of the stay in an intensive care unit, and the question of whether this evolution has any prognostic importance, has not been well studied, however.

Hadie Adams, MD, a postdoctoral fellow at Johns Hopkins School of Medicine in Baltimore, and colleagues monitored ICP and PRx in 573 patients with severe TBI in a regional neurocritical care unit. Data were calculated in 12-hour epochs for the first 168 hours (ie, seven days) after the time of incident. Data were stratified by the presence of diffuse TBI (dTBI) or space occupying lesions (SOL), as well as by fatal or nonfatal outcome at six months post injury. Mixed linear modeling was used to assess change of ICP and PRx over time to detect differences in mortality.

Mean ICP peaked at between 24 hours and 36 hours after injury, but only in patients who died. The difference in mean ICP between patients with fatal and nonfatal outcome was significant for the first 120 hours after ictus. For PRx, patients with a fatal outcome also had higher (ie, more impaired) PRx throughout the first 168 hours after ictus. The separation of ICP and PRx was greatest in the first 72 hours after ictus. Also, mean differences of ICP and PRx between the outcome groups were more pronounced in patients with dTBI than those with SOL.

In this cohort of 573 patients with TBI and high-resolution physiologic data, ICP and PRx displayed a distinctive temporal evolution. Importantly, early ICP and PRx allowed for the clearest prognostic delineation, said Dr. Adams.

The optimal thresholds, prognostic significance, and clinical correlations of ICP and PRx are likely to be time-dependent, he added.

How Common Is Position-Related Neuropraxia In Spine Surgery?

Gurpreet Surinder Gandhoke, MD, a neurosurgeon in Pittsburgh, and colleagues examined the incidence of position-related neuropraxia in 4,489 consecutive patients undergoing spine surgery at a university hospital. Some patients in the group had peripheral nerve injury from positioning. The authors observed intraoperative monitoring (IOM) changes related to arm and leg positioning and calculated their sensitivity and specificity in predicting the development of a new position-related peripheral nerve injury. Impact of length of surgery and other variables, including age, sex, BMI, diabetes, hypertension, coronary artery disease, cardiovascular disease, and a history of smoking on the development of a new peripheral nerve injury were defined.

Patients were in the following positions: arms abducted and flexed at the elbow (64.7%), arms tucked at the side (35%), and the lateral position (0.3%). Thirteen of 4,489 patients developed a new positioning-related peripheral nerve deficit, 54% developed meralgia paresthetica, and 46% developed ulnar neuropathy.

Seventy-two patients (1.6%) developed IOM changes from positioning, and all of these patients underwent a repositioning maneuver. One of these 72 patients (1.3%) developed a new position-related nerve deficit. Of the 98.4% of patients who did not develop position-related IOM changes, 0.3% developed a new position-related nerve deficit.

Sensitivity of IOM to detect a new position-related nerve deficit was 7.69%, and the specificity was 98.41%. Neither length of surgery nor any analyzed patient-related variable significantly affected the development of a new neuropraxia. The incidence of a new position-related nerve deficit in spine surgery was less than 0.3%. IOM had high specificity and low sensitivity in detecting a positioning-related deficit.