Literature Monitor

Stroke After Cardiac Surgery and Role of Carotid Stenosis
Combining carotid and cardiac procedures is neither necessary nor effective in reducing postoperative stroke in patients with asymptomatic carotid stenosis, according to a study in the September Archives of Neurology. Researchers found no direct causal relationship between significant carotid stenosis and postoperative stroke in patients who underwent cardiac operations.

Yuebing Li, MD, PhD, and colleagues at Lehigh Valley Hospital and Health Network in Allentown, Pennsylvania, reviewed data of 4,335 patients receiving nonurgent coronary artery bypass grafting (CABG) and/or aortic valve replacement between July 2001 and December 2006. Prior to surgery, 3,942 patients were evaluated for carotid stenosis using high-resolution sonography, 239 (6.1%) of whom were identified as having significant carotid stenosis.

A total of 76 patients (1.8%) had a clinically definitive stroke following surgery. Of those, 18 patients had significant carotid stenosis (23.7%). Although stroke was more common in individuals with carotid stenosis than in those without (7.5% vs 1.8%), 14 of the 18 strokes “occurred outside the territory of diseased carotid artery,” the study authors noted. Furthermore, the majority (76.3%) of postoperative strokes occurred in individuals without carotid disease, and 60% of the strokes were not confined to a single carotid artery.

“According to clinical data, in 94.7% of patients, stroke occurred without direct correlation to significant carotid stenosis,” the study authors wrote. “This study strongly suggests there is no direct causal relationship between postoperative stroke and severe carotid stenosis.”

In a related editorial, Louis R. Caplan, MD, Professor of Neurology at Harvard Medical School in Boston, commented on the neurologic complications of elective coronary artery surgery. “Processes that include checklists and time-outs during which the team reviews findings and strategies have led to reduced medical errors and improved outcomes,” Dr. Caplan wrote. “I suggest that patients and preoperative information should be reviewed before surgery by a team approach that includes a cardiologist who will observe the patients throughout their hospitalization and the cardiac surgeon who will perform the operation.”
Li Y, Walicki D, Mathiesen C, et al. Strokes after cardiac surgery and relationship to carotid stenosis. Arch Neurol. 2009;66(9):1091-1096.
Caplan LR. Translating what is known about neurological complications of coronary artery bypass graft surgery into action. Arch Neurol. 2009;66(9):1062-1064.

CT Scans in Children With Head Injury
Researchers have identified guidelines for accurately predicting children at very low risk of clinically important traumatic brain injuries (TBI), for whom CT scans should be avoided, as reported in the September 15 online Lancet. Nathan Kuppermann, MD, of the University of California-Davis School of Medicine in Sacramento, and colleagues analyzed 42,412 children with head trauma in 25 North American emergency departments, and derived and validated age-specific prediction rules for clinically important TBI. Application of these rules, the investigators believe, could limit CT use, protecting children from unnecessary radiation risks.

Dr. Kuppermann’s group, the Pediatric Emergency Care Applied Research Network, identified the following algorithms with 100% and 99.95% negative predictive value for clinically important TBI, respectively:

• For children younger than 2, normal mental status, no scalp hematoma except frontal, no loss of consciousness or loss of consciousness for less than 5 seconds, nonsevere injury mechanism, no palpable skull fracture, and acting normally according to the parents.
• For children 2 and older, normal mental status, no loss of consciousness, no vomiting, nonsevere injury mechanism, no signs of basilar skull fracture, and no severe headache.

“Data to guide clinical decision making for children with head trauma are urgently needed because head trauma is common and CT use is increasing,” the study authors commented. “Children sustaining minor head trauma infrequently have TBI and rarely need neurosurgery. The small risk of clinically important TBI should be balanced against the risks of ionizing radiation of CTs.”

“Kuppermann and colleagues remind us that the rules are meant to inform clinical decision making, not to replace it,” Patricia C. Parkin, MD, and Jonathon L. Maguire, MD, of the Division of Pediatric Medicine and the Pediatric Outcomes Research Team at the Hospital for Sick Children in Toronto, wrote in an accompanying comment. “The next challenge for evidence-based medicine is knowledge translation. Decision aids might provide structured presentations of options and outcomes.”
Kuppermann N, Holmes JF, Dayan PS, et al. Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study. Lancet. 2009 Sep 14; [Epub ahead of print].
Parkin PC, Maguire JL. Clinically important head injuries after head trauma in children. Lancet. 2009 Sep 14; [Epub ahead of print].

Parent-of-Origin Effects in MS
The greater female-to-male ratio in patients with multiple sclerosis (MS) appears to be more strongly related to the mother, a study published in the August 25 Neurology reported. This maternal parent-of-origin effect, previously seen in studies of half-siblings and avuncular pairs, was found in offspring from a Caucasian mother and North American Aboriginal father.

S.V. Ramagopalan, DPhil, of the Wellcome Trust Centre for Human Genetics at the University of Oxford, UK, and colleagues examined 30,000 MS cases from the Canadian Collaborative Project on Genetic Susceptibility to Multiple Sclerosis (CCPGSMS) and identified 58 individuals with one Caucasian parent and one North American Aboriginal parent. Of these, 27 had a Caucasian mother and 31 had a North American Aboriginal mother. Although the total number of affected offspring was similar in the two mating types studied, the sex ratio differed. Female-to-male sex ratio was 7:1 for patients with MS who had a Caucasian mother, compared with a 2:1 ratio for those with a Caucasian father.

“A parent-of-origin effect (maternal) has been repeatedly observed in MS, based on studies of half-siblings, sibships including dizygotic twins, a large extended Dutch pedigree, and avuncular pairs, as well as timing of birth effect,” the study authors noted. “The comparison of offspring from interracial matings is a novel method of analysis to look for parent of origin effects.

“The data from this study hint at an intriguing possibility that the observed female preponderance of MS could result from environmental factors acting upon mothers to differentially affect MS risk more in female than in male offspring,” the researchers pointed out.

In a related editorial, John W. Rose, MD, commented that this study “illustrated the continued potential of the CCPGSMS to address interesting questions related to the disease.… By evaluating a small set of MS patients with a Caucasian parent and a Native Aboriginal American parent, the investigators were able to assess parental effects on the disease,” he continued. “The susceptibility to disease is presumed to be predominantly introduced by the Caucasian parent based on previous investigations. In this admixture study, the results demonstrate a maternal effect which strongly influences the sex ratio of offspring affected by MS, linking these two classes of gender differences in MS.”
Ramagopalan SV, Yee IM, Dyment DA, et al. Parent-of-origin effect in multiple sclerosis: observations from interracial matings. Neurology. 2009;73(8):602-605.
Rose JW. Multiple sclerosis: evidence of maternal effects and an increasing incidence in women. Neurology. 2009;73(8):578-579.

Stroke After Cardiac Surgery and Role of Carotid Stenosis
Combining carotid and cardiac procedures is neither necessary nor effective in reducing postoperative stroke in patients with asymptomatic carotid stenosis, according to a study in the September Archives of Neurology. Researchers found no direct causal relationship between significant carotid stenosis and postoperative stroke in patients who underwent cardiac operations.

Yuebing Li, MD, PhD, and colleagues at Lehigh Valley Hospital and Health Network in Allentown, Pennsylvania, reviewed data of 4,335 patients receiving nonurgent coronary artery bypass grafting (CABG) and/or aortic valve replacement between July 2001 and December 2006. Prior to surgery, 3,942 patients were evaluated for carotid stenosis using high-resolution sonography, 239 (6.1%) of whom were identified as having significant carotid stenosis.

A total of 76 patients (1.8%) had a clinically definitive stroke following surgery. Of those, 18 patients had significant carotid stenosis (23.7%). Although stroke was more common in individuals with carotid stenosis than in those without (7.5% vs 1.8%), 14 of the 18 strokes “occurred outside the territory of diseased carotid artery,” the study authors noted. Furthermore, the majority (76.3%) of postoperative strokes occurred in individuals without carotid disease, and 60% of the strokes were not confined to a single carotid artery.

“According to clinical data, in 94.7% of patients, stroke occurred without direct correlation to significant carotid stenosis,” the study authors wrote. “This study strongly suggests there is no direct causal relationship between postoperative stroke and severe carotid stenosis.”

In a related editorial, Louis R. Caplan, MD, Professor of Neurology at Harvard Medical School in Boston, commented on the neurologic complications of elective coronary artery surgery. “Processes that include checklists and time-outs during which the team reviews findings and strategies have led to reduced medical errors and improved outcomes,” Dr. Caplan wrote. “I suggest that patients and preoperative information should be reviewed before surgery by a team approach that includes a cardiologist who will observe the patients throughout their hospitalization and the cardiac surgeon who will perform the operation.”
Li Y, Walicki D, Mathiesen C, et al. Strokes after cardiac surgery and relationship to carotid stenosis. Arch Neurol. 2009;66(9):1091-1096.
Caplan LR. Translating what is known about neurological complications of coronary artery bypass graft surgery into action. Arch Neurol. 2009;66(9):1062-1064.

CT Scans in Children With Head Injury
Researchers have identified guidelines for accurately predicting children at very low risk of clinically important traumatic brain injuries (TBI), for whom CT scans should be avoided, as reported in the September 15 online Lancet. Nathan Kuppermann, MD, of the University of California-Davis School of Medicine in Sacramento, and colleagues analyzed 42,412 children with head trauma in 25 North American emergency departments, and derived and validated age-specific prediction rules for clinically important TBI. Application of these rules, the investigators believe, could limit CT use, protecting children from unnecessary radiation risks.

Dr. Kuppermann’s group, the Pediatric Emergency Care Applied Research Network, identified the following algorithms with 100% and 99.95% negative predictive value for clinically important TBI, respectively:

• For children younger than 2, normal mental status, no scalp hematoma except frontal, no loss of consciousness or loss of consciousness for less than 5 seconds, nonsevere injury mechanism, no palpable skull fracture, and acting normally according to the parents.
• For children 2 and older, normal mental status, no loss of consciousness, no vomiting, nonsevere injury mechanism, no signs of basilar skull fracture, and no severe headache.

“Data to guide clinical decision making for children with head trauma are urgently needed because head trauma is common and CT use is increasing,” the study authors commented. “Children sustaining minor head trauma infrequently have TBI and rarely need neurosurgery. The small risk of clinically important TBI should be balanced against the risks of ionizing radiation of CTs.”

“Kuppermann and colleagues remind us that the rules are meant to inform clinical decision making, not to replace it,” Patricia C. Parkin, MD, and Jonathon L. Maguire, MD, of the Division of Pediatric Medicine and the Pediatric Outcomes Research Team at the Hospital for Sick Children in Toronto, wrote in an accompanying comment. “The next challenge for evidence-based medicine is knowledge translation. Decision aids might provide structured presentations of options and outcomes.”
Kuppermann N, Holmes JF, Dayan PS, et al. Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study. Lancet. 2009 Sep 14; [Epub ahead of print].
Parkin PC, Maguire JL. Clinically important head injuries after head trauma in children. Lancet. 2009 Sep 14; [Epub ahead of print].

Parent-of-Origin Effects in MS
The greater female-to-male ratio in patients with multiple sclerosis (MS) appears to be more strongly related to the mother, a study published in the August 25 Neurology reported. This maternal parent-of-origin effect, previously seen in studies of half-siblings and avuncular pairs, was found in offspring from a Caucasian mother and North American Aboriginal father.

S.V. Ramagopalan, DPhil, of the Wellcome Trust Centre for Human Genetics at the University of Oxford, UK, and colleagues examined 30,000 MS cases from the Canadian Collaborative Project on Genetic Susceptibility to Multiple Sclerosis (CCPGSMS) and identified 58 individuals with one Caucasian parent and one North American Aboriginal parent. Of these, 27 had a Caucasian mother and 31 had a North American Aboriginal mother. Although the total number of affected offspring was similar in the two mating types studied, the sex ratio differed. Female-to-male sex ratio was 7:1 for patients with MS who had a Caucasian mother, compared with a 2:1 ratio for those with a Caucasian father.

“A parent-of-origin effect (maternal) has been repeatedly observed in MS, based on studies of half-siblings, sibships including dizygotic twins, a large extended Dutch pedigree, and avuncular pairs, as well as timing of birth effect,” the study authors noted. “The comparison of offspring from interracial matings is a novel method of analysis to look for parent of origin effects.

“The data from this study hint at an intriguing possibility that the observed female preponderance of MS could result from environmental factors acting upon mothers to differentially affect MS risk more in female than in male offspring,” the researchers pointed out.

In a related editorial, John W. Rose, MD, commented that this study “illustrated the continued potential of the CCPGSMS to address interesting questions related to the disease.… By evaluating a small set of MS patients with a Caucasian parent and a Native Aboriginal American parent, the investigators were able to assess parental effects on the disease,” he continued. “The susceptibility to disease is presumed to be predominantly introduced by the Caucasian parent based on previous investigations. In this admixture study, the results demonstrate a maternal effect which strongly influences the sex ratio of offspring affected by MS, linking these two classes of gender differences in MS.”
Ramagopalan SV, Yee IM, Dyment DA, et al. Parent-of-origin effect in multiple sclerosis: observations from interracial matings. Neurology. 2009;73(8):602-605.
Rose JW. Multiple sclerosis: evidence of maternal effects and an increasing incidence in women. Neurology. 2009;73(8):578-579.

Stroke After Cardiac Surgery and Role of Carotid Stenosis
Combining carotid and cardiac procedures is neither necessary nor effective in reducing postoperative stroke in patients with asymptomatic carotid stenosis, according to a study in the September Archives of Neurology. Researchers found no direct causal relationship between significant carotid stenosis and postoperative stroke in patients who underwent cardiac operations.

Yuebing Li, MD, PhD, and colleagues at Lehigh Valley Hospital and Health Network in Allentown, Pennsylvania, reviewed data of 4,335 patients receiving nonurgent coronary artery bypass grafting (CABG) and/or aortic valve replacement between July 2001 and December 2006. Prior to surgery, 3,942 patients were evaluated for carotid stenosis using high-resolution sonography, 239 (6.1%) of whom were identified as having significant carotid stenosis.

A total of 76 patients (1.8%) had a clinically definitive stroke following surgery. Of those, 18 patients had significant carotid stenosis (23.7%). Although stroke was more common in individuals with carotid stenosis than in those without (7.5% vs 1.8%), 14 of the 18 strokes “occurred outside the territory of diseased carotid artery,” the study authors noted. Furthermore, the majority (76.3%) of postoperative strokes occurred in individuals without carotid disease, and 60% of the strokes were not confined to a single carotid artery.

“According to clinical data, in 94.7% of patients, stroke occurred without direct correlation to significant carotid stenosis,” the study authors wrote. “This study strongly suggests there is no direct causal relationship between postoperative stroke and severe carotid stenosis.”

In a related editorial, Louis R. Caplan, MD, Professor of Neurology at Harvard Medical School in Boston, commented on the neurologic complications of elective coronary artery surgery. “Processes that include checklists and time-outs during which the team reviews findings and strategies have led to reduced medical errors and improved outcomes,” Dr. Caplan wrote. “I suggest that patients and preoperative information should be reviewed before surgery by a team approach that includes a cardiologist who will observe the patients throughout their hospitalization and the cardiac surgeon who will perform the operation.”
Li Y, Walicki D, Mathiesen C, et al. Strokes after cardiac surgery and relationship to carotid stenosis. Arch Neurol. 2009;66(9):1091-1096.
Caplan LR. Translating what is known about neurological complications of coronary artery bypass graft surgery into action. Arch Neurol. 2009;66(9):1062-1064.

CT Scans in Children With Head Injury
Researchers have identified guidelines for accurately predicting children at very low risk of clinically important traumatic brain injuries (TBI), for whom CT scans should be avoided, as reported in the September 15 online Lancet. Nathan Kuppermann, MD, of the University of California-Davis School of Medicine in Sacramento, and colleagues analyzed 42,412 children with head trauma in 25 North American emergency departments, and derived and validated age-specific prediction rules for clinically important TBI. Application of these rules, the investigators believe, could limit CT use, protecting children from unnecessary radiation risks.

Dr. Kuppermann’s group, the Pediatric Emergency Care Applied Research Network, identified the following algorithms with 100% and 99.95% negative predictive value for clinically important TBI, respectively:

• For children younger than 2, normal mental status, no scalp hematoma except frontal, no loss of consciousness or loss of consciousness for less than 5 seconds, nonsevere injury mechanism, no palpable skull fracture, and acting normally according to the parents.
• For children 2 and older, normal mental status, no loss of consciousness, no vomiting, nonsevere injury mechanism, no signs of basilar skull fracture, and no severe headache.

“Data to guide clinical decision making for children with head trauma are urgently needed because head trauma is common and CT use is increasing,” the study authors commented. “Children sustaining minor head trauma infrequently have TBI and rarely need neurosurgery. The small risk of clinically important TBI should be balanced against the risks of ionizing radiation of CTs.”

“Kuppermann and colleagues remind us that the rules are meant to inform clinical decision making, not to replace it,” Patricia C. Parkin, MD, and Jonathon L. Maguire, MD, of the Division of Pediatric Medicine and the Pediatric Outcomes Research Team at the Hospital for Sick Children in Toronto, wrote in an accompanying comment. “The next challenge for evidence-based medicine is knowledge translation. Decision aids might provide structured presentations of options and outcomes.”
Kuppermann N, Holmes JF, Dayan PS, et al. Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study. Lancet. 2009 Sep 14; [Epub ahead of print].
Parkin PC, Maguire JL. Clinically important head injuries after head trauma in children. Lancet. 2009 Sep 14; [Epub ahead of print].

Parent-of-Origin Effects in MS
The greater female-to-male ratio in patients with multiple sclerosis (MS) appears to be more strongly related to the mother, a study published in the August 25 Neurology reported. This maternal parent-of-origin effect, previously seen in studies of half-siblings and avuncular pairs, was found in offspring from a Caucasian mother and North American Aboriginal father.

S.V. Ramagopalan, DPhil, of the Wellcome Trust Centre for Human Genetics at the University of Oxford, UK, and colleagues examined 30,000 MS cases from the Canadian Collaborative Project on Genetic Susceptibility to Multiple Sclerosis (CCPGSMS) and identified 58 individuals with one Caucasian parent and one North American Aboriginal parent. Of these, 27 had a Caucasian mother and 31 had a North American Aboriginal mother. Although the total number of affected offspring was similar in the two mating types studied, the sex ratio differed. Female-to-male sex ratio was 7:1 for patients with MS who had a Caucasian mother, compared with a 2:1 ratio for those with a Caucasian father.

“A parent-of-origin effect (maternal) has been repeatedly observed in MS, based on studies of half-siblings, sibships including dizygotic twins, a large extended Dutch pedigree, and avuncular pairs, as well as timing of birth effect,” the study authors noted. “The comparison of offspring from interracial matings is a novel method of analysis to look for parent of origin effects.

“The data from this study hint at an intriguing possibility that the observed female preponderance of MS could result from environmental factors acting upon mothers to differentially affect MS risk more in female than in male offspring,” the researchers pointed out.

In a related editorial, John W. Rose, MD, commented that this study “illustrated the continued potential of the CCPGSMS to address interesting questions related to the disease.… By evaluating a small set of MS patients with a Caucasian parent and a Native Aboriginal American parent, the investigators were able to assess parental effects on the disease,” he continued. “The susceptibility to disease is presumed to be predominantly introduced by the Caucasian parent based on previous investigations. In this admixture study, the results demonstrate a maternal effect which strongly influences the sex ratio of offspring affected by MS, linking these two classes of gender differences in MS.”
Ramagopalan SV, Yee IM, Dyment DA, et al. Parent-of-origin effect in multiple sclerosis: observations from interracial matings. Neurology. 2009;73(8):602-605.
Rose JW. Multiple sclerosis: evidence of maternal effects and an increasing incidence in women. Neurology. 2009;73(8):578-579.