Biomedical subjects
Bernard S Chang
Publications and source records attributed to Bernard S Chang.
Practice parameter: antiepileptic drug prophylaxis in severe traumatic brain injury: report of the Quality Standards Subcommittee of the American Academy of Neurology.
OBJECTIVE: To review the evidence regarding antiepileptic drug (AED) prophylaxis in patients with severe traumatic brain injury (TBI) in order to make practice recommendations. METHODS: The authors identified relevant studies by searching multiple databases and reviewing reference lists of other sources. They included studies that prospectively compared post-traumatic seizure rates in patients given AED prophylaxis vs controls. Each study was graded (class I to IV) according to a standard classification-of-evidence scheme and results were analyzed and pooled. RESULTS: Pooled class I studies demonstrated a significantly lower risk of early post-traumatic seizures (those occurring within 7 days after injury) in patients given phenytoin prophylaxis compared to controls (relative risk 0.37, 95% CI 0.18 to 0.74). Pooled class I and class II studies demonstrated no significant difference in the risk of late post-traumatic seizures (those occurring beyond 7 days after injury) in patients given AED prophylaxis compared to controls (relative risk 1.05, 95% CI 0.82 to 1.35). Serum AED levels were suboptimal in these studies and adverse effects were mild but frequent. CONCLUSIONS: For adult patients with severe TBI, prophylaxis with phenytoin is effective in decreasing the risk of early post-traumatic seizures. AED prophylaxis is probably not effective in decreasing the risk of late post-traumatic seizures. Further studies addressing milder forms of TBI, the use of newer AEDs, the utility of EEG, and the applicability of these findings to children are recommended.
Bilateral frontoparietal polymicrogyria: clinical and radiological features in 10 families with linkage to chromosome 16.
Polymicrogyria is a common malformation of cortical development characterized by an excessive number of small gyri and abnormal cortical lamination. Multiple syndromes of region-specific bilateral symmetric polymicrogyria have been reported. We previously have described two families with bilateral frontoparietal polymicrogyria (BFPP), an autosomal recessive syndrome that we mapped to a locus on chromosome 16q12-21. Here, we extend our observations to include 19 patients from 10 kindreds, all linked to the chromosome 16q locus, allowing us to define the clinical and radiological features of BFPP in detail. The syndrome is characterized by global developmental delay of at least moderate severity, seizures, dysconjugate gaze, and bilateral pyramidal and cerebellar signs. Magnetic resonance imaging demonstrated symmetric polymicrogyria affecting the frontoparietal regions most severely, as well as ventriculomegaly, bilateral white matter signal changes, and small brainstem and cerebellar structures. We have refined our genetic mapping and describe two apparent founder haplotypes, one of which is present in two families with BFPP and associated microcephaly. Because 11 of our patients initially were classified as having other malformations, the syndrome of BFPP appears to be more common than previously recognized and may be frequently misdiagnosed.
Mapping form and function in the human brain: the emerging field of functional neuroimaging in cortical malformations.
Malformations of cortical development (MCDs) are increasingly being recognized as a common cause of epilepsy in cases previously felt to be cryptogenic. MCDs occur when the normal process of cerebral cortical development is disrupted, and include disorders of neuronal proliferation, migration, and organization. Many have a genetic basis and the genes responsible for some MCDs have been identified. MCDs represent a unique and valuable substrate in functional brain mapping studies, since as developmental lesions they provide complementary information to studies performed on patients with acquired brain lesions. In recent years an increasing number of functional neuroimaging methods, including positron emission tomography, single photon emission computed tomography, magnetic resonance spectroscopy, and functional magnetic resonance imaging, have been applied to patients with MCDs. In this review we highlight some of the prominent findings in this emerging field by presenting the functional neuroimaging characteristics of selected MCDs.
Outpatient EEG monitoring in the presurgical evaluation of patients with refractory temporal lobe epilepsy.
Most epilepsy centers obtain ictal EEG recordings to localize the epileptogenic zone during presurgical evaluations. Inpatient monitoring is standard practice but is expensive and can be inconvenient. The authors sought to determine whether outpatient monitoring can be safe and effective as the sole method of recording seizures in the presurgical evaluation of patients with refractory temporal lobe epilepsy. They reviewed the data of seven temporal lobectomy patients whose presurgical monitoring was performed entirely outside the hospital. Mean baseline seizure frequency was at least 9.1 seizures per week. An average of 7.4 seizures was recorded over 9.4 days of monitoring. Only one patient had any antiepileptic drug taper; none suffered any complications. After temporal lobectomy on the side of demonstrated ictal onset, postoperative follow-up averaged 5.5 years. At the most recent follow-up, all patients were either seizure free or had only rare disabling or nocturnal seizures (four patients had outcomes in Engel's class I and three patients in Engel's class II). A comparison group who underwent standard inpatient monitoring was similar in average seizure frequency, monitoring duration, number of seizures recorded, and postoperative outcome, although all but one had antiepileptic drugs tapered during monitoring. The authors conclude that there is a subset of patients for whom solely outpatient presurgical EEG monitoring can be used to help plan successful temporal lobectomy.