Abstracts

Dysgenesis of the corpus callosum (DCC) is a congenital brain anomaly with a wide spectrum of clinical features which is dependent upon the presence, and extent of associated brain malformations. Epilepsy is one of the most prevalent clinical features of DCC, and can range from mild to severe and intractable. Whether patients with DCC and intractable epilepsy can benefit from epilepsy surgery is not clear. We analyzed the clinical and neuroimaging features, as well as surgical outcome, in six children with DCC and intractable epilepsy who underwent epilepsy surgery in the Children[apos]s Hospital of Michigan. The six children (age range: 5 weeks to 15 years; 5 boys) were identified from our epilepsy surgery database. Investigated clinical data included: maternal and perinatal history, seizure types and age at seizure onset, cranial MRI, glucose metabolism positron emission tomography (PET) imaging and surgical outcome. Maternal history was significant for Gonorrhea, Chlamydia and Toxoplasma infection in one and gestational diabetes and fetal demise in another. All subjects had intractable complex partial seizures with variable age of onset (1.5 hours to 3 years old), but three of the six children had additional seizure types (epileptic spasms in two and myoclonic seizures in one). All children had developmental delay and one had a hemianopsia. MRI in five patients showed associated brain malformations; of these, two had focal cortical dysplasia (one with associated congenital hydrocephalus) and three had hemimegalencephaly. In a single patient, no MRI-defined cortical abnormality was noted. PET scan showed focal glucose hypometabolism in the presumed epileptic hemisphere in four children and unilateral intense hypermetabolism in the other two. Video-EEG showed that three children had a focal ictal onset arising from the hemisphere showing MRI and PET abnormalities. Two children had a generalized onset of ictal discharges with mild lateralization to the presumed epileptic hemisphere based on MRI and PET. The remaining child had multifocal ictal onset with 80% of seizures showing an onset arising from the presumed epileptic hemisphere. Three patients underwent multilobar cortical resection, two had hemispherectomy and one had subtotal hemispherectomy sparing the primary sensorimotor cortex. Five out of the six children became seizure-free after surgery (Follow-up periods: 1 to 2 years), and one of them has been successfully weaned off from anti-epileptic medications. The remaining child had a 50% reduction of seizures. Our data suggest that the outcome of epilepsy surgery in carefully selected children with DCC and intractable epilepsy can be favorable and is dependent upon the location and extent of associated brain malformations. Concordance between the ictal EEG and neuroimaging features is essential in order to achieve a good surgical outcome.