Abstracts

Rationale: Sturge-Weber syndrome (SWS) is a congenital neurocutaneous disorder characterized by port-wine nevus, glaucoma, and leptomeningeal angioma in the brain. Almost half of patients with SWS have epilepsy, and some require surgery for epilepsy. However, seizures in these patients have never been characterized. In this study, we analyzed interictal and ictal discharges from intracranial subdural electroencephalography (EEG) recordings of five patients with SWS to elucidate epileptogenicity in this disorder.Methods: The patients’ ages ranged from 1 to 9, and all five had intractable seizure and mental retardation. After each subject submitted to a non-invasive diagnostic protocol for epilepsy, we implanted subdural electrodes over the leptomeningeal angiomas. A blinded investigator evaluated interictal and ictal discharges by visual inspection. We examined the following seizure parameters: seizure onset zone (SOZ), propagation speed, duration, and frequency analysis at seizure onset.Results: We recorded 21 seizures that initiated from the cortex under the leptomeningeal angioma; they usually presented as motionless staring and respiratory distress. The average seizure propagation speed and duration were 3.1 ± 3.6 cm/min and 17 ± 29 min, respectively. Significant differences between SOZ and non-SOZ were detected from 15s before seizure onset in 10-30Hz, from 5s before seizure onset in 30-50Hz and from 3s before seizure onset in 50-80Hz.Conclusions: The ECoG analysis shows that, seizure propagation in SWS is relatively slow and seizure duration is relatively long. Low gamma activity was detected before seizure discharges began. Our results suggest that epileptogenicity in SWS may be due to ischemia.