Abstract
ObjectiveAlmost two-thirds of patients with Sturge-Weber syndrome (SWS) have epilepsy, and half of them require surgery for it. However, it is well known that scalp electroencephalography (EEG) does not demonstrate unequivocal epileptic discharges in patients with SWS. Therefore, we analyzed interictal and ictal discharges from intracranial subdural EEG recordings in patients treated surgically for SWS to elucidate epileptogenicity in this disorder.MethodsFive intractable epileptic patients with SWS who were implanted with subdural electrodes for presurgical evaluation were enrolled in this study. We examined the following seizure parameters: seizure onset zone (SOZ), propagation speed of seizure discharges, and seizure duration by visual inspection. Additionally, power spectrogram analysis on some frequency bands at SOZ was performed from 60 s before the visually detected seizure onset using the EEG Complex Demodulation Method (CDM).ResultsWe obtained 21 seizures from five patients for evaluation, and all seizures initiated from the cortex under the leptomeningeal angioma. Most of the patients presented with motionless staring and respiratory distress as seizure symptoms. The average seizure propagation speed and duration were 3.1 ± 3.6 cm/min and 19.4 ± 33.6 min, respectively. Significant power spectrogram changes at the SOZ were detected at 10–30 Hz from 15 s before seizure onset, and at 30–80 Hz from 5 s before seizure onset.SignificanceIn patients with SWS, seizures initiate from the cortex under the leptomeningeal angioma, and seizure propagation is slow and persists for a longer period. CDM indicated beta to low gamma-ranged seizure discharges starting from shortly before the visually detected seizure onset. Our ECoG findings indicate that ischemia is a principal mechanism underlying ictogenesis and epileptogenesis in SWS.
Highlights
Sturge-Weber syndrome (SWS) is a congenital neurocutaneous disorder characterized by facial cutaneous nevus flammeus, leptomeningeal angioma, and glaucoma [1]
We obtained 21 seizures from five patients for evaluation, and all seizures initiated from the cortex under the leptomeningeal angioma
Significant power spectrogram changes at the seizure onset zone (SOZ) were detected at 10–30 Hz from 15 s before seizure onset, and at 30–80 Hz from 5 s before seizure onset
Summary
Sturge-Weber syndrome (SWS) is a congenital neurocutaneous disorder characterized by facial cutaneous nevus flammeus, leptomeningeal angioma, and glaucoma [1]. Clinical problems particular to neurology are migraine, hemiparesis, seizures, and mental retardation [2]. Maintenance of psychomotor development is the crucial therapeutic goal, and this requires prompt seizure control [3]. Seizures affect 75–90% of patients with SWS, and 50–60% cases are refractory to medical treatment [4,5]. Surgical interventions need to be considered for SWS patients with drug-resistant epilepsy. Scalp electroencephalography (EEG) does not provide definitive information to determine the severity of epilepsy and the origin and propagation of epileptic discharges [6,7,8]. The mechanisms of ictogenesis and epileptogenesis in SWS have not been clarified. To properly evaluate the severity and EEG findings, we have to understand the mechanism of epilepsy in SWS
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