Abstracts

Rationale: Porencephalic cyst is a brain lesion caused by early ischemic insult or hemorrhage. We evaluated magnetoencephalography (MEG) spike source to localize the epileptogenic zone in children with intractable epilepsy secondary to porencephalic cyst. Methods: We retrospectively studied 14 children with intractable epilepsy secondary to porencephalic cyst (6 girls; 8 boys; age range 2-19 years at MEG), who underwent prolonged scalp video-EEG, MRI and MEG. Interictal MEG spike source (MEGSS) locations were compared to ictal and interictal zone from scalp video-EEG. Results: MRI showed porencephalic cysts in extratemporal lobes in 7 patients, within temporal lobe in 5, extending temporal region in 2. MEGSSs were clustered in the margin of the porencephalic cyst in all 14 patients. One single cluster of MEGSSs was seen in 13 patients, two clusters in 1 patient. Ictal EEG discharges were lateralized and concordant to MEGSS hemisphere in 9 patients (64%). Ictal EEG discharges were localized in one lobe in 1 patient, 2 lobes in 4, and diffuse hemisphere in 4. The other 5 patients showed generalized or diffusely undetermined ictal EEG discharges. Interictal EEG discharges were lateralized in 9 (64%) patients consisting of one lobe in 2 patients, two lobes in 2 patients, and diffuse hemisphere in 5 patients. Five patients had resective surgery. Two patients underwent lesionectomy plus MEGSS clusterectomy. One patient had resection after intracranial video EEG and one patient had first lesionectomy plus MEGSS clusterectomy and few years later, resection following intracranial video EEG. Temporal lobectomy and amygdalalohippocampectomy was performed in one patient. All of them achieved seizure freedom following surgery. Conclusions: Scalp video EEG had a difficulty of lateralizing and localizing their interictal and ictal epileptiform discharges correlating with porencephalic cysts. MEG accurately delineated single or multiple marginal epileptogenicity surrounding porencephalic cysts in children with intractable epilepsy. Complete resection of MEGSSs clustered aside of porencephalic cysts can provide favorable seizure outcomes.