Abstracts

RATIONALE: To analyze the value of magnetoencephalography (MEG) in patients with seizures of opercular origin in comparison to other noninvasive studies.
METHODS: A review of all surgical cases completed at Henry Ford Hospital since 1993 was performed to identify patients with seizures of presumed opercular origin. Patients who had completed intracranial implantation with recording of typical ictal events, a MEG study, and subsequent focal resection were included. Data obtained from MEG was compared to localizing data obtained from MRI, interictal / ictal SPECT, and scalp EEG (interictal and ictal).
RESULTS: Two patients were identified (ages 7, 39) with intracranial interictal / ictal patterns suggesting opercular onset (Patient 1, right frontoparietal; Patient 2, left parietal). Both patients were seizure-free at the last follow-up visit (3 months , and 5 years). Noninvasive studies revealed normal MRI, and nonlocalizing interictal SPECT in both patients. Ictal SPECT was only completed in Patient 1, but no significant asymmetry in perfusion was evident. Interictal EEG revealed generalized 1.5-2.5 Hz spike and slow waves, independent right [gt] left temporal spikes, right frontotemporal slow waves, occasional SP1, F4, and F8 sharps, and right temporal PPDA (Patient 1); rare T3 sharps (Patient 2). Ictal EEG pattern consisted of a 1.5 - 2.5 Hz generalized spike and slow waves with an initial lead in consistently recorded over the right frontotemporal region in Patient 1. No discernible ictal pattern was evident with recorded seizures in Patient 2. MEG studies revealed high-amplitude discharges localizing to a large area of the right hemisphere with greatest density in the frontoparietal operculum (Patient 1), and a strong concentration of discharges emanating from the posterior left perisylvian region (Patient 2).
CONCLUSIONS: Magnetoencephalography may provide key localizing data compared to other noninvasive studies in the presurgical evaluation of patients with partial epilepsy of opercular origin.