Abstracts

Magnetoencephalography (MEG) has been used as a diagnostic tool for children with intractable localization-related epilepsy. The accuracy of the MEG spike source localization onto MRI is dependent upon the ability of the patient to keep still in the dewar. Thus, uncooperative children require general anesthesia (GA) for MEG and MRI studies. The purpose of the paper is to evaluate the quantity of MEG interictal epileptiform discharges, comparing those of EEG between lesional and non-lesional cases.,
Forty-Six patients with intractable epilepsies underwent MEG recordings under GA from March 2001 to April 2006. We analyzed MEG dipoles, and compared epileptiform discharges among MEG, simultaneous EEG and separate scalp video EEG (VEEG) in 33 patients (20 boys; 13 girls) who underwent prolonged VEEG before the MEG study. The age ranged from 3 to 14 years with a mean of 6.8 years. Twenty patients had MRI lesion. MEG was performed with whole-head 151-channel gradiometers (VSM MedTech Ltd., Port Coquitlam, BC, Canada). Sampling rate was 625 Hz. We recorded 15 to 20 data sets of 2-minute periods. Propofol and remifentanyl were used for GA.,
Nineteen (95%) of 20 patients with lesions showed intermittent or frequent spikes on VEEG (6 focal cortical dysplasia, 3 tuberous sclerosis, polencephalic cyst, parieto-occipital atrophic brain, heterotopia, splenial demyelination, glioma, Rasmussen[apos]s encephalitis periventroclar heterotopia, Sturge-Weber syndrome, thickened gyri, mesial temporal sclerosis, entire brain atrophy, one each ). Seventeen (89 %) of the19 patients had intermittent epileptiform discharges on MEG and EEG under GA, and the other two (11 %) patients (splenial demyelination and glioma) had no epileptiform discharges. In one patient with residual seizures, after hemispherectomy for hemimegarencephaly, VEEG showed neither electroclinical seizures nor interictal discharges, and MEG did not show any epileptiform discharges.,
Pediatric patients with intractable lesional epilepsy can be succeeded to study MEG under GA to record the epileptiform discharges and localize the dipoles for delineating the epileptogenic zone. In patients with intractable non-lesional epilepsy, when VEEG shows intermittent or frequent spikes and lateralized seizure semiology, MEG may show the epileptiform discharges to identify the epileptogenic hemisphere.,