Abstracts

Ictal EEG patterns characteristic of temporal lobe seizures have been defined for the adult population (Risinger et al. Neurology 39:1288.). Many adult epilepsy centers use this pattern as a factor in considering the approach to surgical candidates. The applicability of this finding to the pediatric population has not been explicitly addressed. The ictal EEG morphology in pediatric surgical patients with hippocampal sclerosis (HS) has been characterized in terms of rhythmic versus arrhythmic patterns (Mohamed et al. Neurology 56:1643). We report on the ictal and interictal EEG patterns in a series of pediatric epilepsy surgery patients with isolated evidence of mesial temporal sclerosis (MTS), based on MRI and surgical findings., We retrospectively reviewed the ictal and interictal EEG patterns in eight pediatric (age of surgery 4-14 years) patients who underwent surgery for refractory partial epilepsy and unilateral MTS, without evidence of dual pathology on MRI. The age at seizure onset ranged from 7 months to 11 years. During long-term video/EEG monitoring with scalp electrodes, each patient demonstrated partial seizures that originated in the temporal lobe ipsilateral to the MRI abnormality., All of the patients demonstrated a focal temporal ictal pattern of 5 Hz or faster. This pattern appeared as the first ictal electrographic change apart from diffuse attenuation/suppression, or as a delayed pattern that followed regional electrographic changes, as previously described. Surgical pathology documented HS in 7 of the 8 patients. The remaining patient had only gliotic changes in the hippocampus without documented neuronal loss. None had evidence of dual pathology. All achieved seizure freedom (follow-up 3m-2.5y).
Only two patients (ages 11 and 14) had interictal spike-waves restricted to the anterior temporal region. One had no interictal spikes. Interictal discharges in the other patients occurred over the anterior-, mid- and posterior-temporal, central, and occipital electrodes. This is in contrast to adult and adolescent patients with MTS where surface interictal discharges are typically restricted to the anterior temporal regions., This series suggests the surface ictal EEG pattern of temporal rhythms of [gt]5 Hz may apply to pediatric patients with MRI evidence of MTS. This has important implications as a potential selection tool in choosing pediatric epilepsy surgery candidates, especially when MRI and ictal EEG data show coherence while interictal EEG spike-wave locations vary.,