Abstracts

The purpose of this study is to identify specific ictal electroencephalographic (EEG) patterns associated with temporal lobe epilepsy(TLE) in the pediatric population. The localization of temporal lobe foci (mesial versus neocortical) in adults has been well described. It is important to observe whether any age related maturational changes, or other variables related to the developing brain, have any impact on the ictal scalp EEG recordings. We reviewed the ictal scalp EEG in 9 epilepsy surgery candidates (age 7-17 years). Mean age at seizure onset was 10 years (range 5-16). 7 patients were male. A total of 33 seizures were recorded. The ictal EEG features during the first 40 seconds were included in the analysis. Several patterns were identified. The location of the seizure focus was confirmed in 5 patients, that either became seizure free or only had auras after temporal lobectomy(TL) and with a minimum of 1 year postoperative follow up. The remaining 4 patients either just underwent TL (n=1) or are completing the presurgical evaluation. The seizure semiology in all patients was consistent with TLE seizure semiology. The most common sequence noted consisted of an aura of fear, rising epigastric sensation, followed by loss of consciousness, staring, automatisms such as lip smacking, unilateral dystonic posturing, unilateral or bilateral hand automatisms. All patients had brain MRI lesions that either involved the mesial structures only (n=4), the neocortex (n=2) or both. The abnormalities identified on the imaging studies were suggestive of hippocampal sclerosis (n=3), malformations of cortical development (n=2), dual pathology (n=2), low grade tumor (n=2). The ictal EEG patterns fell into one of the following types: bifronto-central theta to alpha range activities, followed within 10-20 seconds(s) by unilateral temporal theta(UTT) activity; bifrontal delta activity, followed within 10-25 s by UTT rhythm or first by unilateral delta then theta activities; unilateral temporal delta(UTD)activity, followed within 5-15 s by UTT; less commonly, delta intermixed with theta activity from onset to offset. The most common ictal EEG pattern was represented by the UTD activity, followed within 5-15 s by UTT. This is also the most common pattern previously described in adult patients with mesial TLE. 1 patient with bifrontal delta pattern at onset, followed by UTD, then UTT, became seizure free after surgery. 1 patient with bifronto-central theta to alpha range activities, followed by UTT activity, has auras only postoperatively. A larger series of pediatric patients with TLE is needed to further identify the various ictal scalp EEG patterns within this age group, and distinguish any particularities in pediatric versus adult patients with mesial TLE, if any.