ID 399 – Investigation of patients with hippocampal sclerosis associated with unusual epileptic foci

Rationale Hippocampal sclerosis (HS) is usually associated with anterior temporal spikes/sharp waves in EEG. We aimed to investigate the differences between HS patients with unusual epileptic foci in comparison to typical foci. Methods 126 patients followed up with HS were evaluated. All MRIs were investigated for the presence of two major criteria of HS diagnosis, namely T1 atrophy and T2 hyperintensity. All EEG and video-EEG investigations (a total of 496) were re-evaluated for unusual epileptic activities except T1/2, F7/8, T3/4 foci. Post-operative seizure outcomes were investigated according to the Engel classification. Results There were 20 patients (9 males; 7 with bilateral HS) with unusual foci with a follow-up duration of 107.8 ± 89.3 months. Their findings were compared to 106 patients with usual HS. Statistical analysis could not show any difference between these groups. All but 2 showed drug-resistant course; 5 had status epilepticus and 5 had mental retardation without reaching statistical significance. Ten were operated and 7 of them were grouped as Engel classification 1. Conclusion Our study showed that unusual epileptic foci could be seen in 15.9% of HS patients. Although they had drug resistant course, they might show good post-operative outcome, when preoperative diagnostics were appropriately planned.