Investigation of Patients with Hippocampal Sclerosis Associated with Unusual Epileptic Activities

Ebru Nur Vanlı Yavuz; Hakan Yener; Zeynep Aydın Özemir; Nerses Bebek; Candan Gürses; Ayşen Gökyiğit; Betül Baykan

doi:10.4274/tnd.80037

Ebru Nur Vanlı Yavuz, Hakan Yener, Zeynep Aydın Özemir, Nerses Bebek, Candan Gürses, Ayşen Gökyiğit, Betül Baykan

İstanbul University İstanbul Faculty of Medicine, Department of Neurology, Division of Clinical Neurophysiology, İstanbul, Turkey

Keywords: Mesial temporal lobe epilepsy, hippocampal sclerosis, electroencephalography, prognosis

Abstract

INTRODUCTION: Hippocampal sclerosis (HS) is usually associated with typical anterior temporal spikes/sharp waves in the electroencephalography (EEG). We aimed to investigate the clinical, electrophysiologic differences, and prognosis between HS patients with unusual epileptic foci in comparison with patients with typical foci.

METHODS: Patients diagnosed who were diagnosed as having mesial temporal lobe epilepsy with HS in our center were included. All magnetic resonance imaging (MRI) results 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. Clinical and other laboratory data were retrospectively reevaluated by two investigators and the groups with usual and unusual epileptic activities for this syndrome were statistically compared.

RESULTS: A total of 124 patients including 20 (16.1%) with unusual epileptic activities (group 1) and 104 patients with typical foci (group 2) were evaluated. We observed 11 posterior temporal (T5/T6), four frontal (F3/F4), four frontopolar (Fp1/2), two occipital (O1/O2), three central (CP/FC) unusual foci, and two generalized epileptiform discharges in these 20 patients. Impaired background activity, nonspecific interictal diffuse slowing, and atypical seizure offset patterns were more frequently observed in group 1. Forty-nine patients underwent surgery after appropriate preoperative diagnostics; there was no significant difference in the postoperative outcome between the groups despite a tendency to better prognosis in group 2.

DISCUSSION AND CONCLUSION: Our study showed that unusual epileptic foci could be seen in 16.1% of patients with HS. Although some patients with HS have these atypical interictal EEG findings, they might obtain good post-operative outcomes when preoperative diagnostics are appropriately planned.