Investigation of Patients with Hippocampal Sclerosis Associated with Unusual Epileptic Activities

Abstract

Objective: 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. Materials and 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. 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. Keywords: Mesial temporal lobe epilepsy, hippocampal sclerosis, electroencephalography, prognosisAmaç: Hipokampal skleroz (HS) genelde elektroensefalografide (EEG) ön temporal elektrotlarda görülen tipik dikenler/keskin dalgalar ile ilişkilidir. Çalışmada bu odaklardan farklı lokalizasyonlarda epileptik odakların ve aktivitelerin görüldüğü olguların, tipik odakları olanlara kıyasla klinik, elektrofizyolojik özelliklerinin ve prognoz farklarının araştırılması amaçlanmıştır. Gereç ve Yöntem:Merkezimizde mezyal temporal lob epilepsisi ile giden HS tanısıyla takipli olgular çalışmaya dahil edildi. Tüm manyetik rezonans görüntülemeler (MRG) iki ana HS tanı kriterinin (hipokampal yapılarda atrofi ve T2 ya da FLAIR sekanslarında sinyal artışı) varlığı açısından incelendi. Tüm EEG ve video EEG incelemeleri (toplam 496 adet) T1/2, F7/8, T3/4 odakları dışında farklı bir alanda epileptik aktivitesi olan ve olmayan hastalar açısından incelendi. Klinik ve diğer laboratuvar incelemeleri iki araştırmacı tarafından retrospektif olarak değerlendirildi. Olağan dışı odağı olan hastalarla olağan d...