gms | German Medical Science

Objective: The most common type of pharmacoresistant epilepsy is temporal lobe epilepsy which can be treated surgically by anterior mesial temporal lobe resection (AMTLR). One of the neuropathological findings is focal cortical dysplasia type IIIa (FCD IIIa) which is a developmental lesion caused by problems in neuronal formation and migration in the temporal pole combined with hippocampal sclerosis (HS). Here we investigate the impact of FCD IIIa on patients operated on a temporal lobe epilepsy by AMTLR.

Method: We performed a retrospective analysis of patients who received an AMTLR at our institution between June 2011 and October 2013. The patients were analysed regarding the presence of an FCD type IIIa or solely a hippocampal sclerosis. The groups were compared by means of age, gender, years of epilepsy and seizure outcome using the Engel classification.

Results: Thirty-nine patients suffering for temporal lobe epilepsy were operated on using an AMTLR at our institution between June 2011 and October 2013. FCD type IIIa was diagnosed in 11 cases. Of those 7 were female and 4 male. Mean seizure duration was 31.1 years. Four patients were initially treated by selective amygdalohippocampectomy and had to be reoperated due to ongoing seizures. Mean follow-up was 9 months. All patients with diagnosed FCD type IIIa showed a favorable seizure outcome (Engel class I-II), whereas 29% of the patients with no pathological findings in the temporal pole had an unfavorable outcome (p<0.001).

Conclusions: Patients with a FCD type IIIa had a significantly better seizure outcome after AMTLR compared to patients with solely hippocampal sclerosis. This emphasizes the hypothesis that AMTLR might be superior to selective amygdalohippocampectomy in terms of seizure control as FCD type IIIa are often underdiagnosed. Thus, further effort should be undertaken with regard to presurgical diagnostic tools to become able to diagnose FCD type IIIa preoperatively for better prediction of seizure outcome.