Abstracts

Rationale: Hippocampal sclerosis is a major risk factor for seizure intractability in patients with temporal lobe epilepsy. However, other mesiotemporal lesions like cavernomas are also associated with a higher risk of intractability as compared to patients with extra-mesiotemporal lesions. The aim of the present study was to evaluate differences in seizure control as well as seizure semiology in patients with the syndrome of mesial temporal lobe epilepsy (MTLE) caused by either hippocampal sclerosis or cavernomas. Methods: Drug resistance and seizure freedom after epilepsy surgery were compared in eleven patients with MTLE due to mesiotemporal cavernomas and 33 patients with hippocampal sclerosis using the Mann-Whitney test. Other parameters like seizure semiology, seizure frequency, initial precipitating events and risk factors for epilepsy as well as psychiatric comorbidity were evaluated in an exploratory analysis using χ² and Mann-Whitney tests. Results: Patients with MTLE caused by cavernomas suffered less often from drug resistance (P=0.003) and tended to be more often seizure free after epilepsy surgery (P=0.036) as compared to patients with HS. The exploratory analysis revealed a somewhat lower percentage of patients with cavernomas to present with aura, especially epigastric aura (P=0.049) and complex partial seizures (P=0.086). Seizure frequency tended to be lower in the cavernoma group (mean seizure frequency 466 per year vs. 211 per year, P=0.057) and a history of an initial precipitating event was less frequent (P=0.034). The other parameters did not show relevant differences between patients with HS and mesiotemporal cavernomas. Conclusions: The results suggest that patients with MTLE caused by mesiotemporal cavernomas are less likely to suffer from drug resistant epilepsy as compared to patients with MTLE caused by HS. Additionally, they tend to show a more favourable postoperative outcome and a lower seizure frequency. This information is important for counselling patients regarding their risk of seizure intractability and their chance to be seizure free after epilepsy surgery.