Abstracts

Rationale: Focal cortical dysplasias (FCDs) have been recognized as the second most frequent underlying pathology in refractory epilepsy. Post surgical seizure free rates range from 45.3% to 76%. The aim of this study was to evaluate long-term seizure outcome following epilepsy surgery at our institution in patients with refractory epilepsy due to FCDs as confirmed by pathology of the resected tissue.Methods: Following IRB approval, we searched the Henry Ford electronic database to identify patients older than 18 who had epilepsy surgery, long-term post surgical outcome in our institution and histopathological diagnosis of focal cortical dysplasia. Engel’s classification was used to classify outcome at the most recent follow-up (class I=no seizures, class II=rare disabling seizures, class III=worthwhile improvement and class IV =no improvement). We collected patient demographics, age at epilepsy onset and surgery, MRI, video scalp or invasive EEG monitoring localization, SPECT, Magnetoencephalography (MEG) data and number of antiepileptic drugs (AEDs) before and after surgery. Descriptive statistics were applied.Results: Eighteen patients (10 females) with a mean age of 40.3±12.5 years and mean follow up of 79.8±56.5 months were included in the study. Mean age at epilepsy onset was 8.06±5.1 years and at epilepsy surgery 31.67±10.8 years. Two patients had already had a history of previous surgery. MRI showed findings consistent with FCD in 7 patients (38.8%). Invasive video EEG monitoring was performed in 15 patients (83%) due to inconclusive findings from non-invasive procedures. MEG was performed in 7 patients (39%) for further localization, and in one of them invasive monitoring was avoided. Surgery site and location of FCD was temporal in 9 patients, extratemporal in 4 and multilobar in 5. Postoperative outcome was Engel class I in 13 patients (72.2%), class II in 4 patients (22.2%) and class IV in 1 patient (5.5%). Of the seizure free patients, one achieved seizure freedom in 1 year after surgery, 1 in 7 years, 2 in 8 years and another one in 13 years. The mean number of AEDs before surgery was 2±0.76 (range 1-3) and after 1.72±0.9 (range 0-3). Following surgery 55% of patients were on the same number of AEDs, 33.3% on fewer and in 11.1% one more AED was added. Only one patient achieved long-term seizure freedom off AEDs. Conclusions: Our study showed that epilepsy surgery in FCDs has a favorable outcome and seizure freedom can be achieved in 72% of patients. Despite the small sample size our results are in agreement with a number of studies that have reported similar post surgical outcomes. Interestingly, in some of our patients despite infrequent seizures for a number of years seizure freedom was eventually achieved. A high percentage of our patients (83%) required invasive recordings, highlighting the difficulties in localizing the extent of epileptogenic zone in focal cortical dysplasias. In our patient group the number of AEDs before and after surgery did not differ significantly which suggests that most patients with FCDs should remain on AEDs to maintain seizure freedom.