Abstracts

Rationale: Epilepsy surgery is an important clinical option for individuals with medically intractable epilepsy, yet referral for evaluation typically takes 20 years from epilepsy diagnosis. Many barriers to epilepsy surgery have been identified. Aim of this study was to describe the demographics of individuals referred for epilepsy surgery evaluation and treatment in a community-based epilepsy program. Methods: Among 480 patients referred to the author s epilepsy clinic for intractable epilepsy over two years time (2008-10), 11 patients, aged 16-73 yrs (mean age 32yrs), were evaluated and treated for epilepsy surgery. 60% of all referrals came from non-neurologists, while all epilepsy surgery candidates came from neurologists. All 11 (2.2%) had medically intractable epilepsy confirmed by video-EEG monitoring. The presurgical evaluation also included clinical evaluation, MRI, ictal and interictal SPECT, Wada testing, neuropsychological evaluation, as well as surgical consultation. The duration of epilepsy was 12 yrs (range 1-30yrs). Four of the patients had presurgical diagnoses of symptomatic epilepsy (2 lesional, 2 mesial temporal lobe sclerosis). All proceeded to focused intracranial monitoring with subdural strips. Localization to the right mesial temporal lobe (3/11) and lesions (2/11) lead to resection. Initial intracranial monitoring lateralized to a frontal seizure focus in over half of the cases (6/11), leading to subdural grid localization and cortical mapping. A single frontal seizure focus was identified in 5/6 patients [2 left, 3 right hemisphere], resulting in combined focal cortical resection and multiple subpial transections. The 6th patient had 2 independent seizure foci in the right mesial temporal and right frontal lobes. Results: Neuropathology review of all resections identified focal cortical dysplasia (CD) in 5/6 frontal cases [5 Type I & 1 Type IIa CD] (45% all cases). Ectopic neurons were identified in the single case with 2 seizure foci. Hippocampal sclerosis in all 4 mesial temporal lobe resections patients, only 2 of whom had neuroimaging correlate on MRI. The two lesional cases were low grade gliomas. Clinical follow up of the 11 patients undergoing epilepsy surgery range from 2 yrs to 4 mo (mean 11 mo). Baseline seizure frequency was an average of 4/month (range 2-6). Nine patients (81%) had Engel Class1 outcome, including no auras. The single patient with CD Type IIa had rare sleep-onset seizures, stopped with initiation of a third antiepileptic drug (AED). One of the two patients with low grade glioma had transient break-through seizures after initial early attempt to lower AED dosing. A single significant complication included a subdural hematoma associated with a grid, with no morbidity. Conclusions: In a small case series, extratemporal/ frontal lobe epilepsy represented a majority of cases referred for clinical evaluation in a community-based program. All surgical cases had abnormal neuropathology findings, with CD representing the common finding. A combination of multiple subpial transections and focal cortical resections was effective in initial follow up.