Abstracts

Rationale: Neocortical epilepsy (NE) surgery is widely performed for severely intractable seizure disorders localized to lateral temporal and extratemporal locations. These surgeries require highly specialized costly evaluations, and nearly always require intracranial EEG (ICEEG) recordings. The American Academy of Neurology Practice Parameter Statement published in 2003 states that insufficient evidence exists to make a recommendation as to whether patients will or will not benefit from NE surgery. This work provides an estimate of long-term seizure-free outcome data specific to this very important subset of epilepsy surgery patients, and can be used in decision analysis of the clinical utility of NE surgery. Methods: A retrospective review of all ICEEG based NE resections since 1996 at UAB was performed. An epilepsy nurse specialist (SM) obtained Engel class outcome assessments from telephone call interview or medical record review (when patients could not be reached). Outcomes were stratified according to MRI classification negative (normal or questionable abnormality) and positive (localized, multiple, large or ambiguous abnormality). Results: Of 115 NE patients that had ICEEG investigations at UAB since January 1996, 99 (86%) had surgical resections. Seventy-four patients (one lost to follow up) had one year or greater duration of follow up. The Table shows demographics, epilepsy class and post surgery outcome of these cases sorted by MRI negative (n=35) and MRI postive (n=39) classification. The independent variables were comparable between groups. The mean duration of follow up for assessment of seizure outcome was 4.8 years (range 1.3-13.8). The overall seizure free incidence (57% MRI negative and 54% MRI positive) was not significantly different between groups. Conclusions: ICEEG based NE epilepsy surgery seizure-free outcomes for normal MRI cases are similar to those with abnormal MRI. Although predictors of outcome in NE remain unclear, overall effect on seizure-free outcome is robust. These data and others reported in the literature can be combined with cost and risk assessments in decision-making models to perform sensitivity analyses of all variables effecting whether patients should have NE surgery.