Abstracts

Rationale: Interictal epileptiform discharges (IED) had a significant predictive value and may guide epilepsy surgery resection to prevent early unfavorable outcome. Study aim was to determine how specific intracranial EEG (ICEEG) IED could predict epilepsy surgery outcome. Methods: Retrospective study of 281 patients who had epilepsy surgery guided by ICEEG between 2000 and 2008, and had subsequent follow-up in the clinic. Surgical resection of IED types was reviewed to predict epilepsy surgery outcomeResults: : Follow-up duration after surgery range was between 6 months to 11 years (Mean of 3 Years). Epilepsy surgery outcome at the time of follow-up was seizure free (Favorable Outcome) in 141, and seizure reoccurrence (Unfavourable Outcome) was in 140; 36/54 had complete resection of paroxysmal fast, of which 18(50%) had favourable outcome (p=0.622); 58/110 had complete resection of repetitive spikes, of which 28(48%) had favourable outcome (p=0.432); 76/137 had complete resection of runs slow repetitive spikes, of which 42(55%) had favourable outcome (p=0.140); 89/161 had complete resection of isolated spikes, of which 57(64%) had favourable outcome (p < 0.0001). Conclusions: The presence of interictal epileptiform discharges (particularly isolated spikes) during ICEEG recoding beyond the area of resection correlated with unfavourable epilepsy surgery outcome. ICEEG findings (e.g. Interictal epileptiform discharges) potentially may have prognostic significance would need further clarification.