Abstracts

Rationale: Surgical treatment with temporal lobectomy can lead to favorable seizure outcomes in medically-refractory temporal lobe epilepsy (TLE). While most studies focus on seizure-freedom after temporal lobectomy, less is known about seizure semiology in patients who fail surgery. Morbidity differs between seizure types that impair or spare consciousness. Among TLE patients with continued seizures after surgery, how does temporal lobectomy influence seizure type and frequency?Methods: We performed a retrospective cohort study examining patients undergoing temporal lobectomy for epilepsy at our institution from January 1995 to August 2010. We characterized seizure types and frequencies before and after temporal lobectomy for TLE, including consciousness-sparing or consciousness-impairing seizures.Results: Among 241 TLE patients who received temporal lobectomy, 174 (72.2%) patients achieved Engel class I outcome (free of disabling seizures), including 141 (58.5%) with complete seizure-freedom (Engel IA). Predictors of Engel I outcome included lack of generalized seizures, abnormal neuroimaging, localized electroencephalography, and first resection. Overall seizure frequency in patients with persistent postoperative seizures decreased by 70% (p < 0.01), with larger reductions in consciousness-impairing seizures (Fig. 1). While the number of patients experiencing consciousness-sparing SPSs decreased by only 19% after surgery, the number of individuals having consciousness-impairing CPSs and GTCSs diminished by 70% and 68%, respectively (p < 0.001) (Fig. 1). SPS was the predominant seizure type in 19.1% versus 37.0% of patients preoperatively and postoperatively, respectively (p < 0.001). Conclusions: Given important clinical and mechanistic differences between seizures with or without impairment of consciousness, seizure type and frequency remain important considerations in epilepsy surgery.