Abstracts

There is a notion that patients whose epilepsy is associated with a putative lesion have better surgical outcomes than those without such lesions. However, cases are often selected and other prognostic often remain unexplored. We explore seizure outcomes in unselected cases of lesional versus non-lesional epilepsy surgery, as well as the variables that impact outcomes in the Calgary Comprehensive Epilepsy Program., A retrospective cohort study of consecutive, unselected cases assessed post-surgical seizure freedom at the time of last follow-up in patients whose MRI showed and in those in whom it did not show putative lesions. We used survival analyses for the main comparison and single and multivariate analyses to explore factors that may influence outcome, such as age, duration of epilepsy, etiology, type of surgery and location of surgery., Of 113 consecutive patients, 91(81%) had putative MRI lesions. An equal proportion (70%) of lesional and non-lesional cases had temporal lobe surgery. Patients without lesions were significantly more likely to have a family history of epilepsy (p=0.03) and they had a trend towards a younger age at surgery. Two years after surgery 57% of lesional and 36% of non-lesional cases were seizure free (p=0.07). As compared with temporal lesional cases, extratemporal lesional cases were younger at presentation (20 vs 38 years) and at surgery (17 vs 35 years) (p [lt] 0.01), and their seizure free rate was lower (not significant). Preoperative deficits were more frequent in non-lesional extratemporal than in temporal cases. Of patients with frontal resections, most were non-lesional (p=0.02)., In unselected patients undergoing epilepsy surgery those without MRI lesions have overall poorer seizure outcomes, are younger (especially extratemporal cases), more often have a family history of epilepsy, and more often have frontal lobe epilepsy.,