Predictors of surgical outcome in medically-resistant temporal lobe epilepsy with bilateral features on pre-operative evaluation

• We evaluate prognostic factors for favorable temporal resection outcomes in bilateral cases.
• Lateralized neuropsychological and Wada test were significantly associated with outcomes.
• Seizure reduction and freedom is possible in patients with bilateral features.
• Temporal resection should be considered in patients with lateralized pre-operative exams.

ObjectiveThis study identifies potential prognostic factors for favorable anterior mesial temporal lobe (AMTL) resection outcomes in patients with medically refractory temporal lobe epilepsy (TLE) with bilateral features on pre-operative examination.MethodsThirty-one patients demonstrated bilateral features defined as: bilateral independent temporal or bitemporal ictal onsets on surface or intracranial EEG, or bitemporal interictal epileptiform abnormalities on surface EEG with bilateral radiographic mesial temporal sclerosis. Surgical outcomes were classified according to reduction in seizure frequency: I (100% reduction), II (≥75% reduction), III (50–74% reduction), IV (<50% reduction).ResultsOf 31 patients, 14 (45%) improved to class I and 9 (29%) had a class II outcome at an average of 4 years after surgery. Eight (26%) patients did not exhibit good surgical outcome (class III, class IV). We found that neuropsychological and Wada memory scores were significantly correlated (p < 0.05) with surgical outcome, and logistic regression found neuropsychological evaluation significantly predicted better surgical outcome (p < 0.05).ConclusionsWhen bilateral features are present on pre-operative evaluation, neuropsychological and Wada test results can provide unique data to better identify those patients more likely to achieve substantial seizure reduction.