Acute postoperative seizures and long-term seizure outcome after surgery for hippocampal sclerosis

Purpose: To assess the incidence and the prognostic value of acute postoperative seizures (APOS) in patients surgically treated for drug-resistant temporal lobe epilepsy due to hippocampal sclerosis (TLE-HS). Methods: We studied 139 consecutive patients with TLE-HS who underwent epilepsy surgery and were followed up for at least 5 years (mean duration of follow-up 9.1 years, range 5-15). Medical charts were reviewed to identify APOS, defined as ictal events with the exception of auras occurring within the first 7 days after surgery. Seizure outcome was determined at annual intervals. Patients who were in Engel Class Ia at the last contact were classified as having a favorable outcome. Results: Seizure outcome was favorable in 99 patients (71%). Six patients (4%) experienced APOS and in all cases their clinical manifestations were similar to the habitual preoperative seizures. All patients with APOS had unfavorable long-term outcome, as compared with 35 (26%) of 133 in whom APOS did not occur (p <0.001). Conclusions: Our study suggests that APOS, despite being relatively uncommon in patients undergoing resective surgery for TLE-HS, are associated with a worse long-term seizure outcome. Given some study limitations, our findings should be regarded as preliminary and need confirmation from future larger, prospective, multicenter studies.