Longitudinal seizure outcome and prognostic predictors after hemispherectomy in 170 children

Objective: Data on longitudinal seizure outcome after hemispherectomy in children are limited. This study explores the posthemispherectomy longitudinal seizure outcome and its predictors. Methods: We reviewed 186 consecutive children who underwent hemispherectomy between 1997 and 2009 at our center. Clinical, EEG, imaging, and surgical data were collected. Seizure outcome data were collected via a structured questionnaire by contacting families (n = 125) or from the medical records at last follow-up (n = 58). Results: Of 186 patients, 3 were lost to follow-up; 13 seizure-free patients with new-onset nonepileptic spells were excluded. Perioperative complications were not collected. There was no mortality. At a mean follow-up of 5.3 years (±3.3 years), 112 of 170 children (66%) were seizure-free (Engel class 1a). In 58 patients with seizure recurrence, 8 had late remission and 16 had >90% reduction. Overall, at last follow-up, 136 patients (80%) were either seizure-free or had major improvement. Using survival analysis, the estimated probability of seizure freedom after hemispherectomy was 78% (95% confidence interval [CI] = 75%–81%) at 6 months, 76% (95% CI = 73%–79%) at 1 year, 71% (95% CI = 68%–74%) at 2 years, and 63% (95% CI = 59%–67%) at 5 years. On multivariate analysis, bilateral PET abnormalities (risk ratio = 2.53, 95% CI = 1.02–5.85) and acute postoperative seizures (risk ratio = 7.03, 95% CI = 3.07–15.9) independently predicted seizure recurrence. Conclusions: The long-term seizure-free rates after hemispherectomy remained stable at 63% at 5 years and beyond. This study will assist in better candidate selection for hemispherectomy, presurgical counseling, and early identification of surgical failures.