Abstracts

Rationale: There is limited information on outcome after hemispherectomy performed in adolescents and adults because this procedure is rarely performed in adults with refractory epilepsy. Most adult hemispherectomy series are small, with limited information on factors affecting functional and seizure outcome. Thus, identification of prognostic factors that influence the seizures and functional outcome would aid in preoperative counseling. Concerns regarding risk to language, cognitive dysfunction, and motor weakness after hemispherectomy may be limiting the application of this surgical procedure in these patients.  Methods: We reviewed 47 consecutive patients older than 16 years of age who underwent hemispherectomy between 1996 and 2016 at our center. Clinical, EEG, imaging, neuropsychological, surgical and functional status data were analyzed. Seizure outcome data were collected from the medical record at last follow-up. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom. Univariate and multivariate analyses were then used to identify prognostic indicators of seizure freedom.  Results: Thirty-six patients were aged 18 or older at surgery; 11 were aged between 16 and 18 years. Brain injury that lead to hemispheric epilepsy occurred before 10 years of age in 41 (87%) patients. At a mean follow up of 5.3 postoperative years (median 2.9 years), 36 (77%) were Engel class I. Longitudinal outcome analysis showed 84% seizure freedom (Engel IA) at 6 months, 76% at 2 years, and 76% at 5 years and beyond with stable longitudinal outcomes up to 12 years from surgery. Multivariate analysis demonstrated that acute post-operative seizures and contralateral interictal spikes at 6 month follow-up EEG were associated with poor seizure outcome. Patients who could walk unaided pre-operatively and had no cerebral peduncle atrophy on brain MRI were more likely to experience worsening post-operatively. Otherwise, post-operative ambulatory status and hand function were unchanged. Of the 19 patients who completed neuropsychological testing, 17 demonstrated stable or improved post-operative outcomes. Conclusions: Hemispherectomy in adults is a safe and effective procedure, with seizure freedom rates and functional outcome similar to that observed in children.  Funding: No funding