Abstracts

Rationale: Hemispherectomy is a rare surgical option for carefully selected children with intractable lateralized/hemispheric epilepsies. Only one previous study addressed outcome after hemispherectomies in adults (age > 18 years) with intractable epilepsy. Methods: Charts were retrospectively reviewed for adult patients who underwent either anatomical or functional hemispherectomy in the past 12 years at The Cleveland Clinic. Variables included pre- and post-surgical clinical data, including clinical examination, seizure type, seizure frequency, and antiepileptic medication use. Wilcoxon test was used to compare pre and postoperative variables. Statistics were done using SPSS 10.0 for Windows (SPSS Inc., Chicago, IL). Results: Patient descriptives and frequency of hemispherectomy: Among 810 adults undergoing epilepsy surgery, we identified 13 adult patients (1.6%) who underwent either functional (12) or anatomical (1) hemispherectomy. Seven patients had undergone neurosurgical interventions prior to the hemispherectomy due to intractable epilepsy. The average age of seizure onset was 8.7 years (10 patients had onset prior to age 10 years including 6 patients with onset prior to age 3 years) with the average age at surgery being 31.3 years (range 18-56 years). All 13 patients had contralateral hemiparesis on examination, and (widespread) ipsilateral abnormalities on MRI. Findings include encephalomalacia (9), porencephaly (1), cortical dysplasia (2), arteriovenous malformation (1), and Rasmussen encephalitis (1). Outcome: Average follow-up was 42 months with an average reduction by one antiepileptic medication (2.8 to 1.8 AEDs) at that time (p<0.05). Eight patients were seizure-free at the last follow-up and the remaining four patients had an average seizure frequency reduction of 86.9% (range 77.3 to 99.3%). Complications: Five patients had post-operative complications (aseptic meningitis or hydrocephalus). There was no mortality directly related to the hemispherectomy. In addition to pre-existing hemiparesis, four patients developed a postoperative homonymous hemianopsia. Conclusions: Hemispherectomy is an effective surgical option in carefully selected adult patients, resulting in improved long-term seizure control, reduction in antiepileptic medication use, limited postsurgical complications, and no mortality. Inclusion criteria for good prognosis included intractable hemispheric epilepsy, preoperative contralateral hemiparesis, and early onset of seizures. Homonymous hemianopsia is an infrequent but expected postoperative side effect.