Abstracts

Hemispherectomy has been performed for refractory epilepsy in association with unilateral hemispheric abnormalities and hemiplegia for over 60 years.The classic anatomic hemispherectomy is now rarely performed due to complications such as superficial hemosiderosis. The most recent procedure is functional hemispherectomy. Studies have shown general improvement and significant seizure control, however only a few studies have been done with mixed results regarding cognitive outcome. The purpose of this study is to evaluate long term outcome of children undergoing functional hemispherectomy in a single pediatric epilepsy surgery center over a 10 year period. A retrospective chart review of the children undergoing functional hemispherectomy at The Hospital for Sick Children ,(Toronto, Canada), from 1993-2003 was done. A data abstraction sheet was used to collect information on etiology, seizure outcome, anticonvulsant medications use, pre and post surgical neuropsychology assessment. 14 children were identified. Follow-up post hemispherectomy ranged from 16 months to 9.5 years (mean 6 years). Age at surgery was 3.5 months- 16 years (median 6.5 years) .The underlying pathology was developmental in 9 patients (6 hemimegalencephaly, 3 multifocal cortical dysplasia), acquired in 1 ( 1 post encephalitis) and progressive in 4 ( 3 Rasmussen[apos]s encephalitis, 1 Sturge-Weber syndrome). At follow-up, 12/14 were completely or nearly completely seizure free ( Engel class I and II). Seizure freedom was better in patients with progressive and acquired pathology (4/6) compared to developmental pathology ( 1/9). 4/14 are no longer taking anticonvulsant medications. After surgery, seizure frequency was further improved in 3 patients by modifiying the anticonvulsants. The hemiplegia (but not fine motor movements) remained unchanged in 9 , improved in 3 and deteriorated in 3 children.12/14 have normal ambulation. In 4/6 children who had left hemispherectomy, language development was regained or continued to develop normally. Pre-surgical behavioral problems remained unchanged or improved after hemispherectomy in all the patients. Neuropsychology outcome continues to be analyzed. In this small retrospective long term outcome study, children benefited from hemispherectomy, especially with aquired or progressive etiology. The majority had an excellent outcome regarding seizure freedom. Motor disability was unchanged or improved in most children. Languge was preserved in the majority of left hemispherectomies. Post hemispherectomy seizure reduction can be further improved with pharmacological management.