Neuro-cognitive development and epilepsy outcome in children with surgically treated hemimegalencephaly.

We performed a long-term follow-up of 10 patients with hemimegalencephaly and refractory epilepsy, after having treated them with hemispherectomy. Before surgery, 9 patients presented with delayed motor and cognitive development. Surgery was performed between age 5 months and 4 years and 8 months; the mean postsurgical follow-up was 5 years and 2 months. The epilepsy improved in most cases: 6 patients became seizure-free and 2 presented only dystonic fits. The cognitive outcome was less favourable, even though some improvement of cognitive competence was found in all. The neurological deficit did not increase after surgery, and the quality of life improved significantly. A good cognitive development before surgery, less severe morphological changes in neuroimaging, and functional and anatomical integrity of the "healthy" hemisphere seem to be associated with a better cognitive outcome.