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

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