A questionnaire was mailed to the parents of 70 patients identified by the Sturge-Weber Foundation as recipients of hemispherectomy between 1979 and 2001, and responses obtained from 32 (46%) were analysed at the Johns Hopkins Hospital, Baltimore, MD. The mean age at onset of seizures was 4 months, and the median age at surgery was 1.2 years. Eighty one percent were seizure free, and anticonvulsants were discontinued in 53%. Seizure control was not related to the age at seizure onset, but it did correlate with an older age at operation. Six with continued seizures were operated on at 1.3 years, and in 26 currently seizure-free operation was delayed until age 3.1 years (p=0.05). Hemiparesis was not worsened following surgery. Cognitively, 2 were normal, 10 had mild learning impairment, 14 were moderately learning disabled, and 6 were severely disabled. Cognitive outcome was not related to age at operation or seizure control. 
COMMENT. The main benefit of hemispherectomy in this population is improved seizure control, and the likelihood of seizure freedom is higher when operation is delayed until the child is older.