Abstracts

Hemispherectomy has been performed for the past 60 years for hemispheric epilepsy. However, few papers report the seizure outcome of patients with malformations of cortical development submitted to hemispherectomies and the variables associated with persistent seizures after surgery.
Twenty-seven patients diagnosed with intractable epilepsy and malformations of cortical development (MCD) underwent hemispherectomies (anatomical or functional) from February 1997 to March 2002. Pre and postoperative evaluation included video-EEG monitoring, MR imaging, PET and neuropsychological testing. Seizure outcome was correlated with variables associated with persistent postoperative seizures (surgical technique, seizure duration, bilateral MR findings, bilateral ictal and interictal activity, PET abnormalities and diagnosis categories). The Fisher test and the Chi-test were applied as statistical analyses. The level of significance was 0.05.
The mean follow-up 26.4 months. The mean age at the time of surgery was 4.9 years. Diagnosis included focal cortical dysplasia (17 patients), hemimegaloencephaly (9 patients) and schizencephaly (1 patient). The mean seizure duration was 49.2 months. Seizure control rate was 74%. Complication rate was 14% (hydrocephalus and infection). Five patients were submitted to VP shunts. No fatalities occurred. Thirteen anatomical hemispherectomies and 18 functional hemispherectomies were performed. Incomplete disconnection (evidenced in postoperative images), bilateral preoperative MR findings and bilateral PET abnormalities were associated with postoperative persistent seizures (p[lt]0.05). Bilateral interictal and ictal epileptiform activities, diagnosis and seizure duration were not associated with persistent seizures after surgery. The most common region of incomplete disconnection was the basal frontal cortex, especially in the hemimegaloencephaly subgroup. In this subgroup, functional hemispherectomy was associated with unsatisfactory seizure outcome when compared to anatomical hemispherectomy technique.
In the studied group, the overall rate of seizure freedom is encouraging, with a satisfactory complication rate. Attention to technique during disconnection and anatomy familiarity (especially in the basal posterior frontal region) are mandatory. Bilateral PET and MR findings may indicate a less satisfactory seizure control prognosis. In patients with hemimegaloencephaly, anatomical hemispherectomy was the surgical technique associated the best outcome.