Long-term outcome of surgical treatment of patients with intractable epilepsy associated with schizencephaly.

BACKGROUND: Schizencephaly is a developmental anomaly of the brain that is sometimes associated with intractable seizures. Patients that suffer from medically refractory seizures may be considered for surgical treatment.

METHOD: Five patients with intractable epilepsy associated with schizencephaly were studied. Evaluation methods included medical history assessment, neurological examination, magnetic resonance imaging (MRI) with three-dimensional (3D) surface rendering, positron emission tomography (PET), video-electroencephalogram (EEG) monitoring with surface electrodes and subdural grid electrodes, sodium amobarbital test, and neuropsychological assessments. Topectomy was performed close to the schizencephalic cleft in two patients, and at an area distant from the cleft in one under the guidance of electrocorticography (ECoG). Temporal lobectomy was performed in two patients.

RESULTS: MRI revealed unilateral schizencephaly in all five patients. Video-EEG monitoring recorded simple partial seizures in two patients and complex partial seizures in three patients. The epileptogenic zone was localized close to the schizencephalic cleft in two patients, distant to the cleft in one patient, and in the temporal lobe in two patients. Postoperatively, one of two patients with temporal lobectomy and one of three patients with topectomy were seizure-free at 1-year follow-up. Three patients experienced marked seizure reduction but were not seizure-free at 1 year; however, at the follow-up periods of 2.5 years and 6.5 years, two of these three patients were seizure free. One patient who underwent temporal lobectomy began to have very brief losses of consciousness lasting 1-3 s (3-4 times per year). Neurological complications included temporary upper monoparesis in one and hemiparesis in one.

CONCLUSIONS: The abnormal cortex lining schizencephalic clefts and cortical tissues near the cleft may be epileptogenic. Areas distant to the cleft may also be the source of seizures. Careful evaluation should be performed to define the epileptogenic zone in patients with intractable epilepsy associated with schizencephaly, and meticulous resection of the epileptogenic zone can lead to good seizure control.