Unilateral closed-lip schizencephaly and epilepsy: a comparison with cases of unilateral polymicrogyria.

We compared the electroclinical features and evolution of patients with two different types of abnormal cortical organization: unilateral closed-lip schizencephaly (SCHZ) and unilateral polymicrogyria (PMG). Between February 1990 and June 2002, 51 children with either unilateral PMG or closed-lip SCHZ were selected through neuroradiological analysis for investigation at our service. We evaluated the frequency of epilepsy, electroclinical features and evolution. The mean time of follow-up was 7 years (range 1-12 years). All patients underwent neurological examination, computed tomography scan and magnetic resonance imaging, serial electroencephalographic (EEG) recordings and neuropsychological assessment. Thirty-six of the 51 patients had unilateral PMG. All patients had hemiparesis with mild spasticity. Mental retardation was mild in 20 and moderate in 14. In two patients IQ was normal. Partial motor seizures were recorded in 28 patients, with secondary generalization in 20. The median age at onset of seizures was 2 years (range 4 months-7 years). Interictal EEGs showed unilateral spikes in all patients. In 21 patients epilepsy worsened between the ages of 4 and 8 (mean 5.6 years) with frequent atonic seizures, atypical absences, epileptic negative myoclonus and gait difficulties. EEGs showed continuous spike-wave activity or bilateral high-frequency spike discharges during slow-wave sleep. Frequent relapses of atonic and myoclonic seizures were seen in nine patients. At present, 16 patients are seizure-free. Fifteen patients with unilateral SCHZ were included in the study. Focal motor seizures were registered in seven cases, in three of them with secondary generalization. The median age at onset of epilepsy was 2.5 years (range 1-4 years). Interictal EEGs showed unilateral spikes in these seven cases. All patients except one presented mild spastic hemiparesis. Mental retardation was mild in ten children, moderate in two and IQ was normal in three. Although the underlying mechanisms leading to PMG and SCHZ are probably similar, the electroclinical phenomenon of secondary bilateral synchrony with frequent negative myoclonus was not present in our cases with unilateral closed-lip SCHZ.