[Heterotopic gray matter: A rare cause of epilepsy].

Various etiologic diagnoses are put forward for certain forms of infant epilepsy. We report four cases illustrating a rare cause: gray matter heterotopia. There were three girls and one boy, aged 3 months to 4 years at onset of seizures and 8 to 30 years at diagnosis of gray matter heterotopia. All patients sought healthcare because of repeated seizures. One patient also presented severe mental retardation. No consanguinity was noted. Magnetic resonance imaging showed the interposition of an ectopic ribbon of gray matter within the white matter in all cases. Ectopic gray matter formed bilateral subependymal nodules in one patient and bilateral nodules in the subcortical region suggestive of concentric laminar organization in another. The two other patients presented both of these forms. Other anomalies were associated: partial agenesis of the corpus callosum associated with colpocephaly causing cortical atrophy in one patient and hippocampal sclerosis in another.