[Disorders of neuronal migration: clinical and radiological signs in 21 patients].

We describe 21 patients affected by neuronal migration disorders. The main clinical manifestations were epilepsy, hemiparesis with hemiatrophy and psychomotor retardation. The neuronal migration disorders most frequently diagnosed were various forms of heterotopia and schizencephaly. Magnetic resonance imaging was more sensitive and specific that computed tomography in the diagnosis of these disorders. Schizencephaly correlates well with hemiparesis and hemiatrophy, as does nodular heterotopia with focal epilepsy and diffuse neuronal migration disorders with severe encephalopathies.