[Neuronal migration anomalies. The magnetic resonance aspects of some types].

The authors investigated the value of magnetic resonance (MR) imaging in the evaluation of some types of neuronal migration anomaly. During pregnancy, a radial neuronal migration from germinal matrix to cortex occurs in the fetal brain, and 6 layers are formed. Infections, traumas, vascular factors can block the migration. Neuronal migration disorders are divided into 5 different classes: (1) agyria-pachigyria complex; (2) schizencephaly; (3) polymicrogyria; (4) unilateral megaencephaly; (5) heterotopia. In this study, 12 patients were evaluated with MR imaging: 5 had lissencephaly, 4 heterotopia and 3 schizencephaly (2 with open lips, and 1 with closed lips). MR imaging is the method of choice in these patients; indeed, characteristic morphologic and signal patterns allow the correct evaluation and diagnosis of neuronal migration anomalies in all cases.