Band heterotopias: a newly recognized neuronal migration anomaly.

Five patients with a continuous band of heterotopic neurons between the lateral ventricles and the cerebral cortex are described. All patients presented with intractable seizures and moderate-to-severe developmental delay. The identification of this anomaly is difficult because of its symmetry and the minimal abnormality of the gyral pattern of the cortex. The possible embryogenesis of the anomaly is discussed. The identification of these band heterotopias is important because of the intractable nature of the seizure disorder and the poor prognosis for the patient.