The clinical and neuropathological findings in three children with diffuse cortical dysplasia are reported from the Departments of Pathology, Neurology and Pediatrics, University of Rochester Medical Center, Rochester, NY. The children had seizures unresponsive to antiepileptic medication throughout life, they were profoundly mentally retarded, and they died after a progressive neurological deterioration at ages 10 months, 3 years and 7 years. Pathologically, the brains showed generalized cortical dysplasia, without any major malformation of the external gyral pattern. The cortical gray matter was thickened and the demarcation of the gray-white matter junction was indistinct. Microscopically, the cortex contained increased numbers of large neurons with disordered cortical lamination and heterotopic neurons scattered throughout the white matter. The cortical involvement was multifocal involving all lobes of the cerebral hemispheres, and the underlying myelin was pale and rarified. 
COMMENT. The authors report these cases as a newly recognized entity of abnormal neuronal migration. In contrast to classic lissencephaly no distinct lamination of the cortical layers was present and the underlying myelin was also involved. The cause of Generalized Cortical Dysplasia is unknown but a genetic etiologic factor is suspected.