THE PLACE OF NEURONAL MIGRATION ABNORMALITIES IN CHILD NEUROLOGY

With the development of modern imaging techniques, disturbances of neu ronal migration appear to be a major cause of epilepsy, mental retarda tion and chronic neurological disability in childhood. Sixty-nine case s are presented, including 46 of diffuse migration abnormalities and 2 3 of localized dysplasia. Patients with diffuse migration disorders pr esented with mental retardation, gross motor impairment and severe sei zure disorders whereas in those with focal anomalies, epilepsy was the chief complaint. Magnetic resonance imaging, although usually diagnos tic of migration disorders often does not allow definition of the path ologic type. Some EEG patterns, such as high amplitude fast rhythms or the theta-delta pattern are highly suggestive. Most cases of abnormal migration are sporadic and probably acquired. Some are due to chromos omal anomalies, especially of chromosome 17p where a gene for lissence phaly has been mapped. Familial cases occur with both recessive and po ssibly dominant inheritance. Epilepsy due to migration abnormalities i s often intractable. Resection of dysplastic cortex may be effective f or localized disease and callosotomy has been proposed for diffuse ano malies.