Characteristics of epilepsy in severely mentally retarded individuals

In order to clarify the characteristics of epilepsy in patients with severe mentally retarded (SMR) subjects, we analyzed 52 SMR subjects with epileps y from the institute for SMR subjects at Kikuchi National Hospital, Kumamot o, Japan. A total of 61.5% patients had uncontrolled seizures which were re sistant to treatment. The most common combinations of seizure types in thos e not responding to conventional anticonvulsants were generalized tonic-clo nic seizures (GTCS) with tonic seizure and GTCS with atypical absence. Thei r clinical features were characterized by spastic paralysis associated with a slower background electroencephalogram and abnormal computed tomography scans of the head, suggesting the involvement of cortical damage. These fin dings suggest that a large proportion of epilepsy in SMR subjects does not respond to treatment and that the severity of organic brain damage may ther efore affect the natural course of epilepsy in such patients.