Electroencephalographic study of 137 patients with thalidomide embryopathy

EEG examinations were carried out on 137 patients with thalidomide embryopathy aged between 7 and 22 with a mean age of 17.0. Waking and sleep EEGs were normal in 82 (59.9%), and abnormal in 55 (40.1%). The incidence of abnormal EEG was significantly high in the patients associated with mental retardation, and it increased in proportion to the severity of mental retardation. The most frequent abnormal EEG finding was slowing of the basic activity (35/137; 24.8%). The incidence of slowing was significantly higher in the patients with a sensorineural hearing impairment (26/74; 35.1%) than in those with dysmelia (9/62; 14.5%). Slowing appeared frequently in the patients with various cranial nerve symptoms (30/84; 35.7%). The incidence of slowing was found significantly high in the patients with borderline or subnormal intelligence (8/16; 50.0%), and it correlated with the severity of mental retardation. Many patients (48/84; 57.1%) showed unilateral or asymmetrical neurological symptoms. However, asymmetry or focal abnormality in EEG was shown in only 8 patients. Positive spikes appeared frequently in the patients with gonadal dysplasia. Other somatic symptoms, past medical history and family history were not related to the incidence of abnormal EEGs. Eight patients had had epileptic seizures prior to this examination. Another 2 patients had nocturnal enuresis and showed epileptic EEG abnormalities in this examination. The incidence of epilepsy was significantly higher in the patients we examined than among the general population. It is concluded that ingestion of thalidomide during pregnancy affected not only the morphological development of the limbs of the fetus, but the functions of its central nervous system, causing hearing impairment, other cranial nerve symptoms, mental retardation or epilepsy.