Psychological effects of subclinical epileptiform EEG discharges in children. II. General intelligence tests.

Twenty-one children with suspected or proven epilepsy and subclinical epileptiform EEG discharges in the waking state were studied. The EEG was telemetered and behaviour recorded by closed-circuit television during performance of a general intelligence test (RAKIT, shortened version) which comprised 6 subtests. Mean total IQ was below that of control populations and the subtests profile was abnormal, due particularly to impaired performance on a subtest concerned with verbal short-term memory. This effect was accounted for by that subgroup of children who exhibited discharges during the test; those who did not show discharges at that time were unimpaired. Performance of 3 of the subtests was impaired when discharges occurred during presentation of the test item or between presentation and response. The findings suggest that cognitive impairment found in people with epilepsy may not only represent a more or less static disability, due to drugs, cerebral pathology, etc., but may in part be an intermittent process related to the occurrence of subclinical epileptiform discharges. These preliminary findings need to be amplified but have implications both for interpretation of neuropsychological studies in persons with epilepsy and also for the drug treatment of those who continue to exhibit subclinical EEG discharges when overt seizures have been controlled.