The intelligence characteristics of school-aged epileptic children with a history of febrile convulsions

Objective: Febrile convulsion (FC) is the most common seizure disorder in children, and the incidence before age 6 years is 2%-5%. The recurrence rate of FC is 30%-40%, and the rate of subsequent epilepsy is 2%-7%. Many studies have showed that children with FC performed as well as other children in terms of academic progress, intelligence, and behavior. Few have focused on the intelligence outcome of epileptic children with a history of FC. This study delineated the intelligence characteristics of school-aged epileptic children with a history of FC. Patients and Methods: Epileptic children with a history of FC who visited our Pediatric Neurological Clinic from 1997-2000 were enrolled. There were three groups of children between 6 and 12 years old: Epileptic children with a history of FC (FC-epilepsy group), age-matched FC group (FC group), and sibling controls of epileptic children with a history of FC (sibling group). There were thirty children in each group. The study instruments were the Wechsler Intelligence Scale for Children- Third Edition (WISC-III) and magnetic resonance imaging (MRI). Results: The mean age (±SD, months) of the three groups at assessment were as follows: FC-epilepsy group (97.9±18.7), FC group (98.7±18.1), and sibling group (108.1±16.9). The rate of mental retardation (defined as full IQ below 70) in the FC-epilepsy group (36.7%) was higher than that in the FC group (6.7%), and sibling group (3.3%). All test scores from the WISC-III except the digit span subtest in the FC-epilepsy group were significantly lower than those in the FC group. The intelligence scores of the FC-epilepsy children were even worse than the sibling group. The FC-epilepsy group with normal IQ (defined as full IQ>69) had a lower mean score on the coding subtest compared with the other two groups, and they also had a lower mean score on the arithmetic subtest compared with the sibling group. The profiles of intelligence revealed that a significantly poor performance was observed for the coding subtest in the FC-epilepsy group. Ten of the 21 patients who had MRI examinations in the FC-epilepsy group had abnormal findings: Six had hippocampal abnormalities, two had cerebral white matter lesions, one had left cerebral hemispheric atrophy, and one had a frontal lobe tumor. There was no significant difference in the full IQ between children with abnormal and those with normal MRI results in the FC-epilepsy group. Conclusions: We found that the FC-epilepsy group had poorer intellectual performance on all aspects tested, especially in the coding subtest. Epilepsy has significant adverse effects on the intellectual outcome in school-aged children with a history of FC.