Intelligence and language of individuals who incurred left hemisphere injury at no later than 3 years of age

: It is generally considered that damage to the brain during infancy and young childhood results in milder or different syndromes than does brain injury incurred during adulthood. However, only several past studies employed CT scans to confirm that lesions are confined to one of the two cerebral hemispheres. We examined intelligence and language skills of 5 cases, which sustained nonprogressive damage exclusively to the left cerebral hemisphere before 1 year of age, and 1 case, which incurred nonprogressive left hemisphere injury at 3 years of age. These cases were tested at 9 to 25 years of age, or 8 to 22 years after inflicting injuries. The following scales and tests, all of which are Japanese versions, were employed: the Wechsler Intelligence Scale for Children-Revised (WISC-R) to measure intelligence of 3 cases at 15 years of age or younger, the Wechsler Adult Intelligence Scale (WAIS) for 3 cases older than 15 years of age, the Western Aphasia Bettery (WAB) to measure language skills, and the shortened version of the Token Test to assess auditory comprehension skills. Upon administration of the tests, we obtained the following results: 1) Although 1 case had a large lesion in the left hemisphere, she exhibited a high IQ of 111, and was adapted well as a college student. The result suggested that large lesions, if incurred at no later than 1 year of age, may affect intelligence to only a little or negligible extent. 2) Verbal IQ generally declines from left hemisphere damage in adults. In all of our subjects, however, verbal IQ was similar to performance IQ.(ABSTRACT TRUNCATED AT 250 WORDS)