Aphasia and handedness in relation to hemispheric side, age at injury and severity of cerebral lesion during childhood.

The effects of the variables of hemispheric side of lesion, age at injury and severity of cerebral damage on language performance and hand dominance were investigated in groups of hemiparetic children. Severity of cerebral damage was defined by the degree of structural abnormality shown on computed tomography (CT) scans. Tests of auditory verbal comprehension and object naming were used as indicators of productive and receptive language skills. The responses to a series of questions on a handedness inventory provided a rated measure of hand dominance. The results indicated that language deficits characterize the performance of all patient groups with left cerebral injuries. Impairments are more profound, however, in the case of left hemisphere injuries acquired after the age of 5 years. In addition, prenatal and early postnatal left cerebral lesions consistently result in strong sinistrality. It is concluded that the crucial variable underlying the demonstration of language deficits and left hand dominance is not severity of lesion but age at injury and hemispheric side of lesion.