The WAIS as a lateralizing and localizing diagnostic instrument: a study of 656 patients with unilateral cerebral lesions.

A retrospective study of 656 patients with unilateral cerebral lesions is reported. Their performance on a shortened version of the WAIS was assessed in relation to laterality of lesion and to localization of lesion within a hemisphere. The Verbal IQ measure was impaired in all the left-hemisphere localization subgroups compared with the corresponding right-hemisphere localization subgroups. The converse was not the case, the Performance IQ measure was only significantly impaired in two localization groups, the group with lesions restricted to the right parietal lobe and the larger group consisting of all patients with right parietal involvement. With the exception of a selective impairment on the Block Design and Picture Arrangement in the group consisting of all patients with right parietal involvement, there was no evidence of distinctive patterns of impairment associated with any localization subgroup. A right-and left-hemisphere index based on the major laterality impairments were computed for each patient. These indices were used to assess the relationship between aetiology of lesion and sex and patterns of impairment. Although overall hemisphere differences and laterality index differences were obtained, there was only a minor interaction with aetiology and there was no evidence of differential patterns of impairment associated with sex.