Language functions in progressive supranuclear palsy.

Language functions were studied in 6 patients with clinically diagnosed progressive supranuclear palsy who conformed to the characteristic pattern of 'subcortical dementia'. Dysarthria, reading difficulties and disturbances of handwriting were present in all patients. Some patients showed additional deficits including visual dyslexia, constructional dysgraphia and an increased rate of self-corrections and misnamings in object confrontation naming. In most instances, the naming errors referred to an object visually similar to the target object, suggesting that visual misperception is the major cause of the naming disorder. It is concluded that a variety of language impairments may develop secondary to other neurological and neuropsychological changes in progressive supranuclear palsy.