Mixed transcortical aphasia in nonfamilial dysphasic dementia.

The neurolinguistic and cognitive profiles of a patient with mixed transcortical aphasia and non-familial dysphasic dementia associated with progressive, left perisylvian involution are presented. This clinicopathological entity has recently been shown to be an example of a novel class of intrinsic, focal cortical degenerations with sparing of the basal forebrain. The characteristics of the aphasia were unusual. There were occasional literal and verbal paraphasic errors, but no completion phenomenon, embellishment or significant echolalia. Evidence of a generalized lexical disruption was found on detailed analysis of residual abilities in reading, writing and spelling. A newly described form of non-lexical repetition was present, resulting in the patient's inability to correct syntactical and semantic errors. Affective prosodic repetition was intact. A combined paraphasic word-production and semantic anomia was found. These observations combined with evidence of evolving region-specific cognitive impairments suggest that the pathological process resulted in a relative disconnection of integral frontal and parieto-occipital areas from adjacent perisylvian language zones.