Parkinson’s disease showing progressive conduction aphasia

Abstract

Patients with Parkinson’s disease (PD) may develop progressive dementia late in their clinical course. Dementia in PD is mostly related to neuropathological findings of extensive Lewy bodies (LBs), with or without the coexistence of Alzheimer’s disease (AD) pathology. Aphasia has been reported in patients with LB diseases with AD pathology; however, there have been no reports of typical PD patients developing progressive aphasia during their clinical course. We describe a female PD patient who later developed progressive conduction aphasia characterized by phonemic paraphasia and disturbance in repetition of short sentences without disturbance in writing or auditory comprehension. No episodes of fluctuations of attention, memory complaints, or planning errors were observed. She experienced episodes of visual hallucination. Her low scores on the Mini-Mental State Examination suggested impairment of orientation and attention, and her scores on Raven’s Coloured Progressive Matrices test indicated impaired visuospatial functions. However, her cognitive deficits were not sufficiently severe to impair her daily life. Brain magnetic resonance images revealed atrophy of the left superior temporal gyrus and widening of the left sylvian fissure. [¹⁸F]-fluorodeoxyglucose positron emission tomography revealed glucose hypometabolism in the left cerebral hemisphere. These findings may be related to conduction aphasia. During the progression of PD lesions, the brainstem LB is assumed to take an upward course, extend to the limbic system, and then extend to the neocortex. Conduction aphasia observed in our patient may be associated with an unusual progression of the LB pathology from the brainstem to the left temporoparietal lobe.