Apraxia of speech and nonfluent aphasia: a new clinical marker for corticobasal degeneration and progressive supranuclear palsy

Purpose of review To highlight the fact that patients with corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) can sometimes present with a progressive apraxia of speech, nonfluent aphasia, or a combination of the two disorders. Recent findings Corticobasal degeneration and PSP are neurodegenerative diseases characterized by neuronal loss and gliosis in cardinal brain regions, as well as the abnormal deposition of the microtubule associated protein tau in cell bodies and cell processes. The typical presenting features of CBD and PSP are akinesia and rigidity that are levodopa unresponsive, although there has been evidence that both diseases, moreso CBD, can present with a dementia syndrome. Recent clinicopathological studies have now also demonstrated that a subset of patients with CBD and PSP present with a progressive apraxia of speech, nonfluent aphasia, or a combination of the two disorders. Summary Presenting features of progressive apraxia of speech or nonfluent aphasia are strongly associated with a diagnosis of CBD, PSP, or both.