Primary Progressive Aphasias and Apraxia of Speech

Hugo Botha, MBChB; Keith A. Josephs, MD, MST, MSc p. 101-127 February 2019, Vol.25, No.1 doi: 10.1212/CON.0000000000000699
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PURPOSE OF REVIEW: This article reviews two of the primary progressive aphasias (PPAs), disorders characterized by the early and predominant impairment of language, and primary progressive apraxia of speech, a degenerative motor speech disorder that is closely related to PPA. An outline of the history and controversy surrounding how these disorders are classified is provided before the article focuses on each disorder’s clinical and imaging features.

RECENT FINDINGS: Over the past decade, the classification of degenerative speech and language disorders has been refined. Clinical, imaging, and pathologic evidence suggests that primary progressive apraxia of speech is a distinct degenerative disorder. Furthermore, multiple lines of evidence have highlighted issues with nonfluent/agrammatic variant PPA, which complicates the diagnosis, prognosis, and study of this disorder. Semantic variant PPA, while not without controversy, remains one of the most well-defined disorders, with good clinicopathologic correlation.

SUMMARY: Accurate classification and diagnosis of these degenerative speech and language disorders is crucial in clinical practice and ongoing research efforts. For nonfluent/agrammatic variant PPA, the authors suggest emphasizing agrammatism as the core inclusion criterion and taking care not to include patients with isolated or predominant apraxia of speech. Isolated apraxia of speech can be the manifestation of a degenerative disease and, based on the different prognosis, should be recognized as distinct from PPA. Finally, it is important to recognize that some patients with semantic dementia, despite sharing the same pathologic associations, may not meet criteria for PPA.

Address correspondence to Dr Keith A. Josephs, Department of Neurology, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, Josephs.Keith@mayo.edu.

RELATIONSHIP DISCLOSURE: Dr Botha receives research/grant support from the National Institutes of Health (R01 DC012519-06). Dr Josephs receives research/grant support from the National Institutes of Health (R01 AG37491, R01NS89757, R01 DC14942).

UNLABELED USE OF PRODUCTS/INVESTIGATIONAL USE DISCLOSURE: Drs Botha and Josephs report no disclosures.

© 2019 American Academy of Neurology.