Primary Progressive Aphasias and Apraxia of Speech

Abstract

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.

Non-fluent/Agrammatic Variant of Primary Progressive Aphasia With Generalized Auditory Agnosia

“…The anterior components of the language network, including the inferior frontal lobe, and the anterior opercular and perisylvian areas, including the anterior insula and superior temporal gyrus, have been implicated as the neuroanatomical substrates of nfvPPA ( 14 ). The lesions identified in our case correspond to these areas and may therefore account for the observed language impairments, including generalized auditory agnosia, which is seldom observed in typical nfvPPA.…”

Primary progressive aphasia: misdiagnosis with ‘normal imaging’

“…Although there are some controversies, three clinical variants of primary progressive aphasia (PPA) are generally recognised: the non‐fluent/agrammatic variant (nfvPPA or avPPA), in which there may or may not also be an apraxia of speech (AOS); the semantic variant (svPPA), and the logopenic variant (lvPPA) 1,2 . While nfvPPA and svPPA are characterised as linguistic variants of frontotemporal dementia (FTD), 3 lvPPA is most often associated with Alzheimer‐type pathology and is therefore classified with Alzheimer's disease (AD) 4 .…”

Progressive apraxia of speech in Quebec French speakers: A case series

“…Primary progressive apraxia of speech (PPAOS) is a neurodegenerative syndrome characterized by progressive and initially isolated (or predominant) AOS (Duffy 2006, Josephs et al 2012. Although the classification of PPAOS as a distinct disorder from the non-fluent variant of primary progressive aphasia (nfvPPA) was suggested more than a decade ago, its application and definition remain variable (Botha and Josephs 2019). Indeed, some authors have suggested that PPAOS includes all patients with AOS as the predominant symptom (Harris et al 2013, Josephs et al 2010, 2013, Josephs et al 2006, Mesulam 2013.…”

“…The distinction of patients with predominant AOS (isolated or not) from those with nfvPPA is motivated by recent studies suggesting differences in the underlying neurophysiology (Utianski et al 2019) and pathology, neuroimaging abnormalities (Josephs et al 2013), clinical manifestations (Josephs et al 2013), and disease progression (Whitwell et al 2017). Further, it has important implications for clinical management (Botha and Josephs 2019, Josephs et al 2013. Comparably, the need to further categorize patients with PAOS into PPAOS or DAOS subcategories is motivated not only by the presence of agrammatism but also by possible differences similar to what is observed between PAOS and nfvPPA (i.e., neuroimaging, clinical manifestations, disease progression, etc.…”

“…; Duffy et al 2020). For the purpose of the present study, the classification from Botha and Josephs (2019) will be used: PAOS refers to the cluster of degenerative syndromes with predominant AOS, comprised of primary progressive apraxia of speech without aphasia (PPAOS) and dominant progressive apraxia of speech with concomitant aphasia of milder severity than the AOS (DAOS).…”