Classification and clinicoradiologic features of primary progressive aphasia (PPA) and apraxia of speech

Abstract

The consensus criteria for the diagnosis and classification of primary progressive aphasia (PPA) have served as an important tool in studying this group of disorders. However, a large proportion of patients remain unclassifiable whilst others simultaneously meet criteria for multiple subtypes. We prospectively evaluated a large cohort of patients with degenerative aphasia and/or apraxia of speech using multidisciplinary clinical assessments and multimodal imaging. Blinded diagnoses were made using operational definitions with important differences compared to the consensus criteria. Of the 130 included patients, 40 were diagnosed with progressive apraxia of speech (PAOS), 12 with progressive agrammatic aphasia, 9 with semantic dementia, 52 with logopenic progressive aphasia, and 4 with progressive fluent aphasia, while 13 were unclassified. The PAOS and progressive fluent aphasia groups were least impaired. Performance on repetition and sentence comprehension was especially poor in the logopenic group. The semantic and progressive fluent aphasia groups had prominent anomia, but only semantic subjects had loss of word meaning and object knowledge. Distinct patterns of grey matter loss and white matter changes were found in all groups compared to controls. PAOS subjects had bilateral frontal grey matter loss, including the premotor and supplementary motor areas, and bilateral frontal white matter involvement. The agrammatic group had more widespread, predominantly left sided grey matter loss and white matter abnormalities. Semantic subjects had bitemporal grey matter loss and white matter changes, including the uncinate and inferior occipitofrontal fasciculi, whereas progressive fluent subjects only had left sided temporal involvement. Logopenic subjects had diffuse and bilateral grey matter loss and diffusion tensor abnormalities, maximal in the posterior temporal region. A diagnosis of logopenic aphasia was strongly associated with being amyloid positive, (46/52 positive). Our findings support consideration of an alternative way of identifying and categorizing subtypes of degenerative speech and language disorders.

Temporal acoustic measures distinguish primary progressive apraxia of speech from primary progressive aphasia

“…The criteria and methods for diagnosing PPAOS and PPA and its variants have been described elsewhere (Botha et al ., 2015; Josephs et al ., 2012, 2013). …”

A Young Man With Progressive Language Difficulty and Early-Onset Dementia

“…2 More specifically, within the PPA framework, the patient's presentation is most consistent with semantic dementia (SD), or the semantic variant of PPA. 1,3 As one of the language variants of frontotemporal dementia, it is well known to result in a secondary behavioral syndrome in a subset of patients. ).…”

Primary progressive aphasia: conceptual evolution and challenges

“…However, they consider unclassifiable cases and cases with pure anomia as separate variants. 32,51 Although the authors demonstrated clinical-neuroanatomical coherence in each variant, and a clinicopathological series with refined syndrome characterization revealed some comparable associations, 52 it is not clear if this cross-sectional taxonomy remains stable in a long-term follow-up. Longitudinal studies tracking deficits and atrophy changes over years as well as pathological confirmation may confirm the clinical applicability and biological validity of this proposal against others.…”

“…Not so different from Kertesz's classifications, the group at the Mayo Clinic subsequently proposed a classification system with six clinical variants, based on a comprehensive clinical speech and language assessment and neuroimaging analysis in a large cohort. 32 In contrast to other classification systems, this group first divides cases with predominantly movement-based speech alterations, the so-called primary progressive apraxia of speech, 51 from those cases that evince predominantly linguistic involvement indicative of an aphasia. Therefore, the previously single entity of nfv-PPA is separated into two variants: progressive agrammatic aphasia and progressive apraxia of speech.…”

“…31 Although different solutions have been proposed to overcome this issue, the optimal approach is still under debate. Whereas some groups pose the subdivision into new subvariants so as to better refine each PPA syndrome and thus improve diagnostic accuracy and pathological prediction, 32 others disregard the existence of lv-PPA and restrict the classification into only two variants. 31 These opposite views remain unsolved and open the old taxonomic dispute between "lumpers" and "splitters".…”