Neural substrates of verbal repetition deficits in primary progressive aphasia.

In this cross-sectional study, we examined the relationship between cortical thickness and performance on several verbal repetition tasks in a cohort of patients with primary progressive aphasia in order to test predictions generated by theoretical accounts of phonological working memory that predict phonological content buffers in left posterior inferior frontal sulcus and supramarginal gyrus. Cortical surfaces were reconstructed from magnetic resonance imaging scans from 42 participants diagnosed with primary progressive aphasia. Cortical thickness was measured in a set of anatomical regions spanning the entire cerebral cortex. Correlation analyses were performed between cortical thickness and average score across three phonological working memory-related tasks: the Repetition sub-test from the Western Aphasia Battery, a forward digit span task, and a backward digit span task. Significant correlations were found between average working memory score across tasks and cortical thickness in left supramarginal gyrus and left posterior inferior frontal sulcus, in support of prior theoretical accounts of phonological working memory. Exploratory whole-brain correlation analyses performed for each of the three behavioural tasks individually revealed a distinct set of positively correlated regions for each task. Comparison of cortical thickness measures from different primary progressive aphasia sub-types to cortical thickness in age-matched controls further revealed unique patterns of atrophy in the different subtypes.R01 DC007683 - NIDCD NIH HHSPublished versio

Differential Diagnosis of Apraxia of Speech in Children and Adults: A Scoping Review

Purpose: Despite having distinct etiologies, acquired apraxia of speech (AOS) and childhood apraxia of speech (CAS) share the same central diagnostic challenge (i.e., isolating markers specific to an impairment in speech motor planning/ programming). The purpose of this review was to evaluate and compare the state of the evidence on approaches to differential diagnosis for AOS and CAS and to identify gaps in each literature that could provide directions for future research aimed to improve clinical diagnosis of these disorders. Method: We conducted a scoping review of literature published between 1997 and 2019, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. For both AOS and CAS, literature was charted and summarized around four main methodological approaches to diagnosis: speech symptoms, quantitative speech measures, impaired linguistic- motor processes, and neuroimaging. Results: Results showed that similar methodological approaches have been used to study differential diagnosis of apraxia of speech in adults and children; however, the specific measures that have received the most research attention differ between AOS and CAS. Several promising candidate markers for AOS and CAS have been identified; however, few studies report metrics that can be used to assess their diagnostic accuracy. Conclusions: Over the past two decades, there has been a proliferation of research identifying potential diagnostic markers of AOS and CAS. In order to improve clinical diagnosis of AOS and CAS, there is a need for studies testing the diagnostic accuracy of multiple candidate markers, better control over language impairment comorbidity, more inclusion of speech-disordered control groups, and an increased focus on translational work moving toward clinical implementation of promising measures

Table e-3. Operational guidelines for motor speech severity ratings

Table e-3. Operational guidelines for motor speech severity rating

Table e-1. Baseline speech/language characteristics per patient

Table e-1. Baseline speech/language characteristics per patien

Data from: Quantification of motor speech impairment and its anatomic basis in primary progressive aphasia

Objective: To evaluate whether a quantitative speech measure is effective in identifying and monitoring motor speech impairment (MSI) in patients with primary progressive aphasia (PPA), and to investigate the neuroanatomical basis of MSI in PPA. Methods: Sixty-four patients with PPA were evaluated at baseline, with a subset (N=39) evaluated longitudinally. Articulation rate (AR), a quantitative measure derived from spontaneous speech, was measured at each timepoint. MRI was collected at baseline. Differences in baseline AR were assessed across PPA subtypes, separated by severity level. Linear mixed-effects models were conducted to assess groups differences across PPA subtypes in rate of decline in AR over a one-year period. Cortical thickness measured from baseline MRIs was used to test hypotheses about the relationship between cortical atrophy and MSI. Results: Baseline AR was reduced for patients with non-fluent variant PPA (nfvPPA), as compared to other PPA subtypes and controls, even in mild stages of disease. Longitudinal results showed a greater rate of decline in AR for the nfvPPA group over one year, as compared to logopenic and semantic variant subgroups. Reduced baseline AR was associated with cortical atrophy in left-hemisphere premotor and supplementary motor cortices. Conclusions: The AR measure is an effective quantitative index of MSI that detects MSI in mild disease stages and tracks decline in MSI longitudinally. The AR measure additionally demonstrates anatomic localization to motor-speech specific cortical regions. Our findings suggest that this quantitative measure of MSI might have utility in diagnostic evaluation and monitoring of motor speech impairments in PPA

Figure e-1. Motor speech regions of interest labelled using SpeechLabel parcellation paradigm

Figure e-1. Motor speech regions of interest labelled using SpeechLabel parcellation paradig

Table e-2. Supplemental CDR language domain as defined by Knopman, Weintraub, and Pankratz (2011)

Table e-2. Supplemental CDR language domain as defined by Knopman, Weintraub, and Pankratz (2011

Table e-5. Motor speech characterizations (consensus ratings) per patient

Table e-5. Motor speech characterizations (consensus ratings) per patien

Table e-4. Motor speech features and criteria for diagnosing AOS, Dysarthria

Table e-4. Motor speech features and criteria for diagnosing AOS, Dysarthri