Logopenic and nonfluent variants of primary progressive aphasia are differentiated by acoustic measures of speech production

Differentiation of logopenic (lvPPA) and nonfluent/agrammatic (nfvPPA) variants of Primary Progressive Aphasia is important yet remains challenging since it hinges on expert based evaluation of speech and language production. In this study acoustic measures of speech in conjunction with voxel-based morphometry were used to determine the success of the measures as an adjunct to diagnosis and to explore the neural basis of apraxia of speech in nfvPPA. Forty-one patients (21 lvPPA, 20 nfvPPA) were recruited from a consecutive sample with suspected frontotemporal dementia. Patients were diagnosed using the current gold-standard of expert perceptual judgment, based on presence/absence of particular speech features during speaking tasks. Seventeen healthy age-matched adults served as controls. MRI scans were available for 11 control and 37 PPA cases; 23 of the PPA cases underwent amyloid ligand PET imaging. Measures, corresponding to perceptual features of apraxia of speech, were periods of silence during reading and relative vowel duration and intensity in polysyllable word repetition. Discriminant function analyses revealed that a measure of relative vowel duration differentiated nfvPPA cases from both control and lvPPA cases (r2 = 0.47) with 88% agreement with expert judgment of presence of apraxia of speech in nfvPPA cases. VBM analysis showed that relative vowel duration covaried with grey matter intensity in areas critical for speech motor planning and programming: precentral gyrus, supplementary motor area and inferior frontal gyrus bilaterally, only affected in the nfvPPA group. This bilateral involvement of frontal speech networks in nfvPPA potentially affects access to compensatory mechanisms involving right hemisphere homologues. Measures of silences during reading also discriminated the PPA and control groups, but did not increase predictive accuracy. Findings suggest that a measure of relative vowel duration from of a polysyllable word repetition task may be sufficient for detecting most cases of apraxia of speech and distinguishing between nfvPPA and lvPPA

Single word intelligibility in aphasia and apraxia of speech

Single word speech intelligibility was evaluated in three groups: aphasia with apraxia of speech, aphasia with no apraxia of speech, and normal controls. Intelligibility was significantly lower in the two aphasic groups compared with the normal group and intelligibility did not differ significantly between the aphasia and apraxia of speech and the aphasia only groups. Seventy per cent of the speakers with apraxia of speech obtained intelligibility scores below the normal range and 80 % of the speakers with aphasia only obtained intelligibility scores within the normal range. There was a moderate, but statistically nonsignificant, correlation between intelligibility and severity of apraxia of speech on an eight- point rating scale

Apraxia of Speech: Perceptual Analysis of Trisyllabic Words Across Repeated Sampling Occasions

Apraxia of Speech: Perceptual Analysis of Trisyllabic Words Across Repeated Sampling Occasion

Self-Administered Computer Therapy for Apraxia of Speech

Background and Purpose There is currently little evidence on effective interventions for poststroke apraxia of speech. We report outcomes of a trial of self-administered computer therapy for apraxia of speech. Methods Effects of speech intervention on naming and repetition of treated and untreated words were compared with those of a visuospatial sham program. The study used a parallel-group, 2-period, crossover design, with participants receiving 2 interventions. Fifty participants with chronic and stable apraxia of speech were randomly allocated to 1 of 2 order conditions: speech-first condition versus sham-first condition. Period 1 design was equivalent to a randomized controlled trial. We report results for this period and profile the effect of the period 2 crossover. Results Period 1 results revealed significant improvement in naming and repetition only in the speech-first group. The sham-first group displayed improvement in speech production after speech intervention in period 2. Significant improvement of treated words was found in both naming and repetition, with little generalization to structurally similar and dissimilar untreated words. Speech gains were largely maintained after withdrawal of intervention. There was a significant relationship between treatment dose and response. However, average self-administered dose was modest for both groups. Future software design would benefit from incorporation of social and gaming components to boost motivation. Conclusions Single-word production can be improved in chronic apraxia of speech with behavioral intervention. Self-administered computerized therapy is a promising method for delivering high-intensity speech/language rehabilitation

Motor Performance in Children with Childhood Apraxia of Speech and Speech Sound Disorders

Purpose: This study sought to determine if (a) children with childhood apraxia of speech (CAS), other speech sound disorders (SSDs), and typical development (TD) would perform differently on a standardized motor assessment and (b) whether comorbid language impairment would impact group differences. Method: Speech, language, and motor abilities were assessed in children with CAS (n = 10), SSD (n = 16), and TD (n = 14) between the ages of 43 and 105 months. Motor skills were evaluated using the Movement Assessment Battery for Children-Second Edition (Henderson, Sugden, & Barnett, 2007), a behavioral assessment that is sensitive in identifying fine/gross motor impairments in children with a range of motor and learning abilities. Data were reanalyzed after reclassifying children by language ability. Results: The CAS group performed below the normal limit on all components of the motor assessment and more poorly than the TD and SSD groups on Aiming and Catching and Balance. When children were reclassified by language ability, the comorbid CAS + language impairment group performed worse than the SSD-only and TD groups on Manual Dexterity and Balance and worse than the TD group on Aiming and Catching; all 7 children with CAS + language impairment evidenced performance in the disordered range compared to 1 of 3 children in the CAS-only group and 2 of 6 children in the SSD + language impairment group. Conclusions: Children with CAS + language impairment appear to be at an increased risk for motor impairments, which may negatively impact social, academic, and vocational outcomes; referrals for motor screenings/assessments should be considered. Findings may suggest a higher order deficit that mediates cognitive-linguistic and motor impairments in this population

Feedforward and feedback control in apraxia of speech: effects of noise masking on vowel production

PURPOSE: This study was designed to test two hypotheses about apraxia of speech (AOS) derived from the Directions Into Velocities of Articulators (DIVA) model (Guenther et al., 2006): the feedforward system deficit hypothesis and the feedback system deficit hypothesis. METHOD: The authors used noise masking to minimize auditory feedback during speech. Six speakers with AOS and aphasia, 4 with aphasia without AOS, and 2 groups of speakers without impairment (younger and older adults) participated. Acoustic measures of vowel contrast, variability, and duration were analyzed. RESULTS: Younger, but not older, speakers without impairment showed significantly reduced vowel contrast with noise masking. Relative to older controls, the AOS group showed longer vowel durations overall (regardless of masking condition) and a greater reduction in vowel contrast under masking conditions. There were no significant differences in variability. Three of the 6 speakers with AOS demonstrated the group pattern. Speakers with aphasia without AOS did not differ from controls in contrast, duration, or variability. CONCLUSION: The greater reduction in vowel contrast with masking noise for the AOS group is consistent with the feedforward system deficit hypothesis but not with the feedback system deficit hypothesis; however, effects were small and not present in all individual speakers with AOS. Theoretical implications and alternative interpretations of these findings are discussed.R01 DC002852 - NIDCD NIH HHS; R01 DC007683 - NIDCD NIH HH

Assessing the treatment effects in apraxia of speech: introduction and evaluation of the Modified Diadochokinesis Test

Background: The number of reliable and valid instruments to measure the effects of therapy in apraxia of speech (AoS) is limited. Aims: To evaluate the newly developed Modified Diadochokinesis Test (MDT), which is a task to assess the effects of rate and rhythm therapies for AoS in a multiple baseline across behaviours design. Methods: The consistency, accuracy and fluency of speech of 24 adults with AoS and 12 unaffected speakers matched for age, gender and educational level were assessed using the MDT. The reliability and validity of the instrument were considered and outcomes compared with those obtained with existing tests. Results: The results revealed that MDT had a strong internal consistency. Scores were influenced by syllable structure complexity, while distinctive features of articulation had no measurable effect. The testretest and intra- and inter-rater reliabilities were shown to be adequate, and the discriminant validity was good. For convergent validity different outcomes were found: apart from one correlation, the scores on tests assessing functional communication and AoS correlated significantly with the MDT outcome measures. The spontaneous speech phonology measure of the Aachen Aphasia Test (AAT) correlated significantly with the MDT outcome measures, but no correlations were found for the repetition subtest and the spontaneous speech articulation/prosody measure of the AAT. Conclusions & Implications: The study shows that the MDT has adequate psychometric properties, implying that it can be used to measure changes in speech motor control during treatment for apraxia of speech. The results demonstrate the validity and utility of the instrument as a supplement to speech tasks in assessing speech improvement aimed at the level of planning and programming of speech

Characterizing a neurodegenerative syndrome: primary progressive apraxia of speech

Apraxia of speech is a disorder of speech motor planning and/or programming that is distinguishable from aphasia and dysarthria. It most commonly results from vascular insults but can occur in degenerative diseases where it has typically been subsumed under aphasia, or it occurs in the context of more widespread neurodegeneration. The aim of this study was to determine whether apraxia of speech can present as an isolated sign of neurodegenerative disease. Between July 2010 and July 2011, 37 subjects with a neurodegenerative speech and language disorder were prospectively recruited and underwent detailed speech and language, neurological, neuropsychological and neuroimaging testing. The neuroimaging battery included 3.0 tesla volumetric head magnetic resonance imaging, [18F]-fluorodeoxyglucose and [11C] Pittsburg compound B positron emission tomography scanning. Twelve subjects were identified as having apraxia of speech without any signs of aphasia based on a comprehensive battery of language tests; hence, none met criteria for primary progressive aphasia. These subjects with primary progressive apraxia of speech included eight females and four males, with a mean age of onset of 73 years (range: 49–82). There were no specific additional shared patterns of neurological or neuropsychological impairment in the subjects with primary progressive apraxia of speech, but there was individual variability. Some subjects, for example, had mild features of behavioural change, executive dysfunction, limb apraxia or Parkinsonism. Voxel-based morphometry of grey matter revealed focal atrophy of superior lateral premotor cortex and supplementary motor area. Voxel-based morphometry of white matter showed volume loss in these same regions but with extension of loss involving the inferior premotor cortex and body of the corpus callosum. These same areas of white matter loss were observed with diffusion tensor imaging analysis, which also demonstrated reduced fractional anisotropy and increased mean diffusivity of the superior longitudinal fasciculus, particularly the premotor components. Statistical parametric mapping of the [18F]-fluorodeoxyglucose positron emission tomography scans revealed focal hypometabolism of superior lateral premotor cortex and supplementary motor area, although there was some variability across subjects noted with CortexID analysis. [11C]-Pittsburg compound B positron emission tomography binding was increased in only one of the 12 subjects, although it was unclear whether the increase was actually related to the primary progressive apraxia of speech. A syndrome characterized by progressive pure apraxia of speech clearly exists, with a neuroanatomic correlate of superior lateral premotor and supplementary motor atrophy, making this syndrome distinct from primary progressive aphasia

Communicative participation improves following motor speech program treatment in apraxia of speech

Childhood apraxia of speech (CAS) is a motor speech disorder characterized by increase in segment and intersegment durations (segmentation), equal stress over words and/or sentences, dysprosody, and speech sound distortions. With decreased intelligibility, limited or lack communicative participation arises from an inability to be understood or lack of confidence in their speech. Establishing communicative participation measurements is integral to generalizing and establishing efficacy of treatment program progress to a child’s everyday life. This study observes the communicative participation change of a group of children (n=6) with idiopathic CAS, receiving a new four-week, 16-hour treatment called Treatment for Establishing Motor Programming Organization (TEMPO). Clinically significant changes were seen in communicative participation post TEMPO treatment using the FOCUS-34© parental questionnaire with an average change of 50 points. Specifically, sub-scales of intelligibility, social/play, independence, and coping/emotional skills were seen as driving components of this change

Behavioral, computational, and neuroimaging studies of acquired apraxia of speech

A critical examination of speech motor control depends on an in-depth understanding of network connectivity associated with Brodmann areas 44 and 45 and surrounding cortices. Damage to these areas has been associated with two conditions-the speech motor programming disorder apraxia of speech (AOS) and the linguistic/grammatical disorder of Broca's aphasia. Here we focus on AOS, which is most commonly associated with damage to posterior Broca's area (BA) and adjacent cortex. We provide an overview of our own studies into the nature of AOS, including behavioral and neuroimaging methods, to explore components of the speech motor network that are associated with normal and disordered speech motor programming in AOS. Behavioral, neuroimaging, and computational modeling studies are indicating that AOS is associated with impairment in learning feedforward models and/or implementing feedback mechanisms and with the functional contribution of BA6. While functional connectivity methods are not yet routinely applied to the study of AOS, we highlight the need for focusing on the functional impact of localized lesions throughout the speech network, as well as larger scale comparative studies to distinguish the unique behavioral and neurological signature of AOS. By coupling these methods with neural network models, we have a powerful set of tools to improve our understanding of the neural mechanisms that underlie AOS, and speech production generally