Evidence for a Motor Performance Deficit Versus a Misapplied Rule System in the Temporal Organization of Utterances in Apraxia of Speech

TB

Progressive Apraxia of Speech: Might There Be Subtypes?

This study examined speech and language characteristics of three groups of individuals with neurodegenerative disease: (1) primary progressive apraxia of speech (AOS) without aphasia (N=18), (2) agrammatic primary progressive aphasia (agPPA) less severe than AOS (N=10), and (3) agPPA more severe than AOS (N=9). Findings indicate that differences in the predominant characteristics of AOS (predominance of articulatory versus prosodic abnormalities) distributed differently among the three groups, independent of AOS severity. Neuroimaging findings also differed among the groups. Results suggest that neurodegenerative AOS may include perceptually distinguishable subtypes that are related to the presence or absence of aphasia and neuroimaging findings

Analysis of First-Encounter Conversations of Right-Hemisphere-Damaged Adults

TB

Perceptual and instrumental assessments of orofacial muscle tone in dysarthric and normal speakers

Clinical assessment of orofacial muscle tone is of interest for differential diagnosis of the dysarthrias, but standardized procedures and normative data are lacking. In this study, perceptual ratings of tone were compared with instrumental measures of tissue stiffness for facial, lingual, and masticatory muscles in 70 individuals with dysarthria. Perceptual and instrumental tone data were discordant and failed to discriminate between five dysarthria types. These results raised concerns about the validity of Myoton-3 stiffness measures in the orofacial muscles. Therefore, a second study evaluated contracted and relaxed orofacial muscles in 10 neurotypical adults. Results for the cheek, masseter, and lateral tongue surface followed predictions, with significantly higher tissue stiffness during contraction. In contradiction, stiffness measures from the superior surface of the tongue were lower during contraction. Superior-to-inferior tongue thickness was notably increased during contraction. A third study revealed that tissue thickness up to ~10 mm significantly affected Myoton-3 measures. Altered tissue thickness due to neuromuscular conditions like spasticity and atrophy may have undermined the detection of group differences in the original sample of dysarthric speakers. These experiments underscore the challenges of assessing orofacial muscle tone and identify considerations for quantification of tone-related differences across dysarthria groups in future studies

Perceptual and instrumental assessments of orofacial muscle tone in dysarthric and normal speakers

Clinical assessment of orofacial muscle tone is of interest for differential diagnosis of the dysarthrias, but standardized procedures and normative data are lacking. In this study, perceptual ratings of tone were compared with instrumental measures of tissue stiffness for facial, lingual, and masticatory muscles in 70 individuals with dysarthria. Perceptual and instrumental tone data were discordant and failed to discriminate between five dysarthria types. These results raised concerns about the validity of Myoton-3 stiffness measures in the orofacial muscles. Therefore, a second study evaluated contracted and relaxed orofacial muscles in 10 neurotypical adults. Results for the cheek, masseter, and lateral tongue surface followed predictions, with significantly higher tissue stiffness during contraction. In contradiction, stiffness measures from the superior surface of the tongue were lower during contraction. Superior-to-inferior tongue thickness was notably increased during contraction. A third study revealed that tissue thickness up to ~10 mm significantly affected Myoton-3 measures. Altered tissue thickness due to neuromuscular conditions like spasticity and atrophy may have undermined the detection of group differences in the original sample of dysarthric speakers. These experiments underscore the challenges of assessing orofacial muscle tone and identify considerations for quantification of tone-related differences across dysarthria groups in future studies

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

Effects of Syntactic Confusion on Semantic Comprehension in Aphasia

TB

Quantitative and graphic acoustic analysis of phonatory modulations: The modulogram

A method is presented for analyzing phonatory instabilities that occur as modulations of fundamental frequency (f0) and sound pressure level (SPL) on the order of 0.2 to 20 cycles per second. Such long-term phonatory instabilities, including but not limited to traditional notions of tremor, are distinct from cycle-to-cycle perturbation such as jitter or shimmer. For each of the 2 parameters (f0, in Hz, and SPL, in dB), 3 frequency domains are proposed: (a) flutter (10-20 Hz), (b) tremor (2-10 Hz), and (c) wow (0.2-2.0 Hz), yielding 6 types of instability. Analyses were implemented using fast Fourier transforms (FFTs) with domain-specific analysis parameters. Outputs include a graphic display in the form of a set of low-frequency spectrograms (the modulogram ) and quantitative measures of the frequencies, magnitudes, durations, and sinusoidal form of the instabilities. An index of a given instability is developed by combining its duration and average modulation magnitude into a single quantity. Performance of the algorithms was assessed by analyzing test signals with known degrees of modulation, and a range of applications was reviewed to provide a rationale for use of modulograms in phonatory assessment

Long-term phonatory instability in individuals with multiple sclerosis

This paper uses a new approach to describe and quantify the long-term phonatory instability of speakers with MS. Sustained vowel phonations of 20 individuals with a definite diagnosis of multiple sclerosis (MS) and 20 age- and gender-matched individuals with normal speech were recorded. The phonations were f0 and intensity analyzed and subjected to spectral analysis using the Fast Fourier Transform. Three methods for analyzing the instabilities are presented, compared, and related to perceptual judgments: (a) coefficients of variation, (b) magnitude-based analysis of spectral energy, and (c) frequency-based analysis of spectral components. All measures reliably distinguished between individuals with MS and persons with normal speech. A single factor based on a linear discriminant analysis of the frequency-based measures was especially useful in distinguishing these groups. Critical frequency bands of instability, corresponding to wow (1-2 Hz), tremor (around 8 Hz), and flutter (17-18 Hz), distinguished the MS group from those of the control group