Objective: To describe acoustic features of speech in Primary Generalized Dystonia (PGD) in order to identify potential subtypes of dysarthria, in line with the previous perceptual description provided by Darley et al., (1969).

Background: PGD is a neurologic disorder often associated with a hyperkinetic dysarthria. The seminal classification of dysarthria made by Darley et al., (1969) denotes that the deterioration of speech in dystonic patients results from a phonatory stenosis, an articulatory inaccuracy, and a prosodic excess or/and insufficiency. An important respiratory dysrhythmia also contributes to the degradation of intelligibility (Lablance & Rutheford, 1991).

Methods: Eleven patients with PGD and 11 gender- and age-matched healthy volunteers were recruited. They were instructed to perform 6 speech production tasks to assess phonation quality, articulatory coordination, speech temporal organization (prosodic excess and insufficiency) and speech intelligibility. A motor assessment using the Burke-Fahn-Marsden scale was also performed (mean = 42,61; standard deviation = +/- 24,88).

Results: Significant differences were found between PGD patients and controls: patient with PGD demonstrated a much higher laryngeal instability, a reduction of speech loudness and a shortenening of maximal phonation time. The analysis-by-subject demonstrated that 4 patients among the 11 studied presented with at least one temporal variable altered.

Conclusions: All patients with PGD revealed a common and important “phonatory stenosis” manifested by difficulties in pneumo-phonic coordination and laryngeal instability. Due to the important inter-individual heterogeneity in PGD, the individual objective analysis of speech was necessary and accordingly, among our patients, 4 were identified to suffer from “prosodic excess”, a dysrhythmia altering speech temporal organization. While dysarthria is considered as a motor speech disorder, it is much needed to explore the contribution of non-motor dysfunctions to further describe dysfunctions of speech temporal organization.

References: Darley, F. L., Aronson, A. E., & Brown, J. R. (1969, b). Differential diagnostic patterns of dysarthria. Journal of Speech and Hearing Research, 12(2), 246–269. http://doi.org/10.1044/jshr.1202.246. LaBlance, G. R., & Rutherford, D. R. (1991). Respiratory dynamics and speech intelligibility in speakers with generalized dystonia. Journal of Communication Disorders, 24(2), 141–156. https://doi.org/10.1016/0021-9924(91)90018-E.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/acoustical-characteristics-of-speech-impairment-in-primary-generalized-dystonia/