Brain Sciences (Jan 2023)

Speech and Nonspeech Parameters in the Clinical Assessment of Dysarthria: A Dimensional Analysis

  • Wolfram Ziegler,
  • Theresa Schölderle,
  • Bettina Brendel,
  • Verena Risch,
  • Stefanie Felber,
  • Katharina Ott,
  • Georg Goldenberg,
  • Mathias Vogel,
  • Kai Bötzel,
  • Lena Zettl,
  • Stefan Lorenzl,
  • Renée Lampe,
  • Katrin Strecker,
  • Matthis Synofzik,
  • Tobias Lindig,
  • Hermann Ackermann,
  • Anja Staiger

DOI
https://doi.org/10.3390/brainsci13010113
Journal volume & issue
Vol. 13, no. 1
p. 113

Abstract

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Nonspeech (or paraspeech) parameters are widely used in clinical assessment of speech impairment in persons with dysarthria (PWD). Virtually every standard clinical instrument used in dysarthria diagnostics includes nonspeech parameters, often in considerable numbers. While theoretical considerations have challenged the validity of these measures as markers of speech impairment, only a few studies have directly examined their relationship to speech parameters on a broader scale. This study was designed to investigate how nonspeech parameters commonly used in clinical dysarthria assessment relate to speech characteristics of dysarthria in individuals with movement disorders. Maximum syllable repetition rates, accuracies, and rates of isolated and repetitive nonspeech oral–facial movements and maximum phonation times were compared with auditory–perceptual and acoustic speech parameters. Overall, 23 diagnostic parameters were assessed in a sample of 130 patients with movement disorders of six etiologies. Each variable was standardized for its distribution and for age and sex effects in 130 neurotypical speakers. Exploratory Graph Analysis (EGA) and Confirmatory Factor Analysis (CFA) were used to examine the factor structure underlying the diagnostic parameters. In the first analysis, we tested the hypothesis that nonspeech parameters combine with speech parameters within diagnostic dimensions representing domain–general motor control principles. In a second analysis, we tested the more specific hypotheses that diagnostic parameters split along effector (lip vs. tongue) or functional (speed vs. accuracy) rather than task boundaries. Our findings contradict the view that nonspeech parameters currently used in dysarthria diagnostics are congruent with diagnostic measures of speech characteristics in PWD.

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