Article

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.

Langue : ANGLAIS