Kinematic and correlational analyses on labial and lingual functions during syllable repetitions in Cantonese dysarthric speakers with Parkinson's disease of varying severity using electromagnetic articulography (EMA)

Abstract

Articulatory imprecision in Parkinson patients with hypokinetic dysarthria has been attributed to articulatory undershooting. However, contradictory results in terms of acoustics and instrumental investigation has been reported in the literature throughout the years. The present study aimed to investigate labial and lingual kinematics in dysarthric Cantonese speakers with Parkinson’s disease (PD) of different severity (in terms of dysarthria) during rapid syllable repetitions and compared the measures with that of healthy age-matched controls using a 3-dimensional Electromagnetic Articulography (EMA). Dysarthria severity was also correlated with labial and lingual kinematics. Tongue tip, tongue back, upper and lower lips and jaw motion in five PD and six normal participants during repetitions of /pa/, /ta/ and /ka/ were recorded. Participants were also rated perceptually on their dysarthria severity. When compared to the normal group, the PD group showed reduced velocity in lingual movement and reduced distance travelled and velocity in labial movements. Correlational analysis between dysarthria severity and kinematic data revealed positive correlation for duration of lingual movement. Negative correlation was identified for the velocity and rate of lingual movement, and for distance travelled and velocity of labial movement. The present results supported the hypothesis of articulatory undershooting as a contributing factor of articulatory imprecision in hypokinetic dysarthria, while tongue and lip tremor might also cause such consonant imprecision. Possible differential effect of dopamine deficiency on the different cranial nerves has been hypothesized. Keywords: