Kinematic investigation of tongue movement in Parkinson’s disease

Abstract

Articulatory dysfunction is recognized as a major contributor to the speech disturbances in people with Parkinson’s disease (PD). Although dysarthria in PD has been widely studied, however, majority of the studies have been based on perceptual and acoustic analyses. Only a limited number of studies have utilized objective kinematic investigation to examine tongue function during speech production in this population. This study aimed to investigate tongue kinematics during sentence production and rapid syllable repetition in dysarthric and non-dysarthric speakers with idiopathic PD using electromagnetic articulography (AG-200 EMA). A group of neurologically healthy individuals matched for age and gender served as controls. The tongue tip and tongue back movements of all participants during alveolar and velar sentence production, and rapid /ta/ and /ka/ syllables repetition were recorded using EMA. Perceptual results showed that the participants with dysarthria were mildly dysarthric. Kinematic results of the present study suggest the presence of impaired tongue control in both dysarthric and non-dysarthric speakers with PD. During sentence production, comparison with healthy controls showed that both dysarthric and non-dysarthric groups had deviant articulatory movement resulted in longer duration of consonant production. When compared to the non-dysarthric speakers, the dysarthric speakers primarily had increased range of tongue movement together with increased speed measures of tongue movement that resulted in comparable duration of lingual movement. During rapid syllable repetition, the kinematic results revealed significant between-group differences for most of the kinematic parameters measured but comparable rapid syllable repetition rates. Subsequent case analyses also revealed marked individual differences. Clinical implications of the study were discussed.