Using electromagnetic articulography to investigate tongue, lip and jaw tremor associated with Parkinson's disease.

Tremor in Parkinson's disease is most frequently studied in the limbs, even though it also occurs in the vocal tract. In the current study, we assessed the presence of tongue, lip and jaw tremor in 34 individuals with Parkinson's disease (IwPD) and 25 controls (CS). We used electromagnetic articulography sensors attached to the tongue, the lips, and the jaw to measure orolingual tremor while the participants were performing a series of tasks. Additionally, we acoustically measured frequency and amplitude tremor of the voice in a sustained phonation task. Our findings revealed that IwPD showed significantly more tongue, lip, and jaw tremor than CS. Kinematic tremor frequency and RMS amplitude did not differ between IwPD and CS. We found no group difference in voice tremor prevalence or frequency in our acoustic analysis. While intensity and power indices seemed stronger in IwPD compared to CS, these differences were not significant. We show that electromagnetic articulography is suited for identifying orolingual tremor. While kinematic tremor was more prevalent in IwPD, it also appeared in CS, underlining the importance of including control participants in this type of study.