High-density surface electromyography evaluation of the suprahyoid muscles in patients with Parkinson's disease.

Background And Purpose: High-density surface electromyography (HD-sEMG) allows non-invasive analysis of motor unit (MU) activity and recruitment. This study examines MU recruitment features as well as action potential using HD-sEMG in the suprahyoid muscles of patients with Parkinson's disease (PD) and assesses alterations caused by cervical percutaneous interferential current stimulation.

Methods: Electrical activity of the suprahyoid muscles during tongue elevation was measured using HD-sEMG. Maximum voluntary contraction (MVC) was measured, then the modified entropy, coefficient of variation, correlation coefficient, and root mean square (RMS) were examined. For comparison, HD-sEMG was also conducted on healthy controls. In addition, this study assessed the impact of cervical percutaneous interferential current stimulation on HD-sEMG in patients with PD (Hoehn-Yahr stages 2-4) over 8 weeks.

Results: Twenty-two patients with PD (mean age 71.7 ± 6.0, 7 females) and 14 healthy controls (mean age 74.9 ± 6.1, 7 females) were included. The RMS at 60 % MVC was significantly lower in patients with PD than in healthy controls (p = 0.007). After cervical percutaneous interferential current stimulation, the correlation coefficients at 40 % and 60 % MVC significantly decreased (p = 0.040 and p = 0.048, respectively), and the RMS at 60 % MVC significantly increased (p = 0.035).

Conclusion: HD-sEMG of the suprahyoid muscles showed characteristic findings in patients with PD and was able to detect subtle changes due to electrical stimulation intervention. Thus, HD-sEMG could be a promising tool for evaluating swallowing-related muscle conditions and interventions.