Ultrasonographic Assessment of Oral-Phase Swallowing Function in Parkinson’s disease

Background Dysphagia (swallowing difficulty) is commonly observed in patients with Parkinson’s disease (PwPDs) and significantly impairs their quality of life. Although ultrasonography is a non-invasive and easily applicable method that allows real-time evaluation of functional structure, evidence on its utility for the assessment swallowing function in PwPDs remains limited. This study aimed to investigate oral-phase swallowing function in PwPDs using ultrasonography. Methods Twenty-two PwPDs (mean age 69.2 ± 9.1 years) were recruited and divided into two groups based on the presence or absence of dysphagia. Additionally, 24 younger healthy participants (mean age 30.8 ± 8.5 years) were enrolled as a reference group. Swallowing function was assessed using ultrasonography across six parameters: resting geniohyoid muscle (GM) thickness, resting GM cross-sectional area, swallowing time, number of contractions, and velocity at first contraction (upper and lower). Results Compared to PwPDs without dysphagia (PDD-), those with dysphagia (PDD+) exhibited significantly prolonged swallowing time (PDD-: 1.66 ± 0.62 s vs. PDD+: 3.65 ± 2.94 seconds, p = 0.017), while no differences were observed in other parameters. Spearman’s correlation analysis revealed that tongue pressure correlated with the resting GM thickness, resting GM cross-sectional area, swallowing time, and number of contractions. Multivariable linear regression identified the number of contractions as a significant predictor of swallowing time ( β = 0.950; p < 0.001). The area under the receiver operating characteristic curve for swallowing time was 0.800 (95% confidence interval, 0.593–1.00). A cut-off value of 2.2 s based on the Youden index yielded optimal sensitivity and specificity of 0.700 and 0.833, respectively. Conclusions This study demonstrated that the swallowing time measured using ultrasonography can serve as a useful screening marker for evaluating oral-phase swallowing dysfunction in PwPDs. Further research is warranted to explore the clinical implications of these findings.