Abstract
Objectives: To improve understanding of the physical characteristics of patients with obstructive sleep apnea （OSA） by measuring muscle stiffness in the submental region in both patients with OSA and healthy participants as a normal control.
Methods: In total, 16 participants with OSA （8 men and 8 women, 51.8 years） and 14 healthy participants （7 men and 7 women, 50.1 years） were recruited. Submental muscle stiffness was measured at the habitual occlusal position （HOP）, maximum mandibular protrusive position （MPP）, and tongue protrusive position （TPP） during breathing cessation. A muscle hardness meter was used for the measurements.
Results: The HOP was significantly lower than the MPP and TPP in both groups （p＜0.05）. While similar tendencies were observed in women across the groups, in males, the HOP was significantly lower than the MPP in the control group and lower than the TPP in the OSA group. Interestingly, there was a tendency for muscle stiffness in each jaw position to be higher in women than men between the two groups. A significant negative correlation between TPP/HOP and apnea hypopnea index （AHI） was observed.
Conclusion: There was no significant difference for the muscle stiffness in each jaw position between the OSA group and the control group, and there was also no significant difference for the muscle stiffness in each jaw position between women and men. Furthermore, there was a significant negative correlation between TPP/HOP and AHI. These findings suggest that the muscle stiffness test may be useful in the examination of OSA.
