Ultrasonographic characteristics of masseter muscle myalgia: a comparative study

To compare the ultrasonographic characteristics of masseter muscles in temporomandibular disorder (TMD) subjects with a diagnosis of myalgia of the masticatory muscles to a control population.

In total, 45 TMD subjects with masseter muscle myalgia according to the Diagnostic Criteria for Temporomandibular Disorders were compared with 45 control subjects. The masseter muscles of each subject were examined by ultrasonography (US) to assess the quantitative characteristic of local cross-sectional dimension (LCSD) and the qualitative parameters of intramuscular ultrasonographic appearance, anechoic areas, and isoechogenic areas.

Differences in mean LCSD between TMD and control subjects were not statistically significant (P = .565). Similarly, mean LCSD in the unilateral TMD subjects was not significantly different than in the bilateral TMD subjects (P = .808). The type I ultrasonographic appearance, in which fine bands are clearly visible in the muscle, was the most prevalent pattern, detected in 57.2% of muscles. Anechoic areas were present in 16.1% of muscles, and isoechogenic areas were found in 15.6% of muscles, but differences between TMD subjects and control subjects for qualitative ultrasonographic characteristics were not statistically significant (P ≥ .156).

None of the ultrasonographic characteristics were significantly different between TMD subjects and controls. Considering the limitations of the study, future research is required to assess the utility and reliability of US as a diagnostic tool for masticatory muscle myalgia.