J Orofac Pain 32 (2018), No. 3 9. Aug. 2018
J Orofac Pain 32 (2018), No. 3 (09.08.2018)
Immediate Effect of Continuous Ultrasound vs Sham Ultrasound for Bilateral Masseter Myalgia: A Double-Blinded Trial
Hussain, Haseeb / Crow, Heidi / Gonzalez, Yoly / McCall jr., W. D.
Aims: To investigate the local and segmental effects of therapeutic ultrasound at a dose of 0.4 w/cm2 with 100% duty cycle for 5 minutes compared to the effect of sham ultrasound on painful masticatory muscles.
Methods: A total of 20 adult female subjects with bilateral masseter myalgia diagnosed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were included. Each subject was randomized to either an active ultrasound group or a sham ultrasound group. The intervention was applied to each masseter muscle for 5 minutes. Measures included pre- and post-self-reported pain intensity recorded on a verbal rating scale (VRS), pressure pain thresholds for the masseter (PPT-M) and temporalis (PPT-T) muscles, and intraoral temperature for the masseter muscle. Preintervention score was subtracted from the postintervention score for all measures to calculate mean change in pain, and nonparametric Mann-Whitney test was used to compare the groups. Statistical significance was set at P < .05.
Results: Changes in VRS did not show a significant difference between groups (P > .05). There were significant increases in PPT-M and intraoral temperature in the ultrasound group compared to the sham group (P < .05). There was no significant difference in PPT-T (P > .05), suggesting no segmental effect.
Conclusion: Therapeutic ultrasound produced an immediate increase in PPT-M and intraoral temperature compared to sham ultrasound in female subjects with bilateral masseter myalgia.
Keywords: myalgia, TMD, ultrasound