Masseter muscle sonographic features as indices for evaluating efficacy of massage treatment

Objective The aim of this study was to clarify the sonographic features of the masseter muscle as indices for judging the efficacy of massage treatment. Study design Fifteen patients with temporomandibular disorder (10 with unilateral and 5 with bilateral muscle pain) underwent massage treatment alternately on the bilateral masseter and temporal muscles with an oral rehabilitation robot. Sonography was performed before and after treatment, and the masseter thickness and existence of anechoic areas were evaluated. Results The thickness on the symptomatic side in the unilateral group significantly decreased after treatment. Anechoic areas were shown in 20 muscles (66.7%) before treatment, and disappeared or were reduced in size in 17 muscles (85.0%) after treatment. The pretreatment thickness was significantly related to visual analog scale (VAS) scores regarding posttreatment muscle pain and massage impression. The existence of anechoic areas was relevant to VAS scores regarding muscle pain. Conclusion Masseter thickness and existence of anechoic areas might be related to the therapeutic efficacy regarding muscle pain.