Does Adjunctive Botulinum Toxin A Reduce Pain Scores When Combined With Temporomandibular Joint Arthroscopy for the Treatment of Concomitant Temporomandibular Joint Arthralgia and Myofascial Pain?

Abstract

Currently, there is no standard of care for the treatment of refractory myofascial pain and concomitant temporomandibular joint (TMJ) arthralgia. This comparative study was conducted to determine the effectiveness of botulinum toxin A (Btx), as an adjunct to TMJ arthroscopy, in this patient population. A retrospective cohort study was conducted of patients who underwent TMJarthroscopy with (Btx group) or without (control group) intramuscular Btx for TMJ arthritis and refractory myofascial pain at the University of Michigan (Ann Arbor) from 2011 through 2014. For patients in the Btx group, intramuscular injections of Btx were administered at sites of maximal tenderness within the masseter and temporalis muscles. The primary outcome variable was pain score on the visual analog scale (VAS; 0 to 10). The secondary outcome variables included maximal interincisal opening, total score for sites of tenderness, total number of tender sites, and diet consistency tolerated. Statistical analysis included means and standard deviations, Student t test, simple regression analysis, and multiple regression analysis. The study cohort included 52 patients (30 in Btx group, 22 in control group), of which 48 (92.3%) were women. The mean follow-up was 5.56±1.41months. Patients in the Btx group had a significantly greater decrease in mean pain score (P=.04) on the VAS compared with the control group (score, 3.24 for Btx group; score, 1.13 for control group). On multivariate regression analysis, treatment with Btx trended toward significance (P=.084) and the preoperative pain score (P=.0007) was significantly correlated with the change in pain observed. The use of Btx appears to correlate with a clinically superior decrease in pain score compared with the control group. The use of Btx could be useful as an adjunctive treatment modality in the management of refractory myofascial pain.