Treatment of myofascial pain and dysfunction using botulinum toxin A: a prospective study

Abstract

Abstract Purpose We prospectively assessed the effects of botulinum toxin type-A (BTX-A) on primary and secondary outcomes in a population of refractory myofascial pain and dysfunction patients when conservative management had proven ineffective. Methods In this study, 26 patients with masticatory myofascial pain, who were refractory to conservative management, were enrolled prospectively to evaluate responses following the injection of botulinum toxin-A (BTX-A). Masseter muscles were injected with 30 units BTX-A and 20 units into the temporalis muscles. Pain, tenderness to palpation, and oral function were evaluated subjectively using a visual analog scale (VAS). Objective outcomes of maximal mouth opening (MMO) and reduction in total facial width after injection with BTX-A were measured. Participants were reassessed at 1-week, 1, 3, and 6-month intervals. A linear mixed-effect model was employed to assess the level of correlation (dependence) among different outcomes. Results Administration of BTX-A had a significant strong positive correlation with the reduction of pain (Phi = 0.641, P < 0.0005); significant strong positive correlation with increase in oral function (Phi = 0.738, P < 0.0015); significant strong positive correlation with increase in maximal mouth opening (Phi = 0.645, P < 0.0085); significant strong positive correlation with tenderness to palpation (Phi = 0.510, P < 0.0011); and significant strong positive correlation with reduction in facial width (Phi = 0.565, P < 0.0001). Conclusion The results from this study demonstrate that BTX-A administration may provide a safe and effective means to treat myofascial pain from hyperfunctioning masticatory muscles. It is not recommended to replace first-line treatment but may provide relief from chronic facial pain if properly administered in patients where standard conservative management has been unsuccessful.