Patient-Reported Outcome Measures After Botulinum Toxin for Temporomandibular-Related Myalgia: A Prospective Study

Introduction: Botulinum toxin-A (BTX-A) injections are regularly used to treat temporomandibular disorders (TMD). However, consensus regarding the long-term efficacy of BTX-A for TMD-related myalgia remains lacking. This pragmatic, practice-based clinical study aimed to evaluate the Patient-Reported Outcome Measures of pain, health status, quality of life, and function after BTX-A injections in patients with TMD-related myalgia. Methods: This prospective cohort study included 35 patients with TMD-related myalgia who received BTX-A injections in the masseter and temporalis muscles. The Visual Analogue Scale for pain, the EQ-5D-3L for health status, the Oral Health Impact Profile-14 for oral health-related quality of life, the Mandibular Function Impairment Questionnaire for function and the maximum interincisal opening were assessed before treatment and at one, three and six months follow-up. Results: Patients reported a statistically significant and clinically relevant reduction in pain (p < 0.001), improvement of health status (p ≤ 0.003), and oral health-related quality of life (p < 0.001) at one-month follow-up, which remained present at three and six months post-treatment. Self-reported mandibular function and active and passive mouth opening showed no significant change over all time points. Conclusions: In this pragmatic cohort, BTX-A injections in the masseter and temporalis muscles seem to improve pain and oral health-related quality of life in patients with TMD-related myalgia within one month and show effects lasting up to six months, while mandibular function did not improve.