Long-Term Effects of a Single Application of Botulinum Toxin Type A in Temporomandibular Myofascial Pain Patients: A Controlled Clinical Trial

Abstract

This study assessed the long-term effects of botulinum toxin type A (BoNT-A) in subjective pain, pain sensibility, and muscle thickness in persistent myofascial temporomandibular-disorder pain (MFP-TMD) patients. Fourteen female subjects with persistent MFP received BoNT-A treatment with different doses (10U-25U for temporalis muscle and 30U-75U for masseter muscle). The treatment was injected bilaterally in the masseter and anterior temporalis muscles in a single session. Clinical measurements included: self-perceived pain (VAS), pain sensibility (PPT), and muscles thickness (ultrasonography). Follow-up occurred 1, 3, 6, and 72 months after treatment for VAS and PPT and 1, 3, and 72 months for ultrasonography. For statistical analysis, the Friedman test with the Bonferroni test for multiple comparisons as a post hoc test was used for non-parametric repeated measures comparisons among the evaluation times. A 5% probability level was considered significant in all tests. VAS values presented a significant decrease throughout the study (p < 0.05). Regarding PPT values, a significant increase was found when comparing baseline data with post-treatment follow-ups (p < 0.05), and even though a significant decrease was found in muscle thickness when baseline values were compared with the 1- and 3-months assessments, no differences were found when compared with the 72 months follow-up (p > 0.05). A single injection of BoNT-A presents long-term effects in reducing pain in persistent MFP-TMD patients, and a reversibility of adverse effects on masticatory-muscle thickness.

Adverse effect of botulinum toxin‐A injections on mandibular bone: A systematic review and meta‐analysis

“…Studies included in this meta‐analysis used highly variable BTX doses (50–250 U/injection in humans and 1–2 U/100 g in animals) and follow‐up times (3–12 months in humans and 2–36 weeks in animals). Repeated injections of BTX are necessary as the muscle paralysis action of BTX, 5 even though it is not yet fully established if repeated injections are needed for BTX‐induced pain relief 48 . In preclinical rat hindlimb study, no difference was found in trabecular bone changes 8 weeks after one and two injections 49 .…”

“…Moreover, it is important to distinguish the neuromuscular effect of BTX from its pain alleviating ability. In a recent clinical study, a single injection of BTX lead to a significant reduction in self‐perceived pain, as measured by visual analog scale and pain pressure threshold, up to 6 years after injection 48 . Thus, detailed dose‐ and time‐dependence of BTX effects on bone and pain needs to be investigated in future preclinical studies.…”

“…Studies included in this meta-analysis used highly variable BTX doses injections are needed for BTX-induced pain relief. 48 In preclinical rat hindlimb study, no difference was found in trabecular bone changes 8 weeks after one and two injections. 49 In rat mandible study, a more significant impact on bone mass was observed after three BTX injections compared to a single injection.…”

“…In a recent clinical study, a single injection of BTX lead to a significant reduction in self-perceived pain, as measured by visual analog scale and pain pressure threshold, up to 6 years after injection. 48 Thus, detailed dose-and time-dependence of BTX effects on bone and pain needs to be investigated in future preclinical studies. Bone remodelling is a slow process, with recommended follow-up every 2 years for bone mineral density in diseases like osteoporosis.…”

Effect of botulinum toxin type A on muscular temporomandibular disorder: A systematic review and meta‐analysis of randomized controlled trials

“…Another review suggested a slight decrease in pain in the BTX-A group after 1 month and emphasized the need for further high quality studies. 5 Recently, several new randomized controlled trials (RCTs) [8][9][10][11][12][13][14][15][16][17] have been published, allowing for a more comprehensive evaluation of the changes in pain intensity, muscle activity and mandibular movement range following BTX-A injection, across different follow-up intervals and injection protocols. This systematic review and meta-analysis of randomized controlled trials aimed to assess the effectiveness, safety and optimal dose of BTX-A for the treatment of muscular TMD.…”