Botulinum toxin A injections and adverse effects to mimic muscle in TMD myofascial pain treatment: a case report.

Background: Botulinum toxin A is an increasingly used drug in the treatment of temporomandibular disorders and chronic myofascial pain. Although the treatment is safe, and the procedure is fairly simple, adverse effects can occur. In this case report, we discuss a 37 -year-old, Finnish female patient in whom m. Risorius was temporarily paralyzed by botulinum toxin A injections. According to the study protocol the injections were applied bilaterally to the masseter and temporalis muscles. Represented adverse effects of botulinum toxin A injections are rare according to current literature and therefore it is important to bring this matter up especially from an educational point of view.

Case presentation: This case report describes a case of a 37 -year-old, Finnish female patient who participated in a randomized clinical trial of botulinum toxin A in patients suffering from temporomandibular disorders, more detailed myalgia and headache attributed to temporomandibular disorders conducted in Helsinki University. The patient reported pain in the face area every day for the last 6 months (Diagnostic Criteria for Temporomandibular Disorders Axis II survey) before entering the study. She had had a night splint, more detailed a Michigan splint in the upper jaw, for 1 year and 3 months and had tried selfcare instructions, such as massage and movement therapies, as well as physical therapy with moderate success. Treatment modalities provided only temporary relief for the existing problem.

Conclusion: Even though the patient experienced adverse effects (temporary paralysis of the m.Risorius) after the botulinum toxin A injections she also experienced a noticeable reduction in muscle pain and headache attributed to temporomandibular disorders after the injections and after 6 months still reported reduced pain in the head and neck area. (characteristic pain intensity and graded chronic pain scale values were lower than before the study). Although the paper indicates possible positive outcomes of botulinum toxin A injections for patients suffering from myalgia in mastication muscles and temporomandibular disorders associated headache, there are also adverse effects to consider before making any decision on botulinum toxin A injections.