Clinical Evaluation of Botulinum Toxin a in the Management of Temporomandibular Myofascial Pain

Temporomandibular disorders (TMDs) are a group of musculoskeletal and joint issues that affect the temporomandibular joint (TMJ), masticatory muscles, and associated structures. Common patient presentations that can significantly affect quality of life include pain, joint sounds, limited mouth opening, headaches, earaches, and functional impairment (1,2). The multiple causes of TMD, which include parafunctional habits like bruxism, internal derangements, trauma, and myofascial dysfunction, make diagnosis and therapy challenging (3,4).

Physical therapy, occlusal splints, muscle relaxants, and nonsteroidal anti-inflammatory drugs (NSAIDs) remain the primary line of conservative treatment (4). However, some patients with myofascial pain do not react well to conventional therapeutic methods, necessitating other approaches (5). The neurotoxin botulinum toxin type A (BoNT-A) blocks the release of acetylcholine at the neuromuscular junction, resulting in muscle relaxation and temporary chemodenervation (6). Numerous clinical studies have demonstrated that BoNT-A improves jaw function, reduces the intensity of discomfort, and increases maximal interincisal distance in individuals with myofascial TMD (5-7). Even though there is noticeable pain relief, other trials show differing degrees of improvement in mouth opening, therefore the evidence is still inconclusive (6,7).

Given these disagreements, more randomized controlled trials (RCTs) are required to establish consistent treatment recommendations regarding dosage, injection sites, and follow-up schedules. The lack of local data from Pakistan about the use of BoNT-A in TMD therapy emphasizes the need for population-specific evidence.

Objectives:

To evaluate the effectiveness of botulinum toxin type A (BoNT-A) in patients with temporomandibular myofascial pain, by assessing changes in pain intensity and maximal interincisal distance compared with placebo.