Treatment of Temporo-Myofascial Disorder of Muscular Origin Using Botulinum Toxin: A Prospective Study

Introduction Temporomandibular disorders (TMD) are a group of conditions involving the temporomandibular joint (TMJ), masticatory muscles and associated structures. This broad complex of functional disorders often affects the face and jaws causing chronic pain, earaches, headaches, migraines, neck pain, and dysfunction in many people 1,2,3,4,5,6. Conservative treatment for TMD is similar to that of other musculoskeletal conditions. Pharmacologic therapy includes the use of anti-inflammatory medications, muscle relaxants, or opioid analgesics7,8,9,10. Physical treatments comprise of dental splints, directed physiotherapy, moist heat therapy, soft diet, massage and acupuncture11,12,13,14,15,16,17,18,19,20,21,22,23,24,25. At the extreme end of the spectrum, surgical management includes arthrocentesis, arthroscopy and open joint procedures26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44. Some patients can find relief with a combination of these previously mentioned interventions; however, none of these have been proven to be consistently effective. Open joint procedures are not reversible while anti-inflammatory medications and narcotics can have undesirable side effects on the gastrointestinal and central nervous system, respectively. Furthermore, many patients suffering from severe chronic pain do not feel relief with even the strongest narcotic analgesics45,46.

TMD has a complex etiology consisting of components from internal derangement of the joint, arthralgia and/or a component of myofascial pain and muscle hyperactivity1,2,3,4. A treatment that has high specificity and low side effects directed solely at the muscular aspect, which presents with signs and symptoms of trigger points, clenching, and bruxism, could produce another avenue of intervention with significant potential. Recently, the use of botulinum toxin has proven effective and has the potential to be such an agent for treatment with patients suffering from TMD and other orofacial pain conditions47,48,49,50,51,52,53,54,55.

Botulinum toxins are exotoxins derived from Clostridium botulinum, a gram-positive, anaerobic, spore-forming organism. There are 8 different subtypes; type A (BTX-A) has been used in recent studies for the treatment of motor disorders such as cervical dystonia or the hyperactive muscular component of TMD53,54,55. The specific method of action of botulinum toxin is on peripheral synapses. In the synaptic cleft, the botulinum toxin is brought into the presynaptic cell by endocytosis. It acts by blocking the calcium induced release of acetylcholine by selective proteolysis of synaptomal-associated proteins (SNAP)47,48,4,50,51,52,53,54,55. Inhibition of acytelcholine thus causes an inhibition of muscular hyperactivity.

Botulinum toxin has a number of indications approved by the Food and Drug Administration such as the therapeutic treatment for cervical dystonia, cosmetic use such as glabellar lines and wide spectrum of off-label uses such as extracervical spasticities, cerebral palsy, post stroke spasticity, neurologic, dermatologic, and gastrointestinal disorders56. Off-label use of a licensed drug or biologic product occurs with a wide range of products57,58,59.

Objective of the Study We aim to treat TMD of muscular origin using Botulinum toxin injections in the trigger points.