Focus of the Report: This report focuses on the use of botulinum toxin (BTX) for treatment of pain associated with temporomandibular disorders.

Technology Description: BTX, a neurotoxin produced by the bacterium Clostridium (C.) botulinum, is classified into 8 distinct serologically related neurotoxins: A, B, C1, C2, D, E, F, and G. BTX inhibits the release of the neurotransmitter acetylcholine at the neuromuscular junction and causes muscle paralysis. BTX has been investigated as a treatment for various chronic painful conditions because of its potential to reduce muscle tension and modulate pain receptor activity in the central nervous system. Presently, only 2 serotypes, botulinum type A (BTX-A) and botulinum type B (BTX-B), have formulations approved by the Food and Drug Administration (FDA). The mechanisms of action for BTX-A and BTX-B are similar. BTX-A cleaves the synaptosomal-associated protein of 25 kilodaltons (kDa) (SNAP-25), while BTX-B cleaves vesicle-associated membrane protein (VAMP); both mechanisms inhibit the release of acetylcholine.

BTX for pain associated with TMD typically involves injection of 10 to 75 units of BTX-A into each masseter, temporalis, or pterygoid muscle group.

Controversy: Medical management of TMD typically includes use of non-steroidal anti-inflammatory drugs (NSAIDs), opioids, corticosteroids, muscle relaxants, antidepressants, anticonvulsants, and benzodiazepines; however, significant side effects and lack of effectiveness limits long-term use. Intramuscular BTX injection remains controversial regarding whether it improves symptoms in patients with refractory TMD; questions remain regarding proven clinical effectiveness. Furthermore, BTX has not been cleared for treatment of TMD by the FDA and is considered off-label use.

Key Questions:

  • Is BTX effective in treating the pain and other symptoms associated with TMDs?

  • How does BTX compare with clinical alternatives for TMD?

  • Is BTX safe in treating pain and other symptoms associated with TMD?

  • Have definitive patient selection criteria been identified for BTX as a treatment of pain and symptoms associated with TMD?

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