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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