Ross Hauser, MD, Danielle Matias, PA-C, Demi Foster, APRN
Most people recognize the more familiar BOTOX® brand name for Botulinum toxin injection. Most are also familiar that these injections give a more youthful facial appearance by relaxing muscles and thereby reducing wrinkles. This concept of relaxing muscles is the basis behind botulinum toxin injection as an alternative treatment for TMJ and related jaw pain. The treatment is injected into the muscles of the face and jaw where spasm causes pain and discomfort.
Myofascial pain syndrome is a common painful muscle disorder caused by taut bands or trigger points in the muscles including the muscles of the TMJ. Myofascial trigger points are tender areas in muscles causing local and referred muscle pain. Trigger points may cause tight muscles and tight muscles may cause trigger points. That is not a play on words, that is actually what can happen, you have spasms because of instability in the jaw. Those continuous spasms can cause points of pain sensitivity within the muscle from “over-spasming.”
A November 2021 paper in The Journal of Craniofacial Surgery (1) analyzed the clinical outcome of botulinum toxin type A intramuscular injections into the head and neck, particularly the masticatory muscles of patients with temporomandibular disorder (TMD).
- A total of 68 patients had received botulinum toxin type A intramuscular injections for TMD symptoms.
- Overall, 87% of them reported favorable outcomes. 8 (13%) reported BOTOX® injections as not beneficial, 15 (24%) as beneficial, and 40 patients (63%) as highly beneficial.
- Most patients had already received conventional treatment with an occlusal splint (93%) combined with pain medication (60%) in the primary care units before BOTOX® treatments.
- There were 59 (83%) female patients, and they responded better to BOTOX® therapy than the male patients: 91% versus 57%.
A December 2020 paper in the Journal of Oral Science (2) listed improvements however as temporary. In this paper, twenty-two patients who received a diagnosis of chronic masseter and temporalis myofascial pain were evaluated by using a visual analog pain scale (no pain is a zero score – unbearable pain is a score of 10), among other disability and pain scoring surveys. The outcome was that while at two months after botulinum toxin treatment the patients showed significant improvement in quality of life, those improvements did not hold at seven months. However, the researchers concluded that botulinum toxin type A injections resulted in safe, effective short-term pain relief for patients with chronic facial pain affecting the masseter and temporalis muscles.
A June 2020 paper published in The British Journal of Oral & Maxillofacial Surgery (3) also found good but short-term benefits. The researchers wrote: “Despite showing benefits, consensus on the therapeutic benefit of botulinum toxin in the management of myofascial temporomandibular joint disorders is lacking. Further randomized controlled trials with larger sample sizes, minimal bias, and longer follow-up periods are now needed.”
In September 2023 researchers writing in the Journal of Stomatology, Oral and Maxillofacial Surgery (4) provided an updated assessment of the effectiveness of myogenic (muscle-related) botulinum toxin injection and provided a before and after comparison. In this paper of 45 patients who received botulinum toxin injections in the temporalis and masseter muscles, the researchers found significant improvement in pain, function, and quality of life.
An October 2023 study in the medical journal Toxins (5) aimed to evaluate the efficacy of botulinum toxin type A in patients with temporomandibular disorders (TMDs) associated with masticatory muscle pain and headaches.
- Twenty-one patients with myogenous (masticatory muscle) TMD were randomly assigned to two groups.
- The experimental and control groups received injections of either botulinum toxin type A or saline into the sites showing tenderness after palpation of a total of 16 muscle areas, including each masseter, a temporalis, splenius capitis, sternocleidomastoid, and trapezius muscle.
- During each visit, the clinical effects, based on the intensity of orofacial pain, headache, number of tender points, maximum mouth opening, and headache frequency, were evaluated at pre-injection and 4, 8, and 12 weeks after the injection, in both groups.
- In the botulinum toxin type A group, the positive reductions in orofacial pain, number of tender points, headache, and headache frequency showed significant differences over time. There were no positive findings of benefit for maximum mouth-opening.
In research from May 2024 (6) in the Journal of Oral Rehabilitation, researchers from McGill University analyzed data from 15 studies and 504 participants in finding botulinum toxin type A was significantly more effective than placebo in reducing pain intensity, as measured on a 0-10 scale, at 1 month and 6 months. A higher dosage of botulinum toxin type A (60-100 U bilaterally) was associated with a greater reduction in pain at 6 months.
A July 2024 study in the journal Cranio (7) evaluated the effectiveness of low dose botulinum toxin type A for pain management in patients with sleep bruxism, awake bruxism, and temporomandibular disorder (TMD).
- Thirty-five patients diagnosed with chronic TMD pain, sleep bruxism, and awake bruxism were injected with a single dose of 20 U of botulinum toxin type A in the masseter and temporalis muscles. Pain improvement was measured via patient reported 0 – 10 pain scores using the visual analog scale (VAS) before and after 15, 30, 60, 90, and 180 days of the injection.
The patients reported decrease in pain after 15 days of treatment. The maximum pain relief persisted for up to 90 days after botulinum toxin type A application in patients with sleep bruxism and awake bruxism and 15 days for patients with TMD. The researchers concluded: “A low dose of botulinum toxin type A may be effective for controlling chronic pain related to sleep bruxism and awake bruxism, but TMD pain reduction was short-lived.”
Arthrocentesis and Hyaluronic acid with Botox
In November 2023 doctors published their findings of a 3-year prospective study in the Journal of Cranio-Maxillo-Facial Surgery. (8) In this study, the effectiveness of temporomandibular joint (TMJ) arthrocentesis with viscosupplementation was evaluated in patients with Dimitroulis (severity) classification categories 2-4. TMJ arthrocentesis was performed with Incobotulinum toxin A administered 10-15 days prior in patients with concomitant masticatory myalgia.
- A total of 108 patients were enrolled; 86 (80%) were women and 22 (20%) were men.
- The overall successful outcome of TMJ arthrocentesis with viscosupplementation was 76%.
- The authors observed increased arthrocentesis effectiveness and success rate with viscosupplementation in Dimitroulis category 2 (88.6%) compared to 3-4 (71.4%).
- An association was found between arthrocentesis with viscosupplementation failure and painful myalgia.
- Thirteen patients (12%) underwent a second TMJ intervention after finalizing the present trial.
The researchers concluded: “With a low complication rate, TMJ arthrocentesis with viscosupplementation led to an overall benefit for all the included patients. This study reinforces the important role of minimally invasive TMJ arthrocentesis as a first treatment option, with better results in the early stages compared to more severe stages.”
Botulinum toxin and jaw bone degeneration?
A February 2020 (9) study in the journal Scientific Reports addressed the controversy surrounding masticatory muscle atrophy induced by botulinum toxin injection. The controversy exists because it cannot be shown (definitely) if botulinum toxin injection causes enough muscle atrophy to create more instability in the jaw and an eventual bone-on-bone grinding of the jaw bone and the mandible. In this study, a group of 39 women (average age about 27) and 38 post-menopausal women (average age about 55) had an application of a stabilization splint, and/or two times botulinum toxin injection in the bilateral temporalis and masseter muscles within a six-month treatment period. It was observed in the patients a decreased masticatory muscle thickness (atrophy of the muscle), especially in post-menopausal females. The botulinum toxin injection may induce muscle atrophy that damages the jaw bone by way of joint instability.
More reading
Our published research
The association between mandibular position to cervical spine and internal jugular vein diameters in upright position. Have we been ignoring critical generators of head and neck pathology? Lockerman LZ, Hauser R. The association between mandibular position to cervical spine and internal jugular vein diameters in upright position. Have we been ignoring critical generators of head and neck pathology? Cranio. 2023 Sep;41(5):403-406. [Google Scholar]
Dextrose Prolotherapy and Pain of Chronic TMJ Dysfunction Hauser R., Hauser H, Blakemore KA. Dextrose Prolotherapy and Pain of Chronic TMJ Dysfunction. (2007) [Google Scholar]
References
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