Motor Neurectomy
Motor neurectomy involves identifying the select branches of the motor nerve and perform radiofrequency lysis of the motor nerve itself. This will denervate a portion of the motor nerve and cause a resulting atrophy of the muscle. The area of the muscle that atrophies produce is irregular, and the resulting shape of the muscle is non-cosmetically acceptable.
In these cases, a second procedure to fill in the atrophied area of the muscle with fat tissue or to perform another selective neurectomy is needed, or possibly both. In either case, the result is long lasting , stable, and more desirable than Botox injections.
Diagnoses linked with this treatment includes:
- Masticatory muscle hypertrophy
Related Reading: TMJ Injection Treatments: Lidocaine, Steroids, Hyaluronate & Botox
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Coronoidectomy
Coronoid elongation is a rare problem and, when severe, usually involves a surgical approach to remove the coronoid. Removal of the coronoid process will slightly compromise the function of the temporalis muscle, but assuming the coronoid is hitting the zygoma during opening, shortening it will allow opening. It is critical to start a vigorous stretching program on the day after surgery to prevent adhesions.
Diagnoses linked with this treatment include:
- Elongated coronoid
- Fractures zygomatic arch that cannot be restored and impinges on the coronoid
Related Reading: 4 Mandibular Mobility Disorders
Resection of Neoplasm
In cases where a jaw muscle, bone, or joint neoplasia is identified, the treatment approach is always surgical and depending on the nature of the neoplasm, radiation or chemotherapy.
Diagnoses linked with this treatment include:
- TMJ Osteosarcoma
- Masticatory muscle neoplasia
Stop Causative Medication
There are several drugs that can activate the extrapyramidal system and thus cause an elevation in the muscle tonus of the jaw closing muscles. Examples of these drugs are the amphetamines and amphetamine-like drugs used for ADHD and diet control. In addition, any drugs that raise the level of serotonin can induce an extrapyramidal motor reaction.
The obvious treatment for this problem is to stop the drug, find a substitute drug that does not cause this reaction, or lower the dose to manage the reaction. Another approach to this problem is to take a second drug that counteracts the motor activating effect of the first drug. For example, if a patient is taking a high does of an SSRI drug, this will often cause motor activation in the jaw due to the elevated serotonin levels during sleep. The use of a non-serotonin modulator, that is a muscle relaxant (e.g. caridisprodol), can be used selectively in patients where it is not possible to lower the SSRI dose.
Diagnoses linked with this treatment include:
- Extrapyramical Reaction to medication
- Jaw muscle spasm
Related Reading: How to Diagnose and Treat Oral Motor Disorders
Counter Stimulation Devices
There are several commercially available devices that detect surface EMG levels from the temporalis muscle and deliver either a sound (buzzing) or an electrical shock to the skin where the electrode is located.
An example of a buzzing device is BruxCare, and an example of an electrical shock device is GrindCare. Both are relatively safe methods without complications other than the patient can habituate to the stimulus, and then they stop working. Both methods have been shown to reduce the frequency and duration of the bruxism events in humans. These methods can be used nightly, but they seem to have no long-term suppressive effect on the bruxism. The first line therapy is still an occlusal splint.
Diagnoses linked with this treatment include:
- Bruxism or strong sustained clenching
Related Reading: Appliance-Based and Occlusion-Based Treatments for TMJ
Botulinum Toxin Injections
There are two main treatments for substantial masticatory muscle hypertrophy beyond “no treatment”. First is a temporary treatment (botulinum toxin injections) that has been found to reduce the volume of the masseter muscle by up to 15%. The second and far more effective approach is a motor nerve neurectomy. As for botulinum toxin, injecting about 25-50 units of botulinum toxin –type A (Botox) is a way to reduce (modestly) the volume of the masseter muscle.
This method could help with the temporalis if it is also hypertrophied and the amount of Botox is the same (25-50 units). These injections can be performed up to every three months, but this amount of Botox is quite high, and will undoubtedly cause facial motor weakness and mimic facial paralysis. For this reason alone, and because the reduction in volume is modest, this is not a first line or long-term treatment.
Diagnoses linked with this treatment include:
- Bruxism or strong sustained clenching
- Facial motor tics
- Orofacial dystonia
- Orofacial dyskinesia
- Masticatory muscle hypertrophy
Related Reading: How to Diagnose 7 Maxillary Growth Disorders
Habit Awareness & Avoidance Protocol
A learned behavior like clenching is best managed with increased cognitive awareness of the habit by the patient. Occlusal splints used part-time during the day can be used to help the patient avoid clenching. Another exercise based method for clenching is to use the myofascial stretching program described in the MFP protocol (see TMD treatments).
Diagnoses linked with this treatment include:
- Strong sustained clenching
- Clenching
- Repeated oral habits such as gum chewing and bracing or setting the jaw
- Repeated wide opening habit (usually to clear ear stuffiness)
Related Reading: Closed Lock Mobilization: TMJ Exercises & Stretches
Daily Stretching of Contracted or Fibrosed Jaw Muscles
This stretching protocol is similar to the stretching you do within the myofascial pain protocol or the TMJ mobilization protocol. The difference is that the diagnosis is extracapsular restriction of motion due to muscle, fascial, or cutaneous fibrosis. The stretching, in this case, requires more force. The goal of increased motion is less achievable.
In this case, sometimes the goal is to prevent further limitations. The appropriate diagnoses that would indicate the need for daily stretching of contracted or fibrosed jaw muscles or scars would be limited jaw opening due to contracture of the masticatory muscles or any scaring of the oral mucosal or cutaneous tissues that lead to limited opening or a chronically protrusive jaw position.
Diagnoses linked with this treatment include:
- Contracture of the masticatory muscles
- Post-surgical adhesions of the fascial or cutaneous tissues
Related Reading: How to Diagnose Masticatory Muscle Disorders
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