TMJ Disorders

Temporomandibular disorder or TMD can cause any type of pain or irritation in the jaw joint and in the muscles that control jaw movement. However, it is usually hard to find out the exact cause of TMJ disorder since it could be a combination of different factors including but not limited to genetics, arthritis, or myofascial. I will talk more about the different causes of TMJ pain below:

Myalgia (muscle pain):

Patients usually present with pain in the jaw, temple, or in front of the ear. Pain is also modified by jaw movements. In terms of the physical examination, patients usually present with pain localized in the temporalis or masseter muscle. The practitioner will be usually able to reproduce the pain by palpation of the masseter and temporalis as well as active and passive jaw opening.

There are different types of myalgia such as local myalgia which is pain localized to the site of palpation, and myofascial pain which is when pain spreads beyond the site of palpation but is also localized to the muscle. Finally, myofascial pain with a referral which is when the pain will be traveling beyond the boundary of the muscle that is palpated.

Tendinopathy:

This can usually result from bruxism or habitual grinding of the teeth which can happen during sleep. Sleep bruxism is considered a sleep-related movement disorder. People who clench or grind their teeth during sleep are more likely to have other sleep disorders such as snoring and pauses in breathing. It can cause tenderness as well as swelling of the anterior portion of the temporalis tendon. Palpating just above the zygomatic arch when the jaw is slightly open as well as tenderness at the insertion to the coronoid process is indicative of tendinopathy.

TMJ due to Fibromyalgia (Central pain disorder):

Those who are suffering from fibromyalgia or have central sensitization are more prone to get widespread pain in their bodies. The pain is usually more debilitating. In a study that were 162 female subjects who had a history of FM, those with FM reported more symptoms of MFP myofascial face pain as well as major depression and somatization symptoms.   

Myositis:

Myositis means inflammation of the muscles that you use to move your body. An injury, infection, autoimmune disease, or drug side effects can cause it. Some of their symptoms is weakness, swelling, and acute, constant pain.

Tardive dyskinesia:

It is a type of disorder that results in involuntary, repetitive body movements which in this case would be face or mouth. It is usually more prone in older patients, who are psychotic using antipsychotic or dopamine antagonists for long periods or use neuroleptics, anticholinergics, toxins, and substances of abuse. A case of the irreversible syndrome of persistent tardive dyskinesia attributed to long-term intake of chlorpromazine.   This can cause a repetitive strain injury to the muscles of mastication.

Oromandibular dystonia:

This is a focal dystonia characterized by forceful contraction of the face, jaw, and tongue causing difficulty in opening and often affecting chewing and speech. It is often associated with dystonia of the neck muscles and symptoms usually begin later in life between the ages of 40 and 70 years and appear to be more common in women than men. The causes could be genetics, drug-induced, trauma, and injury to CNS.

References:

1. Schiff man E, Ohrbach R, Truelove E, Look J, Anderson G, Goulet JP, List T, Svensson P. Diagnostic criteria for temporomandibular disorders (DC/TMD) for clinical and research applications: recommendations of the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group. Journal of oral & facial pain and headache. 2014;28(1):6.

2. Kobayashi RM. Orofacial dyskinesia: Clinical features, mechanisms and drug therapy. Western Journal of Medicine. 1976 Oct;125(4):277.

3. Raphael KG, Marbach JJ, Klausner J. Myofascial face pain: clinical characteristics of those with regional vs. widespread pain. The Journal of the American Dental Association. 2000 Feb 29;131(2):161-71.