Temporomandibular Joint Syndrome

What is temporomandibular joint syndrome?

Temporomandibular joint

Temporomandibular joint (TMJ) is a joint that connects the jaw to the skull. TMJ is located on both sides of the skull just in front of the ear. This joint provides the necessary movements of jaw. The joint is covered with fibrous capsule that attaches to the skull and mandible.

Between both bone surfaces there is a fibrous articular disc. It divides the joint in two sections. The anterior part attaches to the joint capsule, but the posterior part to mandibular fossa. The posterior part is called retrodiscal tissue and it is highly innervated and vascular. The joint is stabilized by several ligaments and joint muscles provide all the movements ^[1].

Causes

TMJ syndrome is a condition that causes pain and functional impairment of temporomandibular joint. There are 3 distinctive causes for TMJ syndrome:

• Myofascial pain dysfunction syndrome refers to pain in the TMJ due to increased muscle tension and spasm. There is no disorder of anatomic structures of the joint. This syndrome is mostly caused by psychological disorders:
  • Stress
  • Teeth grinding
  • Clenching of jaw
• Internal derangement: disorder of the joint, most commonly caused by position of articulating disc. This can be caused due to arthritis, trauma or genetics.
• Degenerative joint disease- degeneration of the articular surfaces due to arthritis^[2]. For other musculo-skeletal diseases also see-piriformis syndrome, patello-femoral pain syndrome, rotator cuff syndrome.

Other causes of TMJ are:

• Injury to the joint
• Uneven bite
• Specific diseases:
  • Rheumatoid arthritis
  • Gout
  • Fibromyalgia
• Genetic disorders affecting the anatomy (see Apert syndrome)
• With no specific cause^[3]

Symptoms

• Pain- dull, usually on one side just in front of the ear, increases during the day
• Radiation of pain to ear and jaw; pain gets worse when chewing
• Locking of the jaw
• Popping or clicking sound in the joint
• Headaches, neck, shoulder, back pain
• Difficulties biting, discomfort
• Inability to open the jaw completely
• Emotional discomfort- patient can feel embarrassed because of clicking sound in the joint
• Feeling of tiredness in the face ^[3,4]

Diagnosis

Relevant patient history

Some patients might previously had trauma to face or jaw. Patients might also have systemic disorders like rheumatoid arthritis, fibromyalgia or other conditions that might cause TMJ syndrome.

On some occasions patients have had clicking sound in the jaw for many years. Some make the jaw click on purpose (also see hypermobility syndrome) ^[4].

Physical examination findings

When examining the patient, doctor might find the following characteristics:

• Incomplete opening of the jaw. Normally the jaw opening can be measured from upper anterior teeth to lover anterior teeth and the range is around 4 cm.
• Facial muscle spasms that can be palpated
• Facial swelling (usually on one side)
• Clicking sound in the TMJ
• When palpating, the joint is tender or painful
• In advanced disease crepitation sound is present in the joint
• Deviation of lover part of the jaw- mandible^[3,4]

Laboratory studies

There are no specific laboratory examinations that can diagnose TMJ syndrome. However blood analysis should be taken in order to exclude other conditions:

• Complete blood count –to rule out acute infection
• Calcium, phosphate and alkaline phosphatase- abnormal levels of these elements can suggest possible bone disease
• Uric acid- high levels of uric acid suggest gout (also see Juvenile gout syndrome)
• Serum creatine, creatine phospohokinase- markers of muscle disease
• Erythrocyte sedimentation rate
• Rheumatoid factor- marker for rheumatoid arthritis^[4]

Imaging studies

• X-ray imaging- X-Ray can be used to exclude possible dislocation or trauma to the jaw.
• CT imaging- CT can show a more detailed view of the bone structures

• Ultrasonography
• MRI is the method of choice for TMJ syndrome.
  • Disc displacement signs are abnormal orientation of the disc in both open and closed mouth positions
  • Stuck disk- the disc is fixed to the temporal bone, it is not moving out of this position when mouth is opened or closed
  • Joint derangement signs are joint effusion, osteoarthritic changes, thickening of surrounding muscles^[5]

Other diagnostic measures

In order to diagnose TMJ syndrome, a diagnostic nerve block can be performed. TMJ is innervated by a branch of trigeminal nerve. To perform the diagnostic block, an anesthetic is injected below the skin in the area of the joint. If patient doesn’t feel pain relief, it suggests there is a different cause for the pain.

In some occasions arthroscopy is performed to diagnose TMJ syndrome ^[6].

Treatment

Medications

• Pain relief- non-steroid anti inflammatories can be used to reduce pain and inflammation. If over the counter drugs don´t help, stronger pain medications can be prescribed
• Tricyclic antidepressants- in small doses these drugs can relieve pain
• Muscle relaxants- if the pain is caused by clutching of jaw, muscle relaxants might reduce it^[4]

Non-drug therapy

• Oral splints
• Physical therapy: ultrasound, moist heat and cold, exercises
• Counseling in case of teeth grinding, leaning on the chin, biting fingernails^[3]

Invasive treatments

• Arthrocentesis- irrigation with fluid through small needles, in order to remove debris and byproducts of inflammatory process
• Injections- previously mentioned diagnostic nerve block can also be a treatment option. On some occasions injection of botulinum toxin A is injected in the jaw muscles
• Arthroscopy- used to avoid open joint surgery on some occasions
• Modified condylotomy – surgery performed on the mandible (lower part of the jaw) to relieve pain caused by locking of the joint
• Open-joint surgery- used if all other treatments are not successful and the cause of the pain is structural. The joint can be repaired or replaced^[3,4].

Treatment at home

There are some home remedies to help TMJ pain:

• Non-steroidal anti inflammatory drugs like ibuprofen. These medications can relieve pain and swelling
• Cold or heat packs together with jaw stretches
• Diet changes- eating soft foots can reduce the stress on the joint
• Avoid wide opening of the jaw- take small bites, try not to yawn
• Do not put pressure on the joint, for example resting hand on the jaw
• Avoid grinding teeth and clutching jaw during the day
• Use therapies to reduce stress and help to relax jaw muscles^[7]

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References

1. Anatomy of TMJ http://www.physio-pedia.com/TMJ_Anatomy
2. Causes of TMJ syndrome: http://www.nhs.uk/conditions/temporomandibular-joint-disorder/Pages/Introduction.aspx
3. Causes, symptoms and treatment of TMJ syndrome: http://www.mayoclinic.org/diseases-conditions/tmj/home/ovc-20209398
4. Detailed information about TMJ syndrome for patients and health professionals: http://emedicine.medscape.com/article/809598-overview#a4
5. Imaging of TMJ syndrome: https://radiopaedia.org/articles/temporomandibular-joint-dysfunction
6. TMJ syndrome information for health professionals: http://www.msdmanuals.com/professional/dental-disorders/temporomandibular-disorders/internal-temporomandibular-joint-derangement
7. Patient information about TMJ syndrome: http://www.webmd.com/oral-health/guide/temporomandibular-disorders-tmd#3