Temporomandibular Joint Dysfunction and Pain Syndromes (MFPDS)

Synonym:

TMJ pain dysfunction syndrome, myofascial pain disorder, myofascial pain-dysfunction syndrome, facial arthromyalgia, craniomandibular dysfunction, Costen's syndrome

Definition:

Temporomandibular disorders (TMDs) refers to a group of disorders affecting the temporomandibular joint (TMJ), masticatory muscles and the associated structures.These disorders share the symptoms of pain, limited mouth opening and joint noises.

Epidemiology

Temporomandibular joint symptoms are relatively common, occurring in 10-25% of the population; only about 5% of people with symptoms will seek treatment. Temporomandibular disorders may occur at any age, but are more common in women and in early adulthood.

Aetiology

TMJ disorders are thought to have a multifactorial aetiology, but the pathophysiology is not well understood. Causes can be classified into factors affecting the joint itself, and factors affecting the muscles and joint function. The American Academy of Orofacial Pain has also produced a diagnostic classification.

Factors affecting muscles and joint function - myofascial pain and dysfunction

This type of TMJ problem is most common. Often it is difficult to determine a single cause, but contributing factors may be:

• Chronic pain syndromes or increased pain sensitivity.
• Psychological factors may contribute (as with other chronic pain syndromes).
• Muscle overactivity: bruxism1 (jaw clenching at night); orofacial dystonias.4
• Dental malocclusion was formerly considered to be an important factor; indeed TMJ dysfunction was often considered as a dental problem. However, the evidence does not support this, and TMJ dysfunction is now seen as a multifactorial problem rather than a dental condition.1,5

Factors affecting the joint

The most common problems are:

• Intra-articular disc derangement (various types)
• Osteoarthritis
• Rheumatoid arthritis

Other problems affecting the joint are:

• Other types of arthropathy, e.g. gout, pseudogout or spondyloarthropathy
• Trauma
• TMJ hypermobility or hypomobility
• Infection
• Congenital disorders, e.g. branchial arch disorder
• Tumours (rare)

Symptoms

The three cardinal symptoms of TMJ disorders are: facial pain, restricted jaw function and joint noise.

• Pain:
  • Located around the TMJ, but may be referred to the head, neck and ear.
  • Pain, located immediately in front of the tragus of the ear, projecting to the ear, temple, cheek and along the mandible, is highly diagnostic for temporomandibular disorder.
• Restricted jaw motion:
  • May affect mandibular movement in any direction.
  • Jaw movements increase the pain.
  • Patients may describe a generally tight feeling, which is probably a muscular disorder, or a sensation of the jaw "catching" or "getting stuck", which usually relates to internal derangement of the joint.1
• Joint noise:
  • Clicks and other joint sounds are common; they are not significant unless there are other symptoms.

Other symptoms:

• Ear symptoms - otalgia, tinnitus, dizziness.
• Headache.
• Neck pain.
• "Locking" episodes - inability to open or close the mouth. Inability to open the mouth is more common.

Examination

• Palpate the joint by placing the fingertips in the preauricular region just in front of the tragus of the ear. The patient is then asked to open their mouth and the fingertip will fall into the depression left by the translating condyle.
• Palpate head, neck and masticatory muscles for areas of tenderness
• Joint clicks or grating sounds on jaw movement may be palpable, or may be heard with a stethoscope over the preauricular area.
• Assess mandibular movement:
  • Measure the distance of painless vertical mouth opening, using inter-incisal distance (normal range 42-55 mm)
  • Observe the line of vertical jaw opening: straight or deviating, smooth or jerky
  • Examine lateral movements and jaw protrusion
• Assess other orofacial structures - salivary glands, oral cavity, dentition, ears and cranial nerves.

Differential diagnosis

• Giant cell arteritis (temporal arteritis).
• Cardiac pain (angina and acute coronary syndromes) can radiate to the neck and jaw, but is usually more acute.
• Dental problems.
• Trigeminal neuralgia.
• Migraine and other causes of headache.
• Herpes zoster.
• Other ENT disorders, e.g. salivary gland disorders and ENT neoplasms.

The location of the pain helps in diagnosis. The pain in TMDs is centred immediately in front of the tragus of the ear and projects to the ear, temple, cheek and along the mandible.1

Investigations

No tests may be needed in straightforward cases. Possible investigations are:

• Blood tests: ESR, CRP for inflammation.
• Plain radiographs - show gross bony pathology such as degeneration or trauma.
• CT or MRI scan of the joint. MRI scan shows the soft tissues and intra-articular disc well.
• Diagnostic nerve block.6
• Arthroscopy.

Management

• Initial care is usually with conservative treatment, which is effective in most cases.
• Psychological aspects of pain management are important7 - as with other chronic pain andsomatisation disorders.
• Surgical intervention may be used in selected cases, where there is structural pathology not responding to conservative treatment.
• With symptoms of locking: intermittent locking often responds to conservative treatment. A 'closed lock' (difficulty opening the mouth) which is longstanding, is more likely to need intra-articular steroid injection or arthroscopy.

Non-invasive (conservative) treatment

Non-drug treatment

• Explanation and reassurance:
  • Most TMJ disorders are benign and will improve with non-invasive treatment.
• Rest, patient education and self-care:
  • Limit excessive jaw movement by eating soft foods. Avoid wide yawning, singing, and chewing gum.
  • Massage affected muscles and apply heat.
  • Use relaxation techniques; identify and reduce life stresses.
• Occlusal splints:
  • These are also known as "bite guards", and are removable devices made by dentists, to be worn over the teeth, on the principle that they may help with malocclusion or bruxism. Some studies have shown benefit from these, although systematic reviews did not find evidence of benefit.8,9
• Other treatments:7,10,11
• Acupuncture may be helpful, but the evidence is not conclusive.12

• Physiotherapy
• Behavioural techniques, e.g. postural training, biofeedback and proprioceptive retraining.

Drug treatment

• Analgesics, non-steroidal anti-inflammatory drugs and/or muscle relaxants.
• Antidepressants:
  • Tricyclic antidepressants, e.g. starting with a low or moderate bedtime dose for 2-4 weeks; if helpful, continue for 2-4 months and then taper down to a low maintenance dose.
  • An alternative is a newer antidepressant such as a selective norepinephrine reuptake inhibitor, e.g. duloxetine.
  • Selective serotonin reuptake inhibitor (SSRI) antidepressants have been used, but some (fluoxetine and paroxetine) may increase bruxism and are not recommended.
• Benzodiazepines have been used, but there is a risk of dependence.
• One small case study suggested that tiagabine may be helpful for bruxism.13

Invasive treatments

• Intra-articular injection, using steroid or hyaluronic acid.14,15 The effectiveness of hyaluronic acid is uncertain.16
• Surgery may be indicated for some patients, mainly when conservative treatments are not successful. It is usually supported by non-invasive treatment before and afterwards.17 Surgical options include:
  • Therapeutic arthroscopy.
  • Arthrocentesis.
  • Removal of loose bone fragments.
  • Reshaping the condyle.
  • More complex procedures, including joint replacement,6 depending on the pathology involved.
• Botulinum toxin A (BtA) injections:
  • These may help when excessive muscle activity or dystonia is a major factor. This method has been used successfully to treat both excessive clenching and recurrent TMJ dislocation.4However, a literature review of BtA use in chronic facial pain suggested that it was no better than other treatments.
  
  
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