Temporomandibular Joint Dysfunction and Pain Syndromes

Synonym: Costen's syndrome, Myofascial pain-dysfunction syndrome, Facial arthromyalgia

Temporomandibular disorders refers to a group of disorders affecting the temporomandibular joint (TMJ), masticatory muscles, and associated structures.These disorders share symptoms such as pain, limited mouth opening and joint noises.¹

Although James Costen was not the first to describe the syndrome, he developed an integrated and systematic approach, predominantly ascribing the symptoms to dental malocclusion. Recently, the use of the eponym has decreased, as dental malocclusion has assumed a lesser role in explaining many of the symptoms formerly ascribed to it.

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.

The aetiology of the most common types of temporomandibular disorders is complex and is still largely unresolved.¹ Causes can be classified into factors affecting the joint itself, and factors affecting the muscles and TMJ function. The American Academy of Orofacial Pain has also produced a diagnostic classification.³

Factors affecting the joint

• Arthritis: degenerative, rheumatoid, or metabolic (gout and pseudogout)³
• Spondyloarthropathies³
• Trauma³
• Osteoarthrosis of the TMJ: a localised degenerative disorder affecting mainly the articular cartilage, often in older people^1,4,5
• Factors involving the articular disc: the most common is disc displacement (also known as internal derangement), which interferes mechanically with the normal range of mandibular activity.¹ Disc disorders can be classified in more detail.^5,6

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:

• Muscle overactivity: bruxism¹ (jaw clenching at night); orofacial dystonias⁷
• Chronic pain syndromes or increased pain sensitivity⁸
• Psychological factors may contribute^1,9
• 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.^1,10

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

• Pain is the most common symptom. It is usually 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.
• Joint noise is common in asymptomatic people and is not significant in the absence of pain.
• Restricted jaw function can affect mandibular movement in any direction. Patients may describe a general tight feeling, which is probably a muscular disorder;or a sensation of the jaw "catching" or "getting stuck", which usually relates to internal derangement.¹
• Ear symptoms may also occur, due to the close anatomical relationship between the TMJ joint, muscles and ear structures. Symptoms include otalgia, tinnitus, vertigo, ear fullness and hyper/hyperacusis.¹¹
• Locking episodes of the jaw may occur: "Open lock" is the inability to close the mouth, with the mandibular condyle dislocated anteriorly; it is painful if not reduced quickly. "Closed lock" is the inability to close the mouth due to pain or disc displacement.¹²

• Palpate the joint by placing the finger tips in the preauricular region just in front of the tragus of the ear. The patient is then asked to open their mouth and the finger tip 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.
• Mandibular movement is assessed by:
  • Measuring the distance of painless vertical mouth opening, using inter-incisal distance (normal range 42-55 mm)
  • Observing the line of vertical jaw opening: straight or deviating, smooth or jerky

• Giant cell (temporal) arteritis may cause "jaw claudication" symptoms. It should be considered in patients over 50 years old, and is important to diagnose, as it requires urgent treatment.
• Trigeminal neuralgia
• Migraine and other causes of headache
• Other ENT disorders, such as salivary gland disorders and rarely, neoplasms, can mimic TMJ symptoms

What distinguishes temporomandibular disorders from other possible diseases is the pain, which is specifically centred in and around the preauricular region and may be accompanied by clicking or grating sounds with mandibular function and restricted mouth opening.

Investigations are mainly required to look for other causes, or to evaluate joint pathology.

• ESR and CRP may be used to look for temporal arteritis and systemic joint disease (but note that a normal ESR does not exclude temporal arteritis).
• Plain radiographs will show any gross bony pathology such as degeneration or trauma.¹
• MRI is increasingly used, as it can show more subtle changes and can visualise the intra-articular disc.^1,13

Noninvasive treatments are recommended for the initial care of nearly all TMD patients, because they achieve good relief for the majority of patients. Surgical intervention may be used in selected cases, in addition to noninvasive treatments.³

Noninvasive treatments

Drug treatments

• Analgesics, NSAIDS, muscle relaxants and antidepressants are options.¹
• One small case study suggested that tiagabine may be helpful for bruxism.¹⁴

Non-drug treatments

Options, which may be used in combination, are:

• Explanation and reassurance: most TMJ disorders are benign and will improve with noninvasive treatment.¹
• Patient education and self-care: this includes: limiting excessive mandibular function by eating soft foods; avoiding wide yawning, singing and chewing gum; massaging affected muscles and applying heat; relaxation techniques; identifying and reducing life stresses.^1,15 Jaw exercises can also be used.¹⁶
• Physiotherapy and postural training^1,15,17
• Behavioural therapy: biofeedback and proprioceptive retraining programmes.^17,18
• 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,¹ but systematic reviews show no evidence of benefit from occlusal therapy.^19,20
• Acupuncture has been reviewed but the evidence is not conclusive.²¹

Invasive treatments

• Botulinum toxin A (BtA) injections 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.⁷ However, a literature review of BtA use in chronic facial pain suggested that it was no better than other treatments.²²
• Intra-articular steroid injection has been used to treat TMJ inflammation in adults,²³ and also for children with juvenile idiopathic arthritis affecting this joint.²⁴
• Surgery is indicated for a small minority of patients only.¹There is a spectrum of surgical procedures for the treatment of TMD, ranging from simple arthrocentesis and lavage to more complex open joint surgical procedures. Surgery is usually supported by noninvasive treatment before and afterwards.²⁵ Randomised trials of surgical intervention are lacking.²⁶