Temporomandibular Joint Dysfunction

Abstract

Temporomandibular joint (TMJ) dysfunction (also known as myofascial pain dysfunction of the muscles of mastication) is characterized by pain in the joint itself that radiates into the mandible, ear, neck, and tonsillar pillars. The TMJ is a true joint that is divided into upper and lower synovial cavities by a fibrous articular disk. Internal derangement of this disk may result in pain and TMJ dysfunction, but extracapsular causes of TMJ pain are much more common. The TMJ is innervated by branches of the mandibular nerve. The muscles involved in TMJ dysfunction often include the temporalis, masseter, and external and internal pterygoids; the trapezius and sternocleidomastoid may be involved as well. Headache often accompanies the pain of TMJ dysfunction and is clinically indistinguishable from tension-type headache. Stress is often the precipitating factor or an exacerbating factor in the development of TMJ dysfunction. A history of bruxism or jaw clenching is often present. Dental malocclusion may also play a role in its evolution.

Keywords

temporomandibular joint dysfunction, dental malocclusion, atypical facial pain, trigeminal neuralgia, bruxism, inflammatory arthritis

ICD-10 CODE M26.60

The Clinical Syndrome

Temporomandibular joint (TMJ) dysfunction (also known as myofascial pain dysfunction of the muscles of mastication) is characterized by pain in the joint itself that radiates into the mandible, ear, neck, and tonsillar pillars. The TMJ is a true joint that is divided into upper and lower synovial cavities by a fibrous articular disk. Internal derangement of this disk may result in pain and TMJ dysfunction, but extracapsular causes of TMJ pain are much more common. The TMJ is innervated by branches of the mandibular nerve. The muscles involved in TMJ dysfunction often include the temporalis, masseter, and external and internal pterygoids; the trapezius and sternocleidomastoid may be involved as well.

Signs and Symptoms

Headache often accompanies the pain of TMJ dysfunction and is clinically indistinguishable from tension-type headache. Stress is often the precipitating factor or an exacerbating factor in the development of TMJ dysfunction ( Fig. 11.1 ). A history of bruxism or jaw clenching is often present.

Dental malocclusion may also play a role in its evolution. Internal derangement and arthritis of the TMJ may manifest as clicking or grating when the mouth is opened and closed. If the condition is untreated, the patient may experience increasing pain in the aforementioned areas, as well as limitation of jaw movement and mouth opening.

Trigger points may be identified when palpating the muscles involved in TMJ dysfunction. Crepitus on range of motion of the joint suggests arthritis rather than dysfunction of myofascial origin. In severe cases, deviation of the mandible may occur ( Fig. 11.2 ).

Testing

Radiographs of the TMJ are usually within normal limits in patients suffering from TMJ dysfunction, but they may be useful to help identify inflammatory or degenerative arthritis of the joint as well as crystal deposition diseases ( Figs. 11.3 and 11.4 ). Arthroscopy and imaging of the joint can help the clinician identify derangement of the disk, as well as other abnormalities of the joint itself ( Figs. 11.5 and 11.6 ). Magnetic resonance imaging may provide more detailed information regarding the condition of the disk and articular surface and should be considered in complicated cases. A complete blood count, erythrocyte sedimentation rate, and antinuclear antibody testing are indicated if inflammatory arthritis or temporal arteritis is suspected. Injection of the joint with small amounts of local anesthetic can serve as a diagnostic maneuver to determine whether the TMJ is in fact the source of the patient’s pain ( Fig. 11.7 ).