(See also Overview of Temporomandibular Disorders Overview of Temporomandibular Disorders (TMD) The term temporomandibular disorders is an umbrella term for a group of musculoskeletal and neuromuscular conditions that involve the temporomandibular joint (TMJ), the masticatory muscles,... read more .)
This condition is the most common disorder affecting the temporomandibular region. It is more common among women and has a bimodal age distribution in the early 20s and around menopause Menopause Menopause is physiologic or iatrogenic cessation of menses (amenorrhea) due to decreased ovarian function. Manifestations may include hot flushes, night sweats, sleep disruption, and genitourinary... read more .
In the affected muscle, both pain and trigger points (which cause referred pain) may result from parafunctional behavior such as bruxism Bruxism Bruxism is clenching or grinding of teeth. Bruxism can abrade and eventually wear down enamel and dentin in the crowns of teeth, damage metal or ceramic dental crowns, and cause teeth to become... read more (clenching or grinding of the teeth), which is regarded as two distinct entities: sleep or awake bruxism, which have different etiologies.
Myofascial pain syndrome is not limited to the muscles of mastication. It can occur anywhere in the body, most commonly involving muscles in the neck, shoulders and back.
Symptoms and Signs of Myofascial Pain Syndrome
Symptoms include pain and tenderness of the masticatory muscles and often pain and limitation of jaw excursion. Both sleep bruxism Bruxism Bruxism is clenching or grinding of teeth. Bruxism can abrade and eventually wear down enamel and dentin in the crowns of teeth, damage metal or ceramic dental crowns, and cause teeth to become... read more and sleep-disordered breathing Obstructive Sleep Apnea Obstructive sleep apnea (OSA) consists of episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of apnea or... read more (such as obstructive sleep apnea and upper airway resistance syndrome) are associated with headache that is more severe on awakening and gradually subsides during the day. Such pain must be distinguished from giant cell arteritis Giant Cell Arteritis Giant cell arteritis involves predominantly the thoracic aorta, large arteries emerging from the aorta in the neck, and extracranial branches of the carotid arteries. Symptoms of polymyalgia... read more . Awake symptoms, including jaw muscle fatigue, jaw pain, and headaches, usually worsen if parafunctional behavior continues throughout the day.
The jaw deviates when the mouth opens but usually not as suddenly or always at the same point of opening as it does with internal temporomandibular joint derangement Internal Temporomandibular Joint (TMJ) Derangement The most common form of internal temporomandibular joint derangement is an anterior displacement of the articular disk in relation to the condyle. Often, joint pain and popping/clicking occur... read more . Exerting gentle pressure on the lower anterior teeth, the examiner can stretch the involved muscles and thereby assist the patient in opening the mouth another 1 to 3 mm beyond unaided maximum opening.
Diagnosis of Myofascial Pain Syndrome
A simple test may aid the diagnosis: 2 or 3 tongue blades are placed between the rearmost molars on each side, and the patient is asked to close the mouth gently (1, 2 Diagnosis references Myofascial pain syndrome (previously known as myofascial pain and dysfunction syndrome [MPDS or MFPDS]) can occur in patients with a normal temporomandibular joint. It is caused by muscle tension... read more ). The distraction produced in the joint space may ease the symptoms. X-rays usually do not help, except to rule out arthritis. If giant cell arteritis Giant Cell Arteritis Giant cell arteritis involves predominantly the thoracic aorta, large arteries emerging from the aorta in the neck, and extracranial branches of the carotid arteries. Symptoms of polymyalgia... read more is suspected, erythrocyte sedimentation rate (ESR) is measured.
Polysomnography should be done if sleep-disordered breathing is suspected.
1. Schiffman E, Ohrbach R, Truelove E, et al: 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. J Oral Facial Pain Headache 28(1):6-27, 2014. doi: 10.11607/jop.1151
2. Peck C, Goulet J-P, Lobbezoo F, et al: Expanding the taxonomy of the diagnostic criteria for temporomandibular disorders. J Oral Rehabil 41(1):2-23, 2014. doi: 10.1111/joor.12132
Treatment of Myofascial Pain Syndrome
Possibly temporary use of an anxiolytic or cyclobenzaprine at bedtime
Trigger point injections and other physical and behavioral therapy modalities
An oral appliance from a dentist can keep teeth from contacting each other and thereby reduce the damage caused by bruxism Bruxism Bruxism is clenching or grinding of teeth. Bruxism can abrade and eventually wear down enamel and dentin in the crowns of teeth, damage metal or ceramic dental crowns, and cause teeth to become... read more . Over-the-counter heat-moldable (boil and bite) mouth guards are available from many sporting goods stores or drugstores; however, these types of devices should be used briefly and only as short-term diagnostic tools. Because these mouth guards may cause unwanted tooth movement or create a paradoxical increase in muscle activity, oral appliances should ideally be fabricated, fitted, and adjusted by a dentist.
Low doses of a benzodiazepine at bedtime are often effective for acute exacerbations and temporary relief of symptoms. Cyclobenzaprine may facilitate muscle relaxation. However, in patients with associated sleep disorders Obstructive Sleep Apnea Obstructive sleep apnea (OSA) consists of episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of apnea or... read more , such as sleep apnea, anxiolytics and muscle relaxants should be used with caution because they can aggravate these conditions. Mild analgesics, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen, individually or in combination are indicated. Because the condition is chronic, opioids should not be used, except perhaps briefly for acute exacerbations. In some cases of chronic pain, antidepressant medication is useful under medical supervision.
The patient must learn to stop parafunctional behavior (eg, clenching the jaw, grinding the teeth) when awake. Hard-to-chew foods and chewing gum should be avoided. Physical therapy, biofeedback to encourage relaxation, and counseling help some patients.
Physical modalities include trigger point injections, transcutaneous electric nerve stimulation Electrical stimulation Treatment of pain and inflammation aims to facilitate movement and improve coordination of muscles and joints. Nondrug treatments include therapeutic exercise, heat, cold, electrical stimulation... read more (TENS), and “spray and stretch,” in which the jaw is stretched open after the skin over the painful area has been chilled with ice or sprayed with a skin refrigerant, such as ethyl chloride. Botulinum toxin may be used successfully to relieve muscle spasm.
Most patients, even if untreated, customarily have diminished or cessation of significant symptoms within 6 to 12 months.
Myofascial pain syndrome is a more common cause of temporomandibular pain than temporomandibular joint derangement.
Tension, fatigue, and (rarely) spasm of the masticatory muscles may result from parafunctional behavior (eg, bruxism).
Patients have pain and tenderness of the masticatory muscles, painful limitation of jaw excursion, and sometimes headache.
Use of oral appliances, benzodiazepines or muscle relaxant during sleep may help, along with nonopioid analgesics; behavioral modalities and physical therapy are sometimes appropriate.