Myofascial Pain Dysfunction Syndrome

Myofascial pain dysfunction syndrome is a regional pain disorder of the masticatory muscles, with tender trigger points, taut bands, pain on chewing and movement, and limited jaw function. It is the commonest temporomandibular disorder, accounting for about half of those seen in clinics.

It affects mainly women aged 20 to 50 years. Contributing factors are bruxism and clenching, psychological stress, anxiety and depression, poor sleep, trauma, and increased pain sensitivity.

Pathophysiology. Sustained muscle contraction and overload lead to local ischaemia, release of inflammatory and algogenic substances, and the formation of trigger points. Central sensitisation maintains the pain and spreads it.

Pain is not usually explained by joint disease. Co-existing conditions are tension type headache, migraine, fibromyalgia, irritable bowel syndrome and insomnia.

Dull, aching, regional pain in the cheek, temple, jaw and ear that gets worse with chewing and jaw use, stress and at the end of the day, with stiffness, limited opening, and tenderness of the masseter and temporalis. Referred pain to the teeth, ear and head is common. Clicking may coexist.

Palpation shows taut bands with focal tender points that reproduce the pain. The opening range is mildly reduced with a soft end feel. Ask about parafunction, sleep, stress, headache and other pains.

Jaw pain on chewing (jaw claudication) in a person over 50, with headache, scalp tenderness, visual symptoms or polymyalgia, needs same day assessment for giant cell arteritis. Fever and swelling suggest infection, and neurological signs need further assessment.

• Clinical diagnosis from history and examination: pain in the masticatory muscles that is reproduced by palpation of the masseter and temporalis (with 1 kg of pressure for 5 seconds), and by jaw movement, with a pattern of local or spreading pain.
• Mouth opening in millimetres, joint examination, occlusion and dental examination for tooth wear.
• Screening questionnaires for depression, anxiety, sleep and pain sensitivity.
• Imaging is not needed in typical cases. Panoramic radiograph, CT or MRI if joint disease, tumour or other pathology is suspected.
• ESR and C-reactive protein in anyone over 50 years of age with new jaw pain, with temporal artery biopsy or ultrasound if giant cell arteritis is suspected.

Differential diagnosis.

• Temporomandibular joint disorders (internal derangement, osteoarthritis)
• Giant cell arteritis
• Tension type headache and migraine
• Trigeminal neuralgia and other neuropathic pain
• Dental pain, pulpitis and sinusitis
• Parotid disease and salivary stones
• Cardiac pain with jaw radiation
• Eagle syndrome and tumour

• Education and reassurance, with explanation of the benign course. Self-care: heat, gentle massage, stretching, a soft diet for a short period, avoiding gum chewing and nail biting, and stress reduction. Most patients improve within weeks to months.
• Physiotherapy and jaw exercises, relaxation training, cognitive behavioural therapy and sleep hygiene.
• Stabilisation splint worn at night for 3 to 6 months for bruxism, with review of occlusal contacts. Do not advise irreversible occlusal adjustment.
• Drugs for a short time:
  • Ibuprofen 400 mg three times daily with food, or naproxen 250 to 500 mg twice daily with food, for 2 weeks, with a proton pump inhibitor in people at risk of ulcer. Avoid in renal impairment, peptic ulcer and anticoagulation. Paracetamol 1 g every 6 hours (maximum 4 g daily).
  • Cyclobenzaprine 5 to 10 mg orally at night for up to 2 to 3 weeks, avoided with arrhythmia, heart block, recent myocardial infarction, hyperthyroidism and monoamine oxidase inhibitors, with warning of drowsiness.
  • Amitriptyline 10 mg orally at night, increased by 10 mg each week to 25 to 50 mg (maximum 75 mg) for persistent pain, with caution in cardiac conduction disease, glaucoma, urinary retention, epilepsy and in older adults, with lower doses.
• Trigger point injection with lidocaine 1% 0.5 to 1 mL into each point, or dry needling, for focal tender points not responding. Botulinum toxin has mixed evidence and is not routine.
• Treat anxiety, depression and other pain conditions with a multidisciplinary team.
• Giant cell arteritis: prednisolone 40 to 60 mg orally each morning immediately, without waiting for biopsy, with urgent specialist assessment and bone, gastric and glucose protection.

Special groups. Pregnancy: use paracetamol and non-drug measures, and avoid NSAIDs from 28 weeks. Older adults need low doses of amitriptyline and attention to falls.

Monitoring. Review at 4 to 6 weeks for pain, opening and function, and at 3 months. Persistent pain beyond 3 months needs a multidisciplinary pain clinic assessment.

Referral and escalation. Refer to an orofacial pain clinic or oral and maxillofacial surgery for chronic or refractory pain. Refer to a psychologist or pain clinic as indicated. Same day referral for suspected giant cell arteritis.