21.2 Temporomandibular Disorders and Neuromuscular Conditions
Key Takeaways
Most temporomandibular disorders are managed conservatively with education, self-care, short-term NSAIDs, physiotherapy and a stabilization splint, and irreversible occlusal adjustment is not a first-line treatment.
A disc displacement without reduction with limited opening (closed lock) follows a history of clicking that stopped, and the jaw deviates toward the affected side on opening.
An acute anterior TMJ dislocation is reduced by pressing down on the posterior mandible with the thumbs and then guiding the jaw backwards, followed by limiting wide opening.
Bell palsy is a lower motor neurone facial palsy that involves the forehead; oral corticosteroids within 72 hours and eye protection are the key management, whereas forehead sparing suggests an upper motor neurone lesion such as a stroke.
New temporal headache with jaw claudication in a patient over 50 suggests giant cell arteritis, which needs same-day medical referral and corticosteroids to prevent blindness.
Temporomandibular disorders (TMD) are the most common non-dental cause of orofacial pain. The differential diagnosis of other orofacial pains, including trigeminal neuralgia and referred cardiac pain, is covered in the previous section; this section focuses on the joint, the masticatory muscles and the neuromuscular conditions.
Diagnostic Categories (DC/TMD)
| Category | Key findings |
|---|---|
| Myalgia / myofascial pain | Pain in masticatory muscles, worse with function; familiar pain on palpation; myofascial pain with referral spreads beyond the palpated site |
| Arthralgia | Pain in the joint on palpation or movement |
| Disc displacement with reduction | Reciprocal click on opening and closing; normal range of movement |
| Disc displacement with reduction with intermittent locking | Click plus brief episodes of limited opening |
| Disc displacement without reduction with limited opening (closed lock) | History of clicking that stopped with sudden limitation; maximum assisted opening below about 40 mm; deviation toward the affected side |
| Degenerative joint disease | Crepitus; flattening, erosion or osteophytes on CBCT |
| Subluxation | Jaw locks open in a wide position and the patient needs a maneuver to close |
| Headache attributed to TMD | Temporal headache modified by jaw movement |
Normal maximum opening is roughly 40-55 mm.
Examination: palpation of muscles and joints, range of motion and deviation, joint sounds, occlusion, parafunction (bruxism, clenching), and psychosocial factors (stress, sleep, depression). Imaging: panoramic radiograph for screening; CBCT for bony changes; MRI for disc position and joint effusion.
Management
- Education and self-care: soft diet, avoid wide opening and gum chewing, warm or cold packs, jaw rest, habit awareness.
- Medication: short-term NSAIDs; muscle relaxants at night; low-dose tricyclic antidepressants for chronic myalgia.
- Physiotherapy and jaw exercises.
- Stabilization (Michigan-type) splint covering all teeth in one arch; a reversible therapy.
- Psychological support (cognitive behavioral therapy) for chronic pain.
- Arthrocentesis for closed lock not responding to conservative care; arthroscopy and open joint surgery for selected cases.
Irreversible occlusal adjustment is not a first-line TMD treatment. Most patients improve with conservative care, and symptoms often fluctuate over time.
When to Refer
Refer for specialist assessment when there is progressive limitation of opening, a changing occlusion (for example a developing open bite or midline shift), swelling over the joint, sensory loss, persistent pain despite several months of conservative care, or features that suggest a tumor or systemic arthritis. These "red flags" are uncommon but should not be dismissed as simple TMD.
Acute TMJ Dislocation
The condyle moves anterior to the articular eminence and the patient cannot close; there is a depression in front of the tragus and the mouth is held open.
Reduction: stand in front of the seated patient, place gauze-wrapped thumbs on the mandibular molars or external oblique ridges, press down to free the condyle below the eminence, then push backwards and allow the jaw to close. Muscle spasm may need local anesthetic or sedation. Afterwards: limit opening (support the chin when yawning) and soft diet for a while. Recurrent dislocation may need sclerosant injection, botulinum toxin to the lateral pterygoid or surgery (eminectomy).
Ankylosis and Growth Disorders
- TMJ ankylosis (fibrous or bony) follows trauma (often a childhood condylar fracture), infection or juvenile arthritis; causes severe limitation and mandibular growth disturbance with facial asymmetry; treated surgically with early physiotherapy.
- Condylar hyperplasia: progressive asymmetry with chin deviation away from the affected side.
- Juvenile idiopathic arthritis: condylar resorption and retrognathia with anterior open bite.
Neuromuscular and Neuropathic Conditions
| Condition | Features | Management |
|---|---|---|
| Bell palsy | Sudden unilateral lower motor neurone facial palsy including the forehead; idiopathic (linked to HSV) | Oral corticosteroids within 72 hours; eye care (lubricant, taping at night); most recover |
| Stroke (upper motor neurone) | Facial weakness sparing the forehead with limb signs | Emergency referral |
| Facial nerve paralysis after an IANB | Needle passed too far posteriorly into the parotid gland; immediate palsy lasting a few hours | Reassure; protect the eye (close it, patch); resolves when anesthesia wears off |
| Burning mouth syndrome | Burning tongue or mouth daily for months with normal mucosa, mostly in post-menopausal women | Exclude candidiasis, xerostomia, iron, B12 and folate deficiency, diabetes, denture allergy and drugs; topical clonazepam, CBT |
| Glossopharyngeal neuralgia | Electric pain in the throat, tonsil and ear triggered by swallowing or talking | Carbamazepine; refer |
| Post-herpetic neuralgia | Pain persisting after zoster in a trigeminal division | Topical and systemic neuropathic agents |
| Giant cell arteritis | Over 50; temporal headache, scalp tenderness, jaw claudication, visual symptoms; raised ESR and CRP | Same-day medical referral; corticosteroids to prevent blindness |
| Oromandibular dystonia, tardive dyskinesia | Involuntary jaw and tongue movements; antipsychotic drugs | Medical management; botulinum toxin |
| Bruxism | Sleep or awake clenching and grinding; tooth wear, fractures, muscle hypertrophy | Splint protection, habit management, review of contributing drugs |
Exam Traps
- Clicking that stops suddenly with limited opening is a closed lock, not an improvement.
- Bell palsy involves the forehead; forehead sparing suggests a central cause.
- A facial palsy appearing during an IANB injection is temporary; protect the eye.
A 26-year-old had a click in the right TMJ for two years. Three days ago the clicking stopped, and now she can open only 25 mm with the mandible deviating to the right. What is the most likely diagnosis?
Disc displacement with reduction of the left joint, which has a reciprocal click
Acute anterior dislocation of both condyles with the mouth locked open
Myalgia of the left masseter muscle with normal joint function
Disc displacement without reduction with limited opening of the right joint
A patient yawns widely during treatment and cannot close the mouth. The jaw is fixed open with depressions in front of both ears. How is the dislocation reduced?
Ask the patient to bite hard on a cotton roll until the condyles slip back
Pull the mandible forward and upward so the condyles move over the eminence
Press downward on the posterior mandible with the thumbs, then push it backward
Push the chin firmly upward to force the teeth together and close the mouth
A 55-year-old has had a constant burning sensation of the tongue for eight months. The mucosa looks normal. Which step should come first?
Extract the teeth adjacent to the tongue, because sharp cusps always cause burning pain
Exclude secondary causes such as candidiasis, xerostomia, deficiencies and drugs
Start long-term systemic corticosteroids, because burning mouth is an autoimmune disease
Perform an incisional biopsy of the normal-looking tongue to look for carcinoma
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