What is the treatment for trismus?

Treatment of Trismus

Patients with trismus should be immediately referred to rehabilitation specialists and dental professionals for early intervention with physical therapy and stretching exercises, as this represents the mainstay of treatment and should begin as soon as the condition is diagnosed. 1

Initial Assessment and Etiology Determination

• Evaluate for underlying malignancy first: When trismus presents after head and neck cancer treatment, determine whether it results from the treatment itself or represents the first sign of tumor recurrence 2
• Assess severity: Trismus is defined as mouth opening ≤35 mm (maximal interincisal distance) 2
• Identify the cause: Common etiologies include radiation therapy to masticatory muscles, tumor invasion (especially medial pterygoid muscle), post-surgical complications, temporomandibular joint disease, or iatrogenic injury from dental procedures 1, 2, 3

Primary Treatment Approach: Conservative Management

Physical Therapy (First-Line Treatment)

• Exercise therapy is the cornerstone and should start as soon as possible after diagnosis 2
• Specific modalities include:
  • Gentle stretching exercises with tongue blades 1
  • Custom mouth opening devices for rehabilitation 1
  • Dynamic splinting devices used three times daily 4
  • Massage, ultrasound, neuromuscular electrical stimulation (NMES), and moist heat application 4

Pharmacological Adjuncts

• Prescribe nerve-stabilizing agents such as pregabalin, gabapentin, or duloxetine to combat pain and muscle spasms, which facilitates compliance with physical therapy and stretching devices 1
• Consider analgesics (acetaminophen 500 mg TID) or NSAIDs (ibuprofen 600 mg TID) for pain control 1
• Muscle relaxants may be indicated for acute myospasm cases 3
• Corticosteroids in decreasing doses (e.g., dexamethasone 8 mg QD tapering over 4 days) can reduce inflammation and associated trismus 1

Specialist Interventions

• Botulinum toxin type A injections into affected muscles for refractory pain and spasm control when conservative measures fail 1

Surgical Management for Refractory Cases

Coronoidectomy should be considered for patients who fail at least 3 months of aggressive physical therapy and maintain interincisal distance ≤20 mm. 5

• Surgical outcomes: Mean improvement of 22.1 mm at 6 months and 21.8 mm at 12 months post-coronoidectomy, with all patients maintaining ≥35 mm opening 5
• Indications: Trismus refractory to conservative management in head and neck cancer patients who have completed radiation therapy 5

Prevention Strategies

Prevention is more important than treatment and should be prioritized in at-risk populations 2

For Radiation Therapy Patients

• Maintain range of motion exercises throughout and after radiation treatment 1
• Intensity-modulated radiation therapy (IMRT) appears to lower the percentage and severity of radiation-induced trismus compared to conventional techniques 2
• Monitor radiation doses to mastication structures, as trismus prevalence increases with higher doses 2

For Surgical Candidates

• Pre-operative assessment: In patients with suspected thymoma or conditions requiring surgery near masticatory structures, evaluate for trismus severity to determine if it will affect surgical exposure 1, 6
• Abort procedures if trismus prevents adequate surgical exposure or instrument positioning 1

Common Pitfalls to Avoid

• Delayed intervention: Waiting too long before starting physical therapy can lead to permanent functional impairment and fibrosis 2, 7
• Inadequate trial of conservative therapy: Proceeding to surgery without at least 3 months of aggressive physical therapy 5
• Missing tumor recurrence: Failing to rule out malignancy as the cause of new or worsening trismus in cancer patients 2
• Inadequate pain control: Uncontrolled pain prevents compliance with stretching exercises, which are essential for recovery 1