Trismus

Trismus is a reduced ability to open the jaws. There are a large number of potential causes, some of which are serious and warrant urgent treatment. Common causes of trismus are:

• acute and chronic temporomandibular disorders
• temporomandibular joint derangement
• oral infections, such as:
  • pericoronitis (associated with partially erupted wisdom teeth)
  • spreading odontogenic infection
  • peritonsillar abscess (a potential complication of tonsillitis)
• surgery (eg wisdom teeth removal)
• haematoma following dental injection
• tetanus
• acute dystonic reactions (eg drug-related)
• oral submucous fibrosis (common in parts of the world where areca nut [betel quid] chewing is frequent)
• head and neck radiotherapy.

Accurately determining the cause of trismus requires a thorough history, examination and, sometimes, imaging. Promptly initiating management can improve outcomes. Management is tailored to the cause, and may include dental treatment, physiotherapy or the use of passive range-of-motion devices.

Patients with ongoing trismus require prompt specialist referral to investigate less common causes (eg malignancies involving the temporomandibular joint or masticatory muscles, scleroderma).