Trismus is commonly referred to as lockjaw and is usually due to sustained tetanic spasms of the muscles of mastication. Although it was initially described in the setting of tetanus, it is now used to refer to a bilateral restriction in mouth opening from any cause.
The causes of limited mouth opening include trauma, infection, temporomandibular joint disorders (TMDs), neurological disorders, rheumatoid arthritis, drugs, tumors, hyperplasia of the coronoid process, etc. This condition can interfere with various medical treatments that require access to the oral cavity.
Having difficulty opening your mouth fully is called trismus. Trismus is a common side-effect of head and neck cancer treatment (surgery or radiation).
Although trismus much more commonly presents as a temporary complication, it can become a permanent condition if a patient does not undergo rehabilitative treatment in a timely manner.
When someone can't open his or her mouth wider than 1.3 inches, they are considered to have trismus. It can be caused by damage or injury to the jaw, and it can also arise as a result of TMD.
The 3 Finger Test
A quick and easy way to identify a possible case of Trismus is to place three of your fingers, stacked, between your upper and lower teeth, or dentures. If the mouth can open wide enough to accommodate them comfortably, then Trismus is unlikely to be a problem.
Suggest taking analgesics: ASA or acetamiophen 325 mg, 1-2 tablets every 4-6 hrs; or ibuprofen 200 mg, 1-2 tablets every 4 hrs. Muscle relaxants may be used in combination with analgesics or alone. Benzodiazepines may also be used, such as diazepam (2-5 mg, 3 times/day).
Symptoms of trismus include: Increased jaw pain. Inability to open the jaw (you cannot fit 3 fingers [lined up vertically] between the top and bottom teeth in the front of the mouth). A "spasm" or “tight” sensation when attempting to open the mouth.
But left untreated, trismus can affect people's ability to eat and regain strength after treatment. It can affect their ability to communicate, making them feel frustrated or isolated. If cancer treatment makes it hard for you to open your mouth, let your healthcare provider know.
Trismus caused by inflammation resolves by itself in due course, without need of any intervention. Whereas, when there is infection, trismus persists for a prolonged duration and it may even aggravate. This can be controlled by prescribing antibiotics.
Restricted mouth opening (RMO) and trismus are terms commonly used in oral oncology in instances where there is difficulty in mouth opening. The term trismus in oral oncology is mainly used to indicate the radiation-induced fibrosis of the muscles of mastication.
Remember that for most people, discomfort from TMJ disorders will eventually go away on its own. Simple self-care practices are often effective in easing symptoms. If treatment is needed, it should be based on a reasonable diagnosis, be conservative and reversible, and be customized to your special needs.
Generally, trismus is gradually alleviated or disappears within approximately 1 to 2 weeks post-operatively; however, in very rare cases, trismus persists for >1 month.
If you feel like you might have Trismus or lockjaw, it is important that you visit an ENT hospital. They might refer you to a dental surgeon and an orthopedician, based on the severity of the condition.
Several techniques are useful, including the use of tongue depressors of serially increasing size inserted between the incisors or the molars. Patients need to know that trismus that occurs 1 year after treatment will be permanent and that there is no good surgical or medical therapy.
Patients who have developed trismus are at risk for joint degeneration, as well as tightening of connective tissue. Studies have shown that passive motion can reverse the effects of immobility on the joint, while stretching can make connective tissue more flexible.
Trismus or lock jaw due to masseter muscle spasm, can be a primary presenting symptom in tetanus, Caused by Clostridium tetani, where tetanospasmin (toxin) is responsible for muscle spasms.
If you are experiencing issues such as jaw clicking and locking, you may have temporomandibular joint dysfunction (usually referred to as TMJ/TMD). TMJ/TMD occurs when the temporomandibular joint becomes damaged or inflamed due to an injury, inflammatory disorders, and other such issues.
These side effects may include xerostomia (dry mouth), mucositis, and pain. Other side effects associated with trismus include pain in the ear and jaw, headaches, and trouble hearing. Your chance of having trismus is related to the amount of radiation your jaw got during treatment.
Sugar free chewing gum may be helpful to keep your jaw moving. Chewing gum that contains xylitol will help to protect your teeth from dental decay. Check with your Speech and Language Therapist that it is safe for you to chew gum. Keep help prevent your jaw from becoming stiff, exercise your jaw muscles as follows.
A medial pterygoid myospasm can occur secondary to an inferior alveolar nerve block. This disorder generally is treated by the application of heat, muscle stretches, analgesic and/or muscle relaxant ingestion, and a physical therapy referral.
For this reason, skeletal muscle relaxants are often prescribed in the treatment of acute temporomandibular disorders (jaw locking, trismus, masticatory, and cervical myofascial pain).