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Trismus is an uncontrolled inability to open the mouth or jaw. Trismus interferes with many daily activities—chewing, swallowing, talking, brushing teeth, even breathing. The condition may be caused by dental problems, cancer and cancer treatment, surgery, trauma, or other factors. With correct intervention from a physical therapist, trismus can improve in time, and full jaw function may return.

Physical therapists are movement experts. They improve quality of life through hands-on care, patient education, and prescribed movement. You can contact a physical therapist directly for an evaluation. To find a physical therapist in your area, visit Find a PT.

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What Is Trismus?

"Trismus" is a term used to describe any number of conditions that cause an uncontrolled inability to open the mouth or jaw. The most common cause of trismus is inflammation of the soft tissue of the mouth due to:

  • An impacted molar.
  • Removal of wisdom teeth.
  • Removal of the tonsils.

Less common causes of trismus are:

  • Radiation therapy to the face and neck.
  • Tetanus ("lockjaw"), an acute infection from bacteria that usually enter the body through a wound.
  • Myositis (muscle inflammation).
  • Jaw nerve damage.
  • Adhesions, or scarring, of the tissues around the jaw or tongue, which can develop after a long period of not moving the jaw.
  • Muscle atrophy (wasting) that can occur after as little as 3 days of not opening the jaw.
  • Poor oral hygiene.
  • Tumors or cancer.
  • Trauma to the jaw area.
  • Diseases, such as lupus and scleroderma.

Trismus can occur rather suddenly in the first 9 months after radiation near the temporomandibular joint. After that time the risk still exists, but the tightness tends to develop more slowly. Risks are greater if radiation treatments were done in the area of the TMJ or muscles involved in chewing, and particularly increase with higher doses of radiation treatment.

Trismus tends to improve slowly. Studies suggest treatment may take from 3 to 12 weeks. Early treatment is the best way to prevent more severe problems. Your physical therapist will design an individualized treatment program based on your specific condition to speed up the healing process, reduce the feeling of tightness in the jaw area, and help restore your normal jaw joint movement and your ability to chew.

Signs and Symptoms

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.
  • Difficulty chewing.
  • Difficulty talking.
  • Difficulty breathing.
  • Difficulty brushing or flossing your teeth.

If you have trismus you may be at risk for choking. Because you can't chew food as well, you might also have to change your diet, which could mean you're not getting adequate nutrition. Even just moving food around in your mouth may be difficult because the tongue also may lose some mobility, if affected by trismus. Left unchecked, the disuse of the TMJ may lead to atrophy or wasting of the muscles that move the jaw, and possible deterioration of the TMJ surfaces.

Your medical team may suggest additional treatments to complement your physical therapist’s treatment. The use of mouth splints to help with stretching has been proven effective. Other possible options include Botox injections to relax tight muscles, and surgery to muscle, bone, or the TMJ.

How Is It Diagnosed?

During your first visit with your physical therapist, your physical therapist will:

  • Review your medical history, and discuss any previous surgery, fractures, or other injuries to your head, neck, or jaw.
  • Conduct a physical examination of your jaw and neck.
  • Evaluate your posture and how your neck moves.
  • Examine the TMJ to find out how well it can open, and whether there are any abnormalities in jaw motion since you developed trismus.
  • Consider whether you might be a candidate for an oral device to help regain motion, and refer you to a dentist.

How Can a Physical Therapist Help?

Your physical therapist can help restore the natural movement of your jaw and improve your daily function. Trismus tends to develop slowly. In some people, it progresses so slowly that they don't notice it until they can only open their mouths half-way. The sooner you see your physical therapist, the better, because treatment that begins before trismus progresses is likely to be more efficient and effective.

Once you have received the diagnosis of trismus, your physical therapist will select the appropriate treatments to improve your jaw movement and relieve pain.

Improve Your Jaw Movement. Your physical therapist may prescribe stretches and range-of-motion exercises for the jaw. The instruction will include individualized frequency and intensity of movements to ensure your safety. Your physical therapist will recommend specific techniques, such as stretching or self-mobilization to minimize your pain and restore function.

Physical therapists also use skilled hands-on techniques (manual therapy) to gently increase movement and relieve pain in tissues and joints.

Your physical therapist may teach you special "low-load" strengthening exercises, which do not exert a lot of pressure on your TMJ, but can strengthen the muscles of the jaw and restore a more natural, pain-free motion. Your physical therapist also will teach you gentle exercises that you can do at home to help you steadily increase the opening of your jaw and improve the way it works.

Relieve Your Pain. If your pain is severe, your physical therapist may apply physical modalities, such as electrical stimulation or deep heating, to reduce pain and improve motion.

Can This Injury or Condition Be Prevented?

Prevention and early treatment make management of trismus easier. Seek help if you develop any of the symptoms described in this guide, such as jaw stiffness or spasms, or chewing problems. Consultation with a physical therapist and treatment with a mouth splint are often recommended before trismus begins in high-risk cases, especially for persons who have received high amounts of radiation to the jaw area to treat an oral cancer.

What Kind of Physical Therapist Do I Need?

All physical therapists are prepared through education and experience to treat a variety of conditions or injuries. You may want to consider:

  • A physical therapist who is experienced in treating people with orthopedic or musculoskeletal problems. Some physical therapists have a practice with a craniofacial or TMJ focus, meaning that they focus on movement disorders related to the skull and facial structures.
  • A physical therapist who is a board-certified clinical specialist or who completed a residency or fellowship in orthopaedics physical therapy. This therapist has advanced knowledge, experience, and skills that may apply to your condition.

You can find physical therapists who have these and other credentials by using Find a PT, the online tool built by the American Physical Therapy Association to help you search for physical therapists with specific clinical expertise in your geographic area.

General tips when you're looking for a physical therapist (or any other health care provider):

  • Get recommendations from family and friends or from other health care providers.
  • When you contact a physical therapy clinic for an appointment, ask about the physical therapists' experience in helping people with trismus.
  • During your first visit with the physical therapist, be prepared to describe your symptoms in as much detail as possible, and say what makes your symptoms worse.

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The American Physical Therapy Association believes that consumers should have access to information to help them make informed decisions and prepare them for their visit with a health care provider.

The following resources offer some of the best scientific evidence related to physical therapy treatment for trismus. They report recent research and provide information on the standards of practice both in the United States and internationally. They link to a PubMed* abstract (which may also offer free access to the full text) or other resources. You can read them or print out a copy to bring with you to your health care provider.

Pauli N, Svensson U, Karlsson T, Finizia C. Exercise intervention for the treatment of trismus in head and neck cancer - a prospective two-year follow-up study. Acta Oncol. 2016;55(6):686-692. Article Summary in PubMed.

Dıraçoğlu D, Şen Eİ, Vatansever S, Çapan N, Karan A. Physical therapy in cancer related vs non-cancer trismus. Stomatologija. 2016;18(4):107-111. Article Summary in PubMed.

*PubMed is a free online resource developed by the National Center for Biotechnology Information. PubMed contains millions of citations to biomedical literature, including citations in the National Library of Medicine’s MEDLINE database.