Lockjaw, also called trismus, is when you have limited range of motion in your jaw that makes it difficult to open your mouth. For people undergoing treatment for head and neck cancer, lockjaw is a common complication.
Lockjaw can cause problems with eating, hygiene, dental work, examinations of the mouth, speaking, swallowing, and chewing, according to Memorial Sloan Kettering Cancer Center. It can also restrict your airways. If speaking becomes difficult, communication also may be limited. You may not be able to articulate words properly, making it hard for others to understand what you are saying.
Because lockjaw can cause these life-impacting issues, it’s important to identify and treat it early.
How common is lockjaw in people with head and neck cancer?
Lockjaw can occur in those with cancerous tumors that involve the bones, muscles, and nerves that open the mouth, according to Memorial Sloan Kettering Cancer Center. Six months after treatment for head and neck cancer, 38 percent of people have lockjaw, according to a 2013 study published in Acta Oncologia; at one year, this drops down to 28 percent.
Why does cancer treatment cause lockjaw?
There are several aspects of head and neck cancer treatment that can lead to the development of lockjaw, including radiation, maxillectomy, and muscle atrophy.
Between 10 and 40 percent of people who receive radiation therapy for head and neck cancer develop lockjaw, according to the Oral Cancer Foundation. People who have had previous radiation therapy are at greater risk than those receiving radiation for the first time.
During radiation, damage to the muscles, tendons, and connective tissue within the face and neck may cause lockjaw. When a muscle is damaged, your body guards against further pain by contracting the muscle. This is a reflex, not a choice, so you can’t control over whether it happens. The muscle contraction causes a loss of range of motion in the jaw, according to the Oral Cancer Foundation.
The symptoms of lockjaw may appear any time after the radiation, up to 12 months. Usually, the tightening slowly increases over weeks or months and will continue to worsen if not treated. When lockjaw does not occur until one year after treatment, it is usually permanent.
Maxillectomy, which is the removal of all or part of the upper jaw bone bone, is one possible cause of lockjaw in people with head and neck cancer. Maxillectomy causes scar tissue and inflammation, which can restrict movement. For those having a maxillectomy, people who require postoperative radiation are most at risk, according to the book “Complications in Head and Neck Surgery (Second Edition).”
Lockjaw can also be caused by muscle atrophy, or lack of use. After cancer treatment, the head and neck area may be immobilized (held still) for an extended time to allow healing. You may receive food via a feeding tube or be restricted to a liquid diet. Without consistent movement during this time, the muscles and tendons may stiffen and become difficult to move. This can also delay treatment of the lockjaw because when the muscles are not used, you might not realize that the problem is even occurring. You may not notice it until you can’t open your mouth.
Treatment for lockjaw
Early detection and treatment of lockjaw is important. Doctors often use the three-finger test to help diagnose this problem, according to Memorial Sloan Kettering Cancer Center. You should be able to fit three fingers between your teeth when opening your mouth. If you cannot, you are considered to have lockjaw.
There are several options for treating lockjaw in people with head and neck cancer, according to a 2016 systematic review. These options include:
- Physical therapy: Different exercises can be done in physical therapy to help treat lockjaw. Physical therapy can be done alone or in combination with other treatments. For some people, lockjaw is reversible with stretching exercises, especially when stretching begins within weeks of surgery or radiation.
- Jaw stretching device: Devices can be inserted between the upper and lower jaw to help stretch the muscles and treat lockjaw. There are several devices that can be used for this purpose, ranging in cost. For example, stacked tongue depressors may be used, but there are also devices specially designed for this purpose (which may be covered by your insurance). One such device that studies have shown to be effective is called the Therabite Jaw Motion Rehabilitation System. When used early, it can improve speech and swallowing and increase the range of motion in the jaw.
- Medications: Your doctor may prescribe certain drugs to help treat lockjaw, from pain relievers to muscle relaxants.
- Surgery: A procedure called coronoidectomy may be done to provide better range of motion.
How to prevent lockjaw
Anyone undergoing treatment for head and neck cancers can practice prevention measures to reduce their risk of developing lockjaw, according to Memorial Sloan Kettering Cancer Center. Some prevention measures include:
- Massaging jaw muscles
- Exercising jaw muscles
- Maintaining good posture
- Maintaining good oral hygiene
You should do these things even if you don’t have any symptoms or pain. Talk to your doctor to discuss other ways you can help prevent or treat this complication.