What is trismus?
Trismus, also called lockjaw, is the inability to open the mouth normally. This can lead to difficulty eating, swallowing, speaking, and performing mouth care. It can also alter a person’s appearance. Trismus is caused by damage to the muscles and nerves that perform chewing or opening the jaw. In head and neck cancer patients, this can be caused by scar tissue or nerve damage from radiation or surgery. It affects anywhere from 10-40 percent of people treated for head and neck cancer.
When trismus is caused by radiation, is it usually associated with other side effects as well. 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 difficulty hearing.
How is trismus diagnosed?
The ability to open the jaw tends to decrease slowly over time with trismus related to head and neck cancer treatment. Treatment is most effective when started early in the course of the problem. One way to monitor for trismus is called the 3 finger test. Holding 3 fingers together, try to insert them vertically between the top and bottom teeth. If they cannot fit, there is likely some restriction of the jaw.
How is trismus treated?
Exercises to prevent trismus should start before radiation treatment and continue indefinitely. You will be taught how to perform exercises that maintain maximum opening of the jaw. These exercises should be done 3-4 times a day. How wide you can open your jaw will be measured before, during, and after treatment.
Physical therapy may use multiple tongue depressors bound together or devices such as TheraBite® and Dynasplint to exercise and stretch the muscles to restore mobility and flexibility.
Medications such as pain relievers, muscle relaxants, and anti-inflammatories can be used to help treat trismus. A soft diet can also be helpful.
Trismus can greatly affect your daily life and the best course of action is to start exercises prior to trismus developing. Your care team will discuss if you are at risk for developing trismus, provide prevention exercises, help you to manage this side effect, and to help you determine if your insurance will cover any treatment devices.
Healthline. Trismus. 2018. Found at: https://www.healthline.com/health/trismus
The Oral Cancer Foundation. Trismus. Found at: https://oralcancerfoundation.org/complications/trismus/