Trismus
(Reduced mouth opening)

Trismus is the term used to describe reduced mouth opening. If you have trismus you may have difficulty opening your mouth. You may also experience pain with chewing or talking. Trismus can occur due to the location of the cancer or as a result of cancer treatments, including surgery to remove the cancer or radiation therapy that is directed towards the jaw joint or saliva glands. 

Radiation therapy targeting this area can cause inflammation and tightening of the muscles and ligaments around the jaw joint. This may be temporary and can resolve as the side effects improve after treatment has finished. However, in some cases trismus can be permanent and it can even occur months or even years after radiation therapy.

Trismus can affect how you:

• Open your mouth, bite, chew & eat

• Open your mouth to clean your teeth or have a dental review

• Speak

• Yawn

• Laugh

A simple way to test for trismus is to insert 3 fingers (index, middle, and ring fingers) into your mouth. If you cannot ‘stack’ 3 fingers between your upper and lower teeth, or dentures, you may have trismus. You may also have trismus if you have a feeling of tightness when you open your mouth.

If you have trismus, a speech pathologist can assess your jaw movement and give you stretching exercises to help you maintain or improve the opening of your mouth. They can monitor your progress with exercises and modify them if required. Research has shown that some cancers are more likely to result in trismus than others. For these types of cancers, a speech pathologist will provide you with jaw stretches at the beginning of treatment, even if your jaw opening still feels normal, to help reduce the risk of developing trismus throughout treatment.  

If you are experiencing difficulty with jaw movement a referral for a Speech Pathology consultation can be obtained from our Oncology Nurses.

Page reviewed 6th July 2021