This information will help you prevent trismus during and after your radiation therapy.

Your jaw is made up of a pair of bones that form the framework of your mouth and teeth (see Figure 1). Your upper jaw is called the maxilla and your lower jaw is called the mandible. Your mandible connects to your skull at the temporomandibular joint (TMJ).

Figure 1 Figure 1

Many muscles and nerves around the jaw work together to open and close your mouth. Most people are able to open their mouth 35 to 55 millimeters, which is about the the width of 3 fingers (see Figure 2).

Figure 2 Figure 2

Trismus

Trismus is a condition in which someone has difficulty opening their mouth. Trismus can develop:

  • If a tumor involves the muscles and nerves that open the mouth
  • After surgery to the head and neck
  • After radiation therapy to the head and neck

Surgery and radiation therapy can injure the tissues involved in opening the mouth. Fibrosis (scarring) can develop as the tissues begin to heal from surgery. Fibrosis can also build up years after radiation therapy. Muscle and other fibers shorten and tighten, which makes it harder to open your mouth. When you can't open your mouth well, it is hard for your doctor to examine this area. You may also have problems:

  • Cleaning your mouth and teeth. This may lead to bad breath, cavities, and infections
  • Chewing and swallowing. This can make it difficult for you to eat and drink
  • Talking
  • Kissing
  • Having a breathing tube placed, if you ever need general anesthesia (medication to make you sleep during a surgery or procedure)
  • Having routine dental treatment

Once trismus develops, it is very hard to treat. Prevention and early treatment are the goals.

How to Prevent Trismus

There are 4 ways to help prevent trismus. Even if you don't have any symptoms, you should do the following to prevent problems:

  • Massage your jaw muscles
  • Exercise your jaw muscles
  • Maintain good posture
  • Maintain good oral hygiene

There are a number of exercises described below. During the exercises, breathe normally and do not hold your breath. If any of these exercises cause pain, numbness, or tingling, stop them right away and call your doctor or nurse. If you have had surgery, check with your doctor or nurse before you begin these exercises.

Massage Your Jaw Muscles (Masseter Muscle)

Figure 3 Figure 3 Place your index and middle finger on your cheek bone. Run your fingers down over your masseter muscle, which ends at your bottom jaw (see Figure 3). As you move your fingers, find points that feel tender or tight. Massage these areas with your fingers in a circular direction for 30 seconds.

To keep your jaw muscles relaxed all the time, avoid clenching your jaw when stressed or out of habit.

Exercise Your Jaw Muscles

Use a mirror for these exercises to help you do them correctly. These movements should give you a good stretch, but not cause pain.

Active range of motion and stretching exercises

Sit or stand. Hold your head still while doing these exercises.

  • Open your mouth as wide as you can, until you can feel a good stretch but no pain. Hold this stretch for ____ seconds (see Figure 4).

Figure 4 Figure 4

  • Move your jaw to the left. Hold this stretch for 3 seconds (see Figure 5).

Figure 5 Figure 5

  • Move your jaw to the right. Hold this stretch for 3 seconds (see Figure 6).

Figure 6 Figure 6

  • Move your jaw in a circle. Make 5 circles in each direction.

Passive stretching exercise

  • Place 1 thumb on your top teeth in the middle of your jaw. 
  • Place the pointer (index) finger of your other hand on your bottom teeth, in the middle of your jaw.
  • Open your mouth with your fingers, but do not bite down or resist. Let your fingers do all of the work. Hold this stretch for ___  seconds (see Figure 7).

Figure 7 Figure 7

Maintain Good Posture

Good posture means sitting and standing with your ears, shoulders, hips, knees, and ankles aligned. To maintain good posture, you need to keep your neck and shoulders strong and flexible (see Figure 8). The exercises listed below will help you do this. Do these exercises twice a day.

Figure 8 Figure 8

Neck stretch

Sit or stand with your arms at your side. Hold each stretch for 30 seconds.

  1. Bend your head down (see Figure 9).

Figure 9 Figure 9

  1. Extend your head backwards (see Figure 10).

Figure 10 Figure 10

  1. Rotate your head to the right (see Figure 11).

Figure 11 Figure 11

  1. Rotate your head to the left (see Figure 12).

Figure 12 Figure 12

  1. Bring your left ear to your left shoulder (see Figure 13).

Figure 13 Figure 13

  1. Bring your right ear to your right shoulder (see Figure 14).

Figure 14 Figure 14

Chin tuck

  1. Figure 15 Figure 15 Sit or stand with your arms at your side. 
  2. While looking forward, tuck your chin.
  3. Pull your head back to line up your ears with your shoulders. Hold this position for 3 seconds.
  4. Do this exercise 10 times slowly (see Figure 15).

Shoulder blade pinch

Sit or stand with your arms at your side. Tuck your chin, as described above. Pinch your shoulder blades together as tightly as possible. Hold this position for 3 seconds. Do this exercise 10 times slowly (see Figure 16).

Figure 16 Figure 16

Maintain Good Oral Hygiene

  • Brush your teeth and tongue after each meal and at bedtime.

  • If you have removable dentures or a dental prosthesis, take it out and clean it each time you clean your mouth. Do not sleep with these devices in your mouth.

  • Floss your teeth once daily at bedtime.

If You Develop Tightness When Opening Your Mouth

Remember, trismus can occur anytime during, right after, or even years after your treatment. The earlier you start treatment for trismus, the easier it will be to restore your jaw function. If you notice any tightening in your jaw, call your doctor or nurse right away. They can refer you to:

  • Speech/swallowing specialists and physical therapists. They can help you maintain and restore your ability to open your mouth. They use many techniques, such as exercise, stretching, and massage. They may also recommend special devices to help you open your mouth.

  • Rehabilitation doctors. They will evaluate how well you can open your mouth. They may give you  medication for pain or spasms or suggest other treatments to help you.