Trismus

Trismus (pronounced TRIZ-muhs) is a condition that causes your jaw muscles to become so tight that you can’t fully open your mouth. This is why some people call it “lockjaw.” It happens when you have spasms in the muscles surrounding your jaw joint. It’s called the temporomandibular joint (TMJ).

Most mouths open about 40 to 60 millimeters. (That equals about the width of two or three fingers held together.) But if you have trismus, you may not be able to open your mouth wider than 20 to 35 millimeters.

Several medical conditions can lead to trismus. But no matter the cause, it’s important to see your healthcare provider if you have symptoms. There are treatments that can loosen stiff jaw muscles.

Symptoms of trismus

The most common symptom is not being able to open your mouth as wide as usual. Other symptoms include:

• Jaw muscles that feel tight, as if you have cramps in your jaw
• Jaw pain when you’re moving your jaw and even when you aren’t
• Trouble opening your mouth wide enough to brush and floss your teeth

Trismus causes

Lots of medical issues can cause trismus. The main causes are head and neck cancer treatments, disorders affecting your jaw joint (TMD) and wisdom teeth removal. Other causes include:

• Inflammatory conditions: You may develop trismus if you have long-term swelling in your jaw.
• Infections: Diseases like mumps, tetanus and tonsillitis can trigger trismus. You may develop trismus if you have infections that affect your teeth, neck or parotid (salivary) gland.
• Trauma: You may develop trismus if your jaw is hit or injured. Sometimes, trismus happens after surgery on your mouth.

Risk factors

Anyone can develop trismus, but the condition typically affects:

• People with a disorder affecting their jaw joint (TMD): Trismus is a common TMD symptom.
• People with head and neck cancer: Tumors can cause trismus. Up to 4 out of 10 people who have radiation therapy for head and neck cancer develop trismus.
• Young adults who’ve had surgery to remove their lower wisdom teeth: Having your jaw held open wide during surgery can lead to trismus.

Complications of this condition

Trismus can increase your chances of:

• Aspiration: Trouble swallowing may cause food or liquid to go down your windpipe instead of your esophagus.
• Cavities and tooth infections: Being unable to open your mouth can make it hard to care for your teeth. This can lead to tooth decay and serious infections.
• Weight loss and malnutrition: Trouble eating can cause you to skip meals. But it’s important that you get enough calories and nutrients. This is especially the case if you’re getting cancer treatment.

Having trouble eating and talking can impact your mental health. Many people with trismus that lasts a while experience depression. This is why it’s important to get help from a healthcare provider if you have symptoms.

How doctors diagnose this condition

Your healthcare provider will diagnose trismus by asking about your symptoms and examining your jaw and neck. They may use the “three-finger test” to measure how wide you can open your mouth.

In some cases, you may need an imaging test, like a CT scan or MRI. Imaging can show the extent of tissue damage that’s causing issues.

How is it treated?

Healthcare providers start by treating the cause of the spasms or tightness. For example, if you can’t open your mouth because you have an infected tooth, your healthcare provider may give you antibiotics or remove it. Other possible treatments are:

• NSAIDs: You may need over-the-counter (OTC) or prescription NSAIDs to ease jaw pain.
• Muscle relaxers: These prescription medications ease muscle spasms.
• Physical therapy: A physical therapist may recommend exercises that stretch tight jaw muscles. They may use devices that gradually pull your jaw apart.
• Speech therapy: You may work with a speech-language pathologist. They can help you use your speaking and swallowing muscles more effectively.
• Surgery: You may need surgery to remove scar tissue in your jaw and reconstruct the tissue. This is more likely to happen if radiation therapy causes trismus.

How long does it take for trismus to heal?

With many causes, most people feel better within two weeks. Recovery is more complicated when cancer treatment causes trismus. Usually, trismus gets worse over several months after radiation before it gets better. According to one study, it may take several years to gradually regain jaw movement.

But most people who stick with physical therapy see improvements.

When should I see my healthcare provider?

Reach out to your provider as soon as possible if you’re experiencing symptoms of trismus. Early treatment can put you on the fast track to recovery.

What can I expect if I have trismus?

Your prognosis, or expected outcome, depends on the cause of the issue. For example, taking it easy on your jaw after wisdom tooth surgery is usually enough to fix trismus. It may take as little as a week to heal. Trismus after cancer treatment may cause symptoms for a long time. You may need long-term physical therapy.

Ask your healthcare provider what to expect based on your diagnosis and treatments.

Is there anything I can do to feel better?

To manage trismus at home:

• Avoid solid foods: Substitute hard-to-chew foods for soft foods or liquid meals. Make sure you’re getting enough calories each day.
• Do any prescribed exercises: Don’t skip any physical therapy exercises that your provider assigned to you.
• Rest your aching jaws: Everyday habits like biting your fingernails and chewing gum put stress on your tight jaw muscles. Try to avoid them.
• Take care of your teeth: Take your time brushing and flossing so that you’re cleaning your teeth as best as you can.
• Try homemade heat therapy: Wrap a moist hot towel around your jaw and neck and leave it for 15 to 20 minutes once an hour. The moist heat will help your muscles relax and possibly reduce muscle spasms.

What’s the difference between trismus and tetanus (lockjaw)?

Like trismus, tetanus makes it hard for you to open your mouth and can be very painful. But trismus has many causes. Tetanus is a bacterial infection that causes trismus — among other symptoms.

It can be confusing because people refer to both tetanus and trismus as “lockjaw.” This is because tetanus was the first condition doctors recognized as having lockjaw (trismus) as a defining feature.