Trismus causes painful spasms in the muscles that surround your jaw joints (temporomandibular joints). Several conditions and issues may cause trismus. It may be a side effect of head and neck cancer treatment or happen after dental surgery. Some infections or being hit in your jaw may cause trismus. Healthcare providers treat trismus with medication and physical therapy.
When your jaw muscles become so tight that you can’t open your mouth, you may have a condition known as trismus. Trismus refers to muscle spasms in your temporomandibular joint. Head and neck cancer treatment is the most common reason why people develop trismus. Healthcare providers treat trismus with medication and physical therapy.
Normally, your mouth opening measures 40 to 60 millimeters. (Depending on the size of your hand and fingers, that equals the width of two or three fingers held together.) If you have trismus, you may not be able to open your mouth wider than 20 to 35 millimeters. This may keep you from eating or speaking. Most trismus symptoms go away in a few weeks. Some people with chronic or long-lasting trismus may develop depression.
Many people can develop trismus, but the condition typically affects the following groups:
The conditions share several symptoms. Like trismus, tetanus makes it hard for you to open your mouth and can be very painful. The difference is trismus happens because something affected your jaw, like cancer treatment or having your wisdom teeth removed. Tetanus (lockjaw) is a bacterial infection that may cause muscle spasms throughout your body.
The most common symptom is not being able to open your mouth as wide as usual. Other symptoms include:
Trismus is linked to a long list of conditions and medical issues. The most common causes are TMD, reaction to head and neck cancer treatment or after wisdom teeth removal. Other causes include:
Healthcare providers diagnose trismus by asking about your symptoms and examining your jaw, neck and temporomandibular joint.
Healthcare providers start by treating any underlying cause. For example, if you can’t open your mouth because you have an infected (abscessed) tooth, your healthcare provider may give you antibiotics or remove the infected tooth. Other possible treatments are:
Depending on the situation, including treatment for underlying causes, most people feel better within a few weeks.
Trismus typically affects people who’ve had treatment for head and neck cancer. Medical researchers are studying ways to ease post-treatment trismus.
Your prognosis, or expected outcome, depends on the condition’s cause. People who have trismus after cancer treatment may have symptoms for a long time. They may need long-term physical therapy.
A note from Cleveland Clinic
Most people develop trismus after treatment for head and neck cancer. Overall, jaw spasms may seem like a minor issue compared with cancer and cancer treatment side effects. But left untreated, trismus can affect people’s ability to eat and regain strength after treatment. It can affect their ability to communicate, making them feel frustrated or isolated. If cancer treatment makes it hard for you to open your mouth, let your healthcare provider know. They’ll recommend treatment to ease your symptoms.
Last reviewed by a Cleveland Clinic medical professional on 08/29/2022.
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