Trigger point injection (TPI) is a procedure used to treat painful areas of muscle that contain trigger points, or knots of muscle that form when muscles do not relax. Trigger points may irritate the nerves around them and cause referred pain that is felt in another part of the body.
A physician inserts a small needle into the patient’s trigger point. The injection contains a local anesthetic that sometimes includes a corticosteroid. With the injection, the trigger point is made inactive and the pain is alleviated. Usually, a brief course of treatment will result in sustained relief.
Injections are given in a physician’s office and usually take just a few minutes. Several sites may be injected in one visit. If a patient has an allergy to a certain drug, a dry-needle technique (involving no medications) can be used.
Pain management physicians treat many muscle groups using TPI, especially those in the arms, legs, lower back, and neck. In addition, TPI can be used to treat fibromyalgia and tension headaches.
The technique is also used to alleviate myofascial pain syndrome (chronic pain in tissue that surrounds muscle) that does not respond to other treatments. However, the effectiveness of TPI for treating myofascial pain is still under study.