Trigger point injection (TPI) may be an option in treating pain for some patients. 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. Many times, such knots can be felt under the skin. Trigger points may irritate the nerves around them and cause referred pain, or pain that is felt in another part of the body.
What Happens During a Trigger Point Injection?
In the TPI procedure, a health care professional 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 doctor’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.
When Is Trigger Point Injection Used?
TPI is used to treat many muscle groups, 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 involving tissue that surrounds muscle) that does not respond to other treatments. However, the effectiveness of TPI for treating myofascial pain is still under study.
