Trigger point injection (TPI) may be an option for treating pain in 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.
The benefits of trigger point injections last between a few days and months depending on patient condition and medication injected. Many patients receive a certain number of injections with a gap of one or two weeks. The gap increases and frequency gradually decreases with time.