Trigger Point Injections

Abstract

Myofascial pain syndrome, which is caused by myofascial trigger points, is a very common muscular disorder. Myofascial trigger points (MTrPs) are defined as the most tender (hyperirritable) foci in a palpable taut band of skeletal muscle fiber that can elicit pain, referred pain, a local twitch response (LTR), motor dysfunction, as well as autonomic phenomena, among other symptoms. MTrPs can develop secondary to overextension of a muscle, acute trauma, or repetitive microtrauma. The pathophysiology of the development of MTrPs can be explained using the integrated hypothesis. This hypothesis has three essential features that include excessive acetylcholine release, sarcomere shortening, and the release of sensitizing substances. The most common way in which trigger points are localized is through a proper history and physical exam. Trigger point injections are specific techniques aimed at the alleviation of pain located within the MTrP. Whether an agent is injected into the MTrP or dry needling is performed, both techniques disrupt the trigger point by causing the relaxation and lengthening of the involved muscle fibers. Trigger point injections are generally very safe, but like all procedures, certain precautions must be taken into consideration.