PATHOPHYSIOLOGIC AND ELECTROPHYSIOLOGIC MECHANISMS OF MYOFASCIAL TRIGGER POINTS

Objective: To review recent clinical and basic science studies on myof ascial trigger points (MTrPs) to facilitate a better understanding of the mechanism of an MTrP. Data Sources: English literature in the last 15 years regard ing scientific investigations on MTrPs in either huma ns or animals. Study Selection: Research works, especially electrophys iologic studies, related to the pathophysiology of MTrP. Data Synthesi s: (1) Studies on an animal model have found that a myofascial trigger spot (MTrS) in a taut band of rabbit skeletal muscle fibers is simila r to a human MTrP in many aspects. (2) An MTrP or an MTrS contains mul tiple minute loci that are closely related to nerve fibers and motor e ndplates. (3) Both referred pain and local twitch response (characteri stics of MTrPs) are related to the spinal cord mechanism. (4) The taut band of skeletal muscle fibers (which contains an MTrP or an MTrS in the endplate zone) is probably related to excessive release of acetylc holine in abnormal endplates. Conclusion: The pathogenesis of an MTrP appears to be related to integrative mechanisms in the spinal cord in response to sensitized nerve fibers associated with abnormal endplates . (C) 1998 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.