Current Research on Myofascial Trigger Points–Pathophysiological Studies

SUMMARY

Objectives: To summarize recent studies on myofascial trigger point [MTrP] to further clarify the mechanism of MTrP.

Methods: To review recent clinical and basic science studies related to the pathophysiology of MTrPs.

Results: There are multiple loci in an MTrP region. A clinical MTrP characteristically exhibits a sensory component [sensitive locus] and a motor component [active locus]. A sensitive locus is the site from which spot tenderness, referred pain [ReP], and local twitch response [LTR] can be elicited by mechanical stimulation. Sensitive loci [probably sensitized nociceptors] can be widely distributed in the whole muscle, but are concentrated in the endplate zone. An active locus is the site from which spontaneous electrical activity [SEA] can be recorded. Active loci are dysfunctional endplates, since SEA is essentially the same as electrical activity recorded from an abnormal endplate as reported by neurophysiologists. An MTrP is always found in a taut band which is histologically related to contraction knots caused by excessive release of acetylcholine in an abnormal endplate. Both ReP and LTR are mediated through spinal cord mechanisms, demonstrated in both human and animal studies.

Conclusions: The pathogenesis of MTrPs appears to involve serious disturbance of the nerve ending and contractile mechanism at multiple dysfunctional endplates.