Current research on myofascial trigger points - Pathophysiological studies

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 charact eristically exhibits a sensory component [sensitive locus] and a motor comp onent [active locus]. A sensitive locus is the site from which spot tendern ess, referred pain [ReP], and local twitch response [LTR] can be elicited b y 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 electrica l activity [SEA] can be recorded, Active loci are dysfunctional endplates, since SEA is essentially the same as electrical activity recorded from an a bnormal 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 an d LTR are mediated through spinal cord mechanisms, demonstrated in both hum an and animal studies, Conclusions: The pathogenesis of MTrPs appears to involve serious disturban ce of the nerve ending and contractile mechanism at multiple dysfunctional endplates.