Diagnostic criteria of myofascial pain caused by trigger points

Objectives: To summarize the newly recognized pathophysiology of myofascial trigger points [MTrPs], to note three new and promising techniques for identifying TrPs, and to consider possible clinical diagnostic criteria in the light of the pathophysiology of MTrPs, Nature of Trigger Points: The core features of MTrPs are identified electrophysiologically by characteristic spontaneous electrical activity and histologically by contraction knots. Both phenomena apparently result from excessive release of the neurotransmitter acetylcholine from the nerve terminal of the motor endplate, This relationship identifies MTrPs as a neuromuscular disease. Diagnostic Criteria: Three recently identified objective confirmatory findings of MTrPs include: the electromyographic recording and ultrasound imaging of local twitch responses, the spontaneous electrical activity of multiple active loci in the MTrP, and biopsies of MTrPs that show contraction knots and giant round muscle fibers. Many of the clinical characteristics of MTrPs can be accounted for by their pathophysiology. Conclusion: The endplate dysfunction characteristic of MTrPs involves both the nerve terminal and the postjunctional muscle fiber. This relationship identifies MTrPs as a neuromuscular disease. Official diagnostic criteria should take this into consideration.