What is the mechanism of action for the inactivation of trigger points by injection?

Updated: Nov 03, 2020
  • Author: Stephen Kishner, MD, MHA; Chief Editor: Erik D Schraga, MD  more...
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Answer

Several mechanisms have been suggested as possible explanations for the inactivation of trigger points by injection, including disruption of abnormal muscle fibers or nerve endings that make up the sensory and motor aspects of the feedback loop, which may be responsible for trigger point activity. Needling may cause a local release of intracellular potassium, which may depolarize and thus disrupt nerve conduction.

Injected fluid may dilute any nerve-sensitizing substances to reduce irritability and inactivate any neural feedback mechanisms. Procaine has a local vasodilatation effect that increases circulation at the trigger point, increasing the local removal of metabolites and increasing local energy supply. Further, a local anesthetic may interrupt feedback mechanisms between the trigger point and the central nervous system, limiting high frequency discharges transmitted by the nerve. Depending on the anesthetic, focal necrosis may destroy the trigger point. [5]


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