The hypoalgesic effect of remote tactile sensory modulation on the mechanical sensitivity of trigger points: A randomized controlled study

BACKGROUND: Sensitivity of the myofascial trigger point (MTrP) can be inhibited by electrical stimulation of remote site. However, it remains unclear whether remote pain control of the MTrP occurs in the same spinal segment or in the supraspinal system. OBJECTIVES: The aims of this study were to identify whether the remote pain control occurs in the spinal segment corresponding to the MTrP or in the supraspinal system.

METHODS: Test subjects (n = 10) received transcutaneous electrical nerve stimulation for 5 minutes, whereas control subjects (n = 10) received no intervention. The threshold for tactile sensory modulation at the lateral elbow was assessed using Von Frey filaments. The pressure sensitivities of MTrPs in both the infraspinatus and upper trapezius muscles were quantified by algometry. Measurements were performed at baseline and 1 and 15 minutes after the intervention. RESULTS: Increases of the tactile threshold at the remote site decreased the sensitivity of the MTrP innervated by same spinal segment. However, no changes were observed at MTrP sites innervated by contralateral fibers or those from different spinal segment. CONCLUSION: MTrP sensitivity is more strongly affected by interventions at remote ipsilateral sites in the same spinal segment than by stimulation of extra-segmental sites.