The hypoalgesic effect of remote tactile sensory modulation on the mechanical sensitivity of trigger points

It is possible to inhibit the sensitivity of the myofascial trigger point (MTrP) by electrical stimulation of remote site. However, it is still not clear whether remote pain control of the MTrP occurs in the same spinal segment or in the supraspinal system. This study aimed to identify whether the remote pain control occurs in the spinal segment corresponding to the MTrP or in the supraspinal system. 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. Increases of the tactile threshold at the remote site decreased the sensitivity of the MTrP innervated by same spinal segment were observed. However, no changes were seen at MTrP sites innervated by contralateral fibers or those from different spinal segment.

MTrP sensitivity is more strongly influenced by interventions at remote ipsilateral sites in the same spinal segment than by stimulation of extra-segmental sites.