Changes in blood flow and cellular metabolism at a myofascial trigger point with trigger point release (ischemic compression): a proof-of-principle pilot study.

OBJECTIVE

To demonstrate proof-of-principle measurement for physiologic change within an active myofascial trigger point (MTrP) undergoing trigger point release (ischemic compression).

DESIGN

Interstitial fluid was sampled continuously at a trigger point before and after intervention.

SETTING

A biomedical research clinic at a university hospital.

PARTICIPANTS

Subjects (N=2) from a pain clinic who had chronic headache pain.

INTERVENTIONS

A single microdialysis catheter was inserted into an active MTrP of the upper trapezius to allow for continuous sampling of interstitial fluid before and after application of trigger point therapy by a massage therapist.

MAIN OUTCOME MEASURES

Procedural success, pain tolerance, feasibility of intervention during sample collection, and determination of physiologically relevant values for local blood flow as well as glucose and lactate concentrations.

RESULTS

Both patients tolerated the microdialysis probe insertion into the MTrP and treatment intervention without complication. Glucose and lactate concentrations were measured in the physiologic range. After intervention, a sustained increase in lactate was noted for both subjects.

CONCLUSIONS

Identifying physiologic constituents of MTrPs after intervention is an important step toward understanding pathophysiology and resolution of myofascial pain. The present study forwards that aim by showing that proof-of-concept for collection of interstitial fluid from an MTrP before and after intervention can be accomplished using microdialysis, thus providing methodological insight toward treatment mechanism and pain resolution. Of the biomarkers measured in this study, lactate may be the most relevant for detection and treatment of abnormalities in the MTrP.