Microdialysis Evaluation of Blood Flow, Lactate, and Glucose in Active Trigger Points of Tension-Type Headache Patients and Latent Trigger Points in Healthy Muscle.

OBJECTIVE

To assess nutritive blood flow, lactate, and glucose within active and latent trigger points (TrPs) compared with non-TrP muscle.

DESIGN

Case-controlled observational study.

SETTING

A university-based clinical and translational research center.

PARTICIPANTS

Active TrPs were identified through palpation of the upper trapezius muscle of individuals with episodic or chronic tension-type headache (TTH). Latent TrPs and muscle without TrPs were identified in age- and sex-matched subjects without a history of headache. A total of 64 individuals participated in the study.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: Nutritive blood flow, and interstitial lactate and glucose concentrations were determined at 12-20 minutes intervals over 160 minutes through microdialysis sampling of interstitial fluid.

RESULTS

Subjects were 33.8±10.8 years, 64.1% women, and 73.4% white, with no statistical differences between active, latent, and no TrP groups on demographic or baseline variables (P>.05). Subjects with TTH reported a median of 4 headaches/mo and had experienced headaches for a median of 120 months. Active TrPs exhibit higher nutritive blood flow than anatomically matched no TrP muscle (P=.026) but were not different from latent TrPs (P=.554). There were no global differences between the 3 groups for lactate (P=.329) or glucose (P=.231).

CONCLUSIONS

This study provides in vivo evidence of higher nutritive blood flow in active TrPs from individuals with TTH but no difference in lactate and glucose compared with non-TrP muscle. Our data do not support the TrP as a tightly contracted, ischemic region within skeletal muscle. Interventions designed to relax muscle contraction or increase blood flow may have limited benefits in alleviating active trigger points.