Article

OBJECTIVES: To investigate the effect of painful stimulation of latent myofascial
trigger points (MTrPs) on skin blood flow and to evaluate the relative
sensitivity of laser Doppler flowmetry (LDF) and thermography in the measurement
of skin blood flow. DESIGN: Painful stimulation was obtained by a bolus injection
of glutamate (0.1mL, 0.5M) into a latent MTrP located in the right or left
brachioradialis muscles. A bolus of glutamate injection into a non-MTrP served as
control. Pain intensity (visual analog scale [VAS]) was assessed after glutamate
injection. Pressure pain threshold (PPT) was recorded bilaterally in the
brachioradialis muscle before and after glutamate-induced pain. Skin blood flow
and surface skin temperature were measured bilaterally in the forearms before,
during, and after glutamate-induced pain with LDF and thermography. SETTING: A
biomedical research facility. PARTICIPANTS: Fifteen healthy volunteer subjects.
INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: VAS, PPT, skin blood flow,
and surface skin temperature. RESULTS: Glutamate injection into latent MTrPs
induced higher pain intensity (F=7.16; P<.05) and lower PPT (F=11.41, P<.005)
than into non-MTrPs. Glutamate injection into non-MTrPs increased skin blood flow
bilaterally in the forearms, but skin blood flow after glutamate injection into
latent MTrPs was significantly less increased at the local injection area or
decreased at distant areas compared with non-MTrPs (all P<.05). Skin temperature
was not affected after glutamate injection into either latent MTrPs or non-MTrPs
(all P>.05). CONCLUSIONS: The present study demonstrated an attenuated skin blood
flow response after painful stimulation of latent MTrPs compared with non-MTrPs,
suggesting increased sympathetic vasoconstriction activity at latent MTrPs.
Additionally, LDF was more sensitive than thermography in the detection of the
changes in skin blood flow after intramuscular nociceptive stimulation.

Langue : ANGLAIS