To investigate the biochemical milieu of the upper trapezius muscle in subjects with
active, latent, or absent myofascial trigger points (MTPs) and to contrast this with
that of the noninvolved gastrocnemius muscle.
We used a microanalytic technique, including needle insertions at standardized locations
in subjects identified as active (having neck pain and MTP), latent (no neck pain
but with MTP), or normal (no neck pain, no MTP). We followed a predetermined sampling
schedule; first in the trapezius muscle and then in normal gastrocnemius muscle, to
measure pH, bradykinin, substance P, calcitonin gene-related peptide, tumor necrosis
factor alpha, interleukin 1beta (IL-1beta), IL-6, IL-8, serotonin, and norepinephrine,
using immunocapillary electrophoresis and capillary electrochromatography. Pressure
algometry was obtained. We compared analyte concentrations among groups with 2-way
repeated-measures analysis of variance.
A biomedical research facility.
Nine healthy volunteer subjects.
Preselected analyte concentrations.
Within the trapezius muscle, concentrations for all analytes were higher in active
subjects than in latent or normal subjects (P<.002); pH was lower (P<.03). At needle
insertion, analyte concentrations in the trapezius for the active group were always
higher (pH not different) than concentrations in the gastrocnemius muscle. At all
times within the gastrocnemius, the active group had higher concentrations of all
analytes than did subjects in the latent and normal groups (P<.05); pH was lower (P<.01).
We have shown the feasibility of continuous, in vivo recovery of small molecules from
soft tissue without harmful effects. Subjects with active MTPs in the trapezius muscle
have a biochemical milieu of selected inflammatory mediators, neuropeptides, cytokines,
and catecholamines different from subjects with latent or absent MTPs in their trapezius.
These concentrations also differ quantitatively from a remote, uninvolved site in
the gastrocnemius muscle. The milieu of the gastrocnemius in subjects with active
MTPs in the trapezius differs from subjects without active MTPs.