American Society of Regional Anesthesia and Pain Medicine February 2018 - 44

In one study, subjects were classified into active (neck pain with
MTrP), latent (no neck pain, MTrP present), and normal (no neck
pain, no MTrP) groups. Results showed that active MTrPs had
acidic pH levels, elevated catecholamines (norepinephrine and
serotonin), elevated neuropeptides (substance P [SP] and calcitonin
gene-regulated peptide [CRGP]), and elevated cytokines (TNF-a,
IL-6, and IL-8) as compared to the latent MTrP and normal groups.
After dry needling in the active group, SP and CGRP concentrations
were significantly lower than before dry needling. This may be
because of increased local blood flow, leading to a washout of pain
and inflammatory mediators.14 Continuous activation of muscle
nociceptors by local release of pain mediators from muscle injury
and inflammation can induce neuroplastic changes and central
sensitization by causing transcriptional changes on the cellular
level, leading to hypersensitivity and hyperexcitability.15
SUMMARY
It is important to understand the pathophysiology of myofascial pain
because it is common and distinct entity from other musculoskeletal
disorders and is treated differently than other disorders. Studies
have confirmed the presence of elevated levels of inflammatory
and pain mediators in MTrPs that are not found in normal muscles,
supporting the integrated trigger point hypothesis in which an
energy crisis and local hypoxic conditions contribute to release
of inflammatory and pain mediators that sensitize peripheral
nociceptors, leading to central sensitization and pain.

3.

Bubnov, V. Evidence-based pain management: is the concept of integrative
medicine applicable? EPMA J. 2012;3(1):13. doi: 10.1186/1878-5085-3-13.

4.

Simons DG. Muscle pain syndromes-part 1. Am J Phys Med. 1975;54:289-
311.

5.

Osterwies M, Kleinman A, Mechanic D, eds. Pain and Disability: Clinical,
Behavioral, and Public Policy Perspectives. Washington, DC: The National
Academies Press; 1987. Available at: https://doi.org/10.17226/991. Accessed
October 22, 2017.

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Borg-Stein J, Simons DG. Focused review: myofascial pain. Arch Phys Med
Rehabil. 2002;83(3 suppl 1):S40-S47, S48-S49.

7.

Simons DG, Travell JG, Simons L. Myofascial Pain and Dysfunction: The Trigger
Point Manual. Philadelphia, PA: Lippincott Williams & Wilkins; 1999.

8.

Mense S, Simons DG. Muscle Pain: Understanding Its Nature, Diagnosis, and
Treatment. Philadelphia, PA: Lippincott Williams & Wilkins; 2001.

9.

Hagg G. Ny forklaringsmodell for muskelskador vid statisk belastnin i skuldra
och nacke [in Swedish; New explanation for muscle damage as a result of
static loads in the neck and shoulder]. Arbete Manniska Miljo. 1988;4:
260-262.

10. Treaster D, Marras WS, Burr D, Sheedy JE, Hart D. Myofascial trigger point
development from visual and postural stressors during computer work. J
Electromyogr Kinesiol. 2006;16:115-124. doi: 10.1016/j.jelekin.2005.06.016.
11. Hubbard DR, Berkoff GM. Myofascial trigger points show spontaneous needle
EMG activity. Spine. 1993;18:1803-1807.
12. Huguenin LK. Myofascial trigger points: the current evidence. Phys Ther Sport.
2004;5:2-12. doi: 10.1016/j.ptsp.2003.11.002.
13. Willard F. Basic mechanisms of pain. In: Audette JF, Bailey A, eds. Integrative
Pain Medicine: The Science and Practice of Complementary and Alternative
Medicine in Pain Management. New York, NY: Humana Press; 2008:19-61.

1.

Guillaume de Baillou (1538-1616) clinician and epidemiologist. JAMA.
1966;195(11):957.

14. Shah JP, Gilliams, EA. Uncovering the biochemical milieu of myofascial trigger
points using in vivo microdialysis: an application of muscle pain concepts
to myofascial pain syndrome. J Bodyw Mov Ther. 2008;12:371-384. doi:
10.1016/j.jbmt.2008.06.006.

2.

Shah JP, Thaker N, Heimur J, et al. Myofascial trigger points then and now: a
historical and scientific perspective. PM R. 2015;7:746-761. doi: 10.1016/j.
pmrj. 2015.01.024.

15. Wall PD, Woolf CJ. Muscle but not cutaneous C-afferent input produces
prolonged increases in the excitability of the flexion reflex in the rat. J Physiol.
1984;356:443-458.

REFERENCES

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American Society of Regional Anesthesia and Pain Medicine
2018
https://www.doi.org/10.17226/991
Table of Contents for the Digital Edition of American Society of Regional Anesthesia and Pain Medicine February 2018
