Probable Mechanisms of Needling Therapies for Myofascial Pain Control
Chou et al. · Evidence-Based Complementary and Alternative Medicine · 2012
Evidence Level
STRONGOBJECTIVE
To review the possible mechanisms of needling therapies (acupuncture and dry needling) in myofascial pain control
WHO
Patients with myofascial pain syndrome and myofascial trigger points
DURATION
Literature review through 2012
POINTS
Ah-Shi points, remote acupoints on meridian and extra-meridian pathways, myofascial trigger points
🔬 Study Design
Theoretical review
n=0
Analysis of mechanisms of action
📊 Results in numbers
Correlation between acupuncture points and trigger points
Anatomical correspondence
Clinical correspondence
Referred pain correspondence
Percentage highlights
📊 Outcome Comparison
Proposed mechanisms of action
This study explains how acupuncture and dry needling work to relieve muscle pain. The researchers found that these techniques activate several body systems, including the release of natural pain-relieving substances and modulation of the nervous system. This helps explain why these therapies can be effective for persistent muscle pain.
Article summary
Plain-language narrative summary
Myofascial pain syndrome is a common condition characterized by regional muscular pain caused by myofascial trigger points (MTrPs), defined as hypersensitive spots in taut bands of skeletal muscle fibers. This review study examines the probable mechanisms by which needling therapies, including trigger-point injection, dry needling, and acupuncture, effectively control myofascial pain. Acupuncture probably represents the first reported dry-needling technique in the treatment of patients with myofascial pain syndrome, based on the theory of Traditional Chinese Medicine. The mechanisms of acupuncture analgesia are complex and multifactorial, involving the immune, hormonal, and nervous systems.
The nervous system acts more rapidly compared with the slow hormonal system, but acupuncture analgesia cannot be explained by a single mechanism. Among the principal proposed mechanisms are: (1) the endogenous opioid theory (morphine-like substances), in which acupuncture induces the release of β-endorphin, enkephalin, endomorphin, and dynorphin; (2) descending pain inhibitory pathways mediated by serotonin, particularly through the nucleus raphe magnus; (3) anti-inflammatory mechanisms, in which acupuncture can reduce hyperalgesia associated with inflammation; and (4) the cholinergic anti-inflammatory pathway, which reflexively regulates the inflammatory response. The study reviews clinical and basic research evidence on dry needling and acupuncture for trigger points, highlighting the importance of the local twitch response during treatment. Animal research using myofascial sensitive-point models has demonstrated characteristics similar to human MTrPs, including pain, local twitch response, and spontaneous electrical activity.
Acupoint selection is based on Traditional Chinese Medicine principles, including "Ah-Shi" points (painful points), proximal or remote acupoints on the meridian, and extra-meridian points. Clinical studies show that needling at distant points can be effective for myofascial pain, suggesting remote effects mediated by spinal mechanisms. The correlation between acupoints and trigger points has been debated, with studies showing anatomical correspondence of 92%, clinical of 79.5%, and referred pain of 76%. The most likely mechanism for pain relief from needle stimulation is hyperstimulation analgesia via the descending pain inhibitory system, following the gate-control theory of pain by Melzack.
High-pressure stimulation at MTrP loci can provide strong neural impulses to dorsal horn cells in the spinal cord, breaking the vicious circle of the MTrP circuit. Biochemical research has confirmed that pain-, inflammation-, and intercellular signaling-associated substances are elevated near active MTrPs, differentiating them from latent ones. The remote effects of needling probably involve an intact afferent neural pathway from the site of stimulation to the spinal cord and normal spinal cord function at the level corresponding to the innervation of the affected muscle. This mechanism may be related to diffuse noxious inhibitory control induced by nociceptive stimulation applied to the painful region or to a remote site.
Limitations include the complexity of the mechanisms involved and the need for further research to fully elucidate the neural and biochemical pathways. Nevertheless, current evidence supports that myofascial pain is a complex form of neuromuscular dysfunction involving motor and sensory abnormalities in both the peripheral and central nervous systems, and that needling therapy can provide significant pain relief via well-grounded neural mechanisms.
Strengths
- 1Comprehensive review of multiple mechanisms of action
- 2Integration of clinical and experimental evidence
- 3Solid scientific basis to explain clinical efficacy
- 4Detailed analysis of anatomical correlations
Limitations
- 1Mechanisms not yet fully elucidated
- 2Need for further controlled studies
- 3Multifactorial complexity hinders isolation of effects
- 4Individual variability in mechanisms
Expert Commentary
Prof. Dr. Hong Jin Pai
PhD in Sciences, University of São Paulo
▸ Clinical Relevance
Myofascial pain syndrome is probably the most prevalent painful condition in the pain outpatient setting, and mechanistic clarity about how needling acts in this context directly transforms clinical decision-making. When we have a coherent pathophysiologic framework — involving endogenous opioid release, activation of descending serotonergic inhibitory pathways, and cholinergic anti-inflammatory modulation — we can select treatment candidates with greater precision and communicate the therapeutic rationale to the patient consistently. The distinction between active and latent trigger points, supported by measurable biochemical differences in the muscular microenvironment, guides both diagnosis and the choice of the needling target. Patients with regional myofascial pain refractory to conventional analgesics and physical therapy alone represent the clinical scenario in which this mechanistic basis translates into a concrete, well-grounded therapeutic strategy.
▸ Notable Findings
The 92% correspondence between acupoints and myofascial trigger points on the anatomical dimension — complemented by 79.5% clinical correspondence and 76% referred-pain correspondence — represents one of the most robust bridges ever documented between Traditional Chinese Medicine and Western functional anatomy. This figure is not trivial: it suggests that millennia of empirical mapping have converged, to a large extent, on the same structures that modern neurophysiology identifies as foci of neuromuscular dysfunction. Equally relevant is the proposal that the central mechanism of relief is hyperstimulation analgesia via diffuse noxious inhibitory control, explaining why needling at remote points can be effective — provided that the afferent pathway and spinal cord function at the corresponding segment are preserved. The local twitch response emerges, in this context, not as an epiphenomenon, but as a marker of effective therapeutic access to the trigger-point locus.
▸ From My Experience
At the Pain Center of HC-FMUSP (Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo), we have worked for decades with the premise that dry needling and acupuncture are not unrestrictedly interchangeable — and this review helps articulate why. In my practice, I have observed that patients with well-demarcated active trigger points, particularly in the trapezius, levator scapulae, and lumbar paravertebral musculature, tend to show perceptible response after just two or three sessions, provided that the local twitch response is obtained during the procedure. For consolidation and maintenance, we usually work with cycles of six to ten sessions, reassessing after each series. Combination with kinesiotherapy focused on eccentric stretching consistently potentiates and prolongs results. Patients with pronounced central sensitization, concomitant fibromyalgia, or high levels of catastrophizing respond more erratically, requiring a multimodal approach from the outset. The profile that responds best to isolated needling is the patient with well-localized regional myofascial pain, without diffuse painful comorbidity and with musculature still responsive to mechanical stimulation.
Full original article
Read the full scientific study
Evidence-Based Complementary and Alternative Medicine · 2012
DOI: 10.1155/2012/705327
Access original articleScientific Review
Marcus Yu Bin Pai, MD, PhD
CRM-SP: 158074 | RQE: 65523 · 65524 · 655241
PhD in Health Sciences, University of São Paulo. Board-certified in Pain Medicine, Physical Medicine and Rehabilitation, and Medical Acupuncture. Scientific review and curation of every entry in this library.
Learn more about the author →Medical disclaimer: This content is for educational purposes only and does not replace consultation, diagnosis, or treatment by a qualified professional. Some information may be assisted by artificial intelligence and is subject to inaccuracies. Always consult a physician.
Content reviewed by the medical team at CEIMEC — Integrated Centre for Chinese Medicine Studies, a reference in Medical Acupuncture for over 30 years.
Related articles
Based on this article’s categories