Dryneedling—peripheralandcentralconsiderations

Myofascial pain syndrome and trigger points represent a significant source of musculoskeletal pain that affects millions of people worldwide. Despite their prevalence, popular explanations of myofascial pain have often been overly simplistic, failing to provide clinicians with a robust theoretical foundation for treatment. Historically, researchers and clinicians relied on concepts like the pain–spasm–pain cycle, which suggested that muscle pain caused spasm in the same muscle, leading to a vicious cycle of increasing pain. However, this concept has been refuted by modern research showing that nociceptive input generally inhibits rather than excites motor neurons.

The field needed an updated framework that integrates contemporary pain science with clinical practice. Dry needling, a technique increasingly used by physical therapists and other healthcare providers, required placement within this broader context of pain mechanisms to optimize its application and understand its effects beyond simple local tissue changes.

This narrative review synthesizes existing research on myofascial trigger points and dry needling from a pain science perspective. The author examined multiple domains of evidence including the neurophysiology of trigger point formation, the differences between active and latent trigger points, motor adaptation theories, mechanisms of peripheral and central sensitization, and the clinical effects of dry needling. The review draws upon animal studies, human experimental research, biochemical analyses using microdialysis, imaging studies, and clinical trials. The author critically evaluates different schools of dry needling, including trigger point dry needling, intramuscular stimulation, and integrative systemic dry needling, assessing their theoretical foundations and evidence bases.

The review also addresses the relationship between dry needling and acupuncture, including scope of practice considerations and the challenges of designing placebo-controlled studies for needling interventions.

The review establishes that trigger points are not merely local muscle phenomena but constant sources of peripheral nociceptive input that drive both peripheral and central sensitization. Active trigger points feature significantly lower pain thresholds with electrical stimulation compared to latent trigger points and normal muscle tissue. The immediate biochemical environment of active trigger points shows elevated levels of substance P, CGRP, bradykinin, serotonin, norepinephrine, tumor necrosis factor-alpha, and interleukin-1beta compared to latent trigger points and normal muscle. The pH in active trigger points may fall below 5, sufficient to excite muscle nociceptors and activate acid-sensing ion channels.

Latent trigger points, while not spontaneously painful, provide ongoing nociceptive input into the dorsal horn and can quickly become active through central sensitization. The formation of taut bands involves excessive acetylcholine release at motor endplates combined with acetylcholine esterase inhibition. Endplate noise correlates with trigger point irritability, and botulinum toxin reduces this activity.

Dry needling produces multiple measurable effects: immediate reduction in local and referred pain, restoration of range of motion and muscle activation patterns, normalization of the chemical environment at trigger points, and reduction of peripheral and central sensitization. After eliciting a local twitch response, substance P and CGRP are significantly reduced in active trigger points. Dry needling can reduce endplate noise not only at treated trigger points but also at remote trigger points. In one study of knee replacement patients, dry needling under anesthesia produced significantly lower postoperative pain and reduced analgesic requirements.

A Cochrane review concluded that dry needling appears to be a useful adjunct for chronic low back pain.

The review highlights the difficulty of designing true placebo-controlled studies for needling, as even sham procedures like superficial needling or skin tapping produce physiological effects. The Streitberger needle, which retracts without penetrating, represents one approach but expectancy effects still influence outcomes through prefrontal and anterior cingulate cortex activation.

For clinicians, this review emphasizes that effective dry needling requires understanding trigger points within a comprehensive pain science framework rather than as isolated muscle problems. Treatment should be based on thorough assessment of peripheral and central sensitization, motor adaptation patterns, and the full clinical picture. Dry needling should not be viewed as a standalone intervention but as one component of comprehensive manual physical therapy, combined with other manual techniques, exercise, and patient education.

The evidence supports targeting both active and latent trigger points, as latent points contribute to ongoing nociceptive input and can become active. The review suggests that addressing trigger points before surgical procedures may improve outcomes by reducing pre-existing central sensitization. For patients with chronic pain conditions including fibromyalgia, whiplash, temporomandibular disorders, and tension-type headaches, trigger point dry needling may help by removing a constant peripheral nociceptive source that maintains central sensitization.

The review also clarifies professional boundaries, noting that dry needling is within the scope of multiple disciplines including physical therapy and acupuncture, with overlap being both inevitable and potentially beneficial for patient care. However, proper training in anatomy, physiology, and pain sciences remains essential for safe and effective practice.