Acupuncture Mechanisms for Clinically Relevant Long-Term Effects – Reconsideration and a Hypothesis

Abstract

From the author's direct involvement in clinical research, the conclusion has been drawn that clinically relevant long-term pain relieving effects of acupuncture (>6 months) can be seen in a proportion of patients with nociceptive pain. The mechanisms behind such effects are considered in this paper. From the existing experimental data some important conclusions can be drawn: Much of the animal research only represents short-term hypoalgesia probably induced by the mechanisms behind stress-induced analgesia (SIA) and the activation of diffuse noxious inhibitory control (DNIC). Almost all experimental acupuncture research has been performed with electro-acupuncture (EA) even though therapeutic acupuncture is mostly gentle manual acupuncture (MA). Most of the experimental human acupuncture pain threshold (PT) research shows only fast and very short-term hypoalgesia, and, importantly, PT elevation in humans does not predict the clinical outcome. The effects of acupuncture may be divided into two main components – acupuncture analgesia and therapeutic acupuncture. A hypothesis on the mechanisms of therapeutic acupuncture will include: Peripheral events that might improve tissue healing and give rise to local pain relief through axon reflexes, the release of neuropeptides with trophic effects, dichotomising nerve fibres and local endorphins. Spinal mechanisms, for example, gate-control, long-term depression, propriospinal inhibition and the balance between long-term depression and long-term potentiation. Supraspinal mechanisms through the descending pain inhibitory system, DNIC, the sympathetic nervous system and the HPA-axis. Is oxytocin also involved in the long-term effects? Cortical, psychological, “placebo” mechanisms from counselling, reassurance and anxiety reduction.

The use of surface electromyography for the study of auricular acupuncture

“…Advances in the knowledge of neurophysiology have made it possible to establish that this is a neural peripheral stimulation method that promotes local and systemic reflexive responses, mediated by endocrine and immune systems and by superior centers of central control (Mayer, 2000;Carlsson, 2002).…”

Use of Acupuncture as a Treatment Method for Chronic Prostatitis/Chronic Pelvic Pain Syndromes

“…The inhibition would work fast and be short term, with effects occurring mainly during stimulation [27]. Propriospinal neurons may be activated by afferent stimulation or by supraspinal pathways [27,28]. With superperfusion techniques, it has been shown that axons from thoracic, cervical, or sacral levels can induce a lumbar antinociceptive effect.…”

“…The efficacy of this propriospinal inhibition was shown to be similar to the inhibition produced by stimulation of the periaqueductal grey (PAG). Thus, the propriospinal antinociceptive neurons may constitute a third component of endogenous antinociception in addition to segmental and supraspinal descending inhibition [27].…”

“…This mechanism was proposed to be under supraspinal control. The inhibition would work fast and be short term, with effects occurring mainly during stimulation [27]. Propriospinal neurons may be activated by afferent stimulation or by supraspinal pathways [27,28].…”

Mechanisms of acupuncture analgesia: Effective therapy for musculoskeletal pain?

“…However, additional studies of true and sham AP are required to clearly dissociate between specific and nonspecific placebo or nocebo effects. Spinal gating, stress-induced analgesia, and diffuse noxious inhibitory control may be responsible for short-term analgesic effects [48].…”