Although acupuncture has been practiced for centuries with claimed benefits
to chronic pain, medical progress and western tradition have insisted on the
investigation of the mechanisms by which acupuncture affects the body.
Much research in the past century has strived to establish the mechanisms and
also offer proof of their action. Evidence supporting the proposed
mechanisms below may be found by clicking here.
To review studies in the clinical efficacy of acupuncture in chronic back pain,
click here.
Proposed mechanisms
Much research has been directed at discovery of acupuncture’s mechanism of
action. Attempts have been made to identify local, channel, and whole body
effects in an attempt to explain how acupuncture works to relieve pain.
The following paragraphs present the most widely accepted (and best studied)
mechanisms of action.
Local or acupoint effects
Needle insertion at acupoints is believed to stimulate A-delta or group III
small myelinated primary afferents in skin and muscle tissues.
Channel effects
Sensation at it is propagated along the channel is referred to as PSAC
(propagated sensation along channel). This sensation is believed to travel
along the small myelinated fibers at a rate of 1-10 centimeters per second in a
1-2 centimeter-wide strip. The movement of the sensation is puzzling
because it traverses the “segmental” boundaries of peripheral nerve
distribution. Research has indicated that this response results from the
contact of the A-delta fibers with inhibitory enkephalinergic cells in the
spinal grey matter.
Whole body effects
Acupuncture is believed to affect the entire body by various hormonal
mechanisms. Acupuncture is thought to initiate a generalized neurohormonal
mechanism resulting in the release of Beta-endorphins. This stimulation
also results in the release of serotonin and norepinephrine from their centers
in the central nervous system. Beta-endorphins' release is also coupled to
the release of adrenocorticotrophic hormone (ACTH), which leads to the release
of Cortisol, leading to both immune suppression and anti-inflammatory effects. A third system has been offered to explain
acupuncture’s global effects: diffuse noxious inhibitory control (DNIC).
Basically, the theory states that any noxious stimulation at heterotopic sites
inhibits pain originating in the areas of perceived pain. This hypothesis
proposes that high-intensity stimuli from both acupuncture and non-acupuncture
sites influence cells of the subnucleus reticularis dorsalis resulting in
widespread inhibition. This, coupled with stimulation of
enkephalinergic cells via the prefrontal cortex and noradrenergic stimulation
from the ascending afferents, make up the entity of DNIC.
For more information, visit these sites:
www.acupuncture.com
www.medicalacupuncture.org/
www.medical-acupunctur.co.uk/
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