Acupuncture and Pain
Acupuncture originated over 3000 years ago and has been used as a way to treat many different short and long-term conditions – especially pain. Acupuncture has become increasingly more widespread and accepted as a way of complimenting other therapies and as a standalone treatment in itself.
But how does it work? To answer that question, we need to have a basic understanding of the physiological mechanism of pain before we explore how acupuncture can have an effect.
Mechanism of pain
Pain plays a vital role in the nervous system by warning the body of potential or actual injury. It is both a sensory and emotional experience. Following the introduction of a painful stimuli (for example, stubbing your toe) specialist sensory receptors called ‘nociceptors’ transform this stimuli into electrical signals, which are then conducted to the central nervous system. They are free nerve endings (Aβ, Aδ and C fibres); and they work by bringing information from the periphery of our bodies to the brain for interpretation. They are distributed throughout the skin, viscera, muscles and joints and can be stimulated by mechanical, thermal or chemical means. In addition to these, we have chemicals that act as inflammatory mediators (bradykinin, serotonin, and prostaglandins to name a few) which are released into damaged tissue to stimulate our nociceptors directly. Each of the free nerve endings possess different qualities that allow the transmission of particular types of sensory information i.e. sharp, ache, burning or throb type of pain.
Pain modulation
In 1965, scientists Melzack and Wall described what later became known as ‘the Gate Control Theory’. This postulated the inhibitory modulation of pain from a spinal cord level. But what does this mean? Well, going back to our earlier example of stubbing your toe; you will feel the touch sensation of your toe hitting the ground, carried by the large fast conducting Aβ fibres…this signal reaches your brain first. A little bit later you will feel the pain because the information related to tissue damage is carried by slower conducting Aδ and C fibres. …OUCH!
Your body also has the ability to partially block pain by releasing inhibitory chemical messengers through its descending pathways which enables the production of analgesics. This response helps to explain the wide variation in the perception of pain and everyone’s different experience; as everyone produces different levels of these analgesic chemicals.
Chronic Pain
Chronic pain is pain lasting for more than 3 months and affecting our day to day living. It is caused by alterations to nociception and may result from injury to the peripheral or central nervous systems (PNS, CNS) and may have no organic cause (structural). Although the exact mechanism of chronic pain is complicated and still unclear; it is thought that a central mechanism in the spinal cord called ‘wind up’; also referred to as hyper sensitivity or hyper excitability, may occur. This results from prolonged, painful stimulation causing an abnormal increase in the amount of pain impulses to be sent. This processing of pain within the PNS or CNS is abnormal.
The BIG Question – So how does Acupuncture change pain?
Incredibly, acupuncture has the ability to affect every major system of the body but largely has 3 main effects:
1: Reducing pain
2: Reducing inflammation
3: Restoring homeostasis (regulation of internal balance; Yin/Yang).
Ultimately, acupuncture depends on stimulation of the PNS in order to affect change within the CNS. Acupuncture promotes blood circulation and stimulates the body’s healing mechanisms by stimulating oxygenation, nutrients, hormones and analgesics such as endorphins; norepinephrine and encephalin (some of these have shown to be 10-200 times more potent than morphine!); and anti-inflammatory mediators mentioned above. Because of this release of analgesics and anti-inflammatories, it helps relax short/tight and painful muscles which further promote blood flow into these structures.
More importantly, it helps to reduce both the intensity and perception of pain in the brain by tapping into the descending pathways and aiding the modulation of the response to the pain impulses; i.e. turning down the thermostat in order to achieve muscle relaxation, range of movement, strength and ultimately movement control. People have reported other symptoms such as heightened relaxation; feelings of lightness and always sleeping well after treatment.
Article written by Shannon Marino, Physiotherapist
Re-Energise Physio, October 2016
