How does acupuncture work to relieve pain?
Firstly we need to understand the basic mechanism and physiology of pain in relation to injuries.
Most people assume that if you have pain, there must be a structural reason for it. In other words, there must be some form of structure (bone, soft tissue, or disc) actually pushing on the sensory nerve, causing it to continuously fire and send signals perceived as pain. This assumption is not always true. It has been suggested that in over 90% of chronic pain cases, particularly chronic lower back pain, there is no major structural reason for the pain – no bulging disc, nothing pushing on a nerve – but the person still feels pain!
Why is the pain still there?
The body is actually caught in a sensory motor loop, meaning that it has forgotten how to shut the pain signal off. This is due to a neuropathic problem where the nerve itself is swollen, firing continuously and sending incorrect information to the brain; hence creating a major problem as the body is stuck in a pain cycle.
The second problem involves an evolutionary survival mechanism of our brains. Let’s take knee injury as an example. If you bang your knee into something, your brain immediately takes measures to protect it. The brain doesn’t know what happened to the knee, but it assumes a worst-case scenario in which you are losing lots of blood and the injury is perceived as life threatening.
The brain sends a message to restrict the blood supply going into the knee and the blood return leaving the knee. This phenomenon is known as “guarding”, and is actually a smart choice – if a poisonous snake bit you, slowing blood flow to the area lessens the chance of the poison spreading; or if you were badly wounded, reducing blood flow makes you less likely to bleed to death. The downside to guarding is that cutting off blood flow to the knee – while lifesaving in times past –makes it stiff and weak, and dramatically limits the knee’s ability to heal.
So how does acupuncture help?
Acupuncture points are areas within the tissue with greater concentration of sensory fibres, capillaries, lymphatic vessels and mast cells. Gentle needle penetration into these neurovascular nodes causes complex electrical and chemical messages to be conducted through the body via the nervous system, endocrine, lymphatic and immune systems. In clinic we like to refer to acupuncture points as reactionary points, as needling these points creates a reaction in the body.
It is believed that inserting acupuncture needles into the skin at these peripheral sites “jumps” the neural threshold on the position nerve (nerves that register the position of pain) pathway, so that the signal can reach the brain. Once the brain registers the location of the pain, it releases enkephalins – natural pain-relieving substances that plug up pain receptor sites in the brain, spine, and local tissue, stopping the pain.
Most pain relief from acupuncture is very fast.But some time after needling the pain will return, as the “bad habit” of the nerve chronically firing below threshold re-establishes itself. But if the patient returns within a few days to get another treatment, the neural threshold will be jumped again. Keep jumping the neural threshold, and eventually the central and peripheral nervous systems realise that it’s better to operate in the non-pain state than in the pain state and the “bad habit” is broken. The technical term for the body returning to its pain-free balance is re-establishment of neurological homeostasis.
Once this happens, the brain is no longer receiving pain signals from the knee, and no longer thinks the knee is injured or threatening the survival of the body. Instead of guarding and restricting blood flow to the area the brain now does the opposite, increasing blood flow to begin the healing process.