Let Me Explain Pain

If you have been in pain for a long time, you may well have tried many different treatments from acupuncture to osteopathy, steroid injections to Bowen technique. If you are still in pain then presumably none of these therapies “did the trick” and you are still searching for an effective treatment. In fact it may be that the reason that none of those treatments worked was that none of the therapists took the time to explain why you are in pain and how pain works.

As an osteopath, pain is my currency. I get patients to measure it from 0 to 10, and to describe it: aching, sharp, stabbing, etc. But it is far more complex than most of us could ever have imagined. And the art of getting to grips with a patient’s pain is to “Explain Pain.” This is a relatively new approach to working with chronic pain and is the brainchild of two Australian neuroscientists, David Butler and Lorimer Moseley, the founders of the Neuro-Orthopaedic Institute or NOI. What follows is largely based on research and concepts laid out in their excellent book, Explain Pain, which they wrote for patients.

What is pain for and why is it not always a good measure of what’s wrong?

danger - pixabayPain is an alarm system – it exists to let you know that there is something wrong. You would therefore be forgiven for assuming that the more severe the pain, the  greater the danger. However there isn’t always such a simple correspondence between the severity of the injury and the severity of the pain. In fact it is the brain which decides whether something hurts or not – 100% of the time. And the brain takes account of considerably more than the severity of the injury.

In “deciding” how much pain is appropriate, the brain relies on context: memory, reasoning and emotion.  First off, the brain must decide whether pain is the best course of action. For instance in  the phenomenon of battlefield anaesthesia, a soldier may have lost all or part of a limb, but will not experience pain until he is out of danger from the enemy as escape from the battlefield is the highest priority at this point.

There are other less serious examples:

  • A cut or pin-prick to a violinist’s left finger will hurt considerably more than the same cut to a dancer’s finger or even to the violinist’s right finger – as it is the left hand which does the fingering.
  • I remember as a child, being convinced that my mother had filled the bathroom sink with very hot water, and when she made me put my hands into the water to wash them, my brain/body reacted to the imagined heat with pain even though it had been the cold tap she had turned on!
  • In his book, Painful Yarns, Lorimer Moseley recounts an incident when he was out walking and felt a scratching sensation just above his left ankle. Assuming the scratch came from a grass stalk, he flicked his ankle, and carried on walking, without feeling any pain – because the brain did not perceive any danger. However it turned out that the scratch was actually a snake bite, and Moseley was lucky to survive as this was an Eastern Brown, which has a lethal venom. About six months later, Moseley was out walking again and experienced a prickling sensation on his left leg. The pain was immediate and intense and shot up his leg “like an electric bolt”. He doubled up and fell over, immediately mobilising his friends to take action and call for an ambulance – assuming of course that Moseley had been bitten by a snake again. However when they stopped to examine his leg they realised that it had just been scratched by a twig! But the pain did not end here. Even knowing that he had not been bitten by a snake, Moseley experienced groin pain on and off for a week. As he says “It was as though my brain, at a deeper implicit level, wasn’t convinced that I was completely safe from harm.”

Explain Pain details other pain phenomena which are even stranger, including phantom limb pain (pain experienced as if it emanates from a limb which has been amputated), couvade, in which men experience the pains of childbirth when their wives are in labour, and the fact that the effectiveness of aspirin depends on its shape and colour.

Butler and Moseley identify four types of “ignition cues” for pain:

  • emotional state: distress lowers the threshold for pain, and a stressful situation such as being bullied at work may lead to tissue changes (eg tension in shoulder muscles) which may also contribute to pain levels
  • the perceived cause of the pain: in women post-mastectomy, breast pain which is perceived as returning cancer is more intense than it is if the pain is perceived as being due to another cause
  • knowledge and understanding: the less knowledge you have about a medical procedure, the more pain you will experience during the procedure and afterwards
  • action: I know from my own clinical experience that pain often diminishes once the patient has made an appointment to come and see me. The brain stops the pain because you have acted on it, because it knows that you have listened to the alarm signal.

How does pain work and how does it get modified by the brain?

There are good physiological reasons for how pain perception gets modified by these ignition factors. If you would like to know, read on. Otherwise you can skip the next few paragraphs and go straight to What is to be done?

Neurology: pain messages start with nociceptors. These are neurones (nerve cells) with sensors for temperature, pressure and chemicals). If enough sensors are activated, the neurone will fire, sending an electrical impulse which travels up its length to its terminus in the spine at something called the dorsal horn. Here it synapses (connects) with a 2nd order neurone which relays the information to the brain. However there are other neurones getting involved in the dorsal horn. These include inhibitory neurones coming down from the brain, which dampen the pain signal, but also neurones coming from brain which enhance the signal and make it stronger.

Strengthening of the signal in the 2nd order neurone occurs by a process of sensitisation at the dorsal horn. This can lead to hyperalgesia (where a mild pain is felt as being much stronger), and allodynia (where even a light touch can seem painful). This increase in sensitivity of the 2nd order neurone is actually due to changes which occur at the synapse as more neurotransmitter is released and in the neurone itself, which may actually grow more sensors. So we could say that the volume gets turned up on the second order neurone, so that it appears that things are worse than they really are, and this is what often happens in chronic or persistent pain.

Sensory Homunculus - wikipediaUnfortunately similar things happen in the brain. The part of the brain which is responsible for sensation (including pain) is known as the sensory cortex and it is divided into areas corresponding to different body parts – there are larger areas in the cortex corresponding to body parts which have high sensitivity such as hands and tongue than those which correspond to parts like the feet which have low sensitivity. In chronic pain, changes take place in the sensory cortex leading to increased sensitivity and widening of the painful area.

Very often by the time pain becomes chronic, the tissues that were injured will have healed. So there may be no good reason to be in pain. It is the hypersensitivity of the brain and nervous system that maintains the pain beyond the point where it is related to actual tissue damage.

Persistent pain also results in changes in many other systems which would normally be associated with a state of high alert:

  • the endocrine (hormonal) system, including adrenal glands which are contributors to the fight or flight response
  • the sympathetic nervous system, which keeps you ready for fight or flight and leads to increases in heart rate, respiration and sweating and alertness
  • the motor system, for instance the hamstrings will be “on” permanently and ready for flight
  • the immune system: a recent study (using rats) found that chronic pain led to genetic changes in certain types of immune cells¹

Unfortunately all of these may in turn contribute to increases in pain. For instance adrenaline released as part of the fight/flight response can contribute to pain levels by increasing sensitivity in the dorsal horn.

What is to be done?

So if chronic pain is so much a product of sensitisation in the brain and spinal cord, what can an osteopath do to help? To some extent there is always work to be done on the tissues. Even though the original injury may have healed, there will still be some tissue changes which need addressing particularly if the patient has developed compensatory patterns.

Secondly patients recover better if they understand pain mechanisms and can be encouraged to fear pain less and do more. So part of my role as an osteopath is to help my patients understand better what is going on when they experience chronic pain and to encourage them to be less fearful and to try doing some of the things they have stopped doing because of their fear of pain. A gradual increase in gentle activities can bring about changes in both the brain and the body which reduce the sensitivity of the dorsal horn and thus lead to reductions in pain levels.

There are also specific strategies which will help to get pain under control and turn the volume down on it:

  • meditation and relaxation
  • pacing of activities if the patient is in a boom and bust cycle
  • social contact

These are all things the osteopath can encourage – and it is all about enabling the patient to take control.

And the relationship between therapist and patient is also important. So if you like and trust your therapist (be they an osteopath, chiropractor or massage therapist) and they can “explain pain” to you then half the work of treatment is done.

Remember knowledge is power – and pain relief!!

1. Cynthia Lee, McGill University. Chronic pain changes our immune systems: https://bit.ly/23xR9q9

Sorrel Pindar, Registered Osteopath and clinic director

Categories: Back health, chronic pain, Dorsal root ganglion, Explain Pain, Health and Wellbeing, neck and shoulder pain, Osteopathy, Pain mechanisms and shoulder injuries.

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