Sunday 5 August 2012

The No.1 Myth about Pain is exploded with 5 Simple Facts

What do we think we know about pain?


The traditional theory of pain suggests that an isolated pain system carries messages from pain receptors in the skin to a pain centre in the brain. This is called the Specificity theory and it is commonly taught as fact, rather than theory.

Contrary to popular belief, the connection between a damaged organ and pain is not straight forward and direct.

Consider the highly variable link between injury and pain: injury may occur without pain, and pain may occur without injury. - Click to Tweet

"We are learning to accept that pain is not produced by the simple activation of a single, specific, isolated signalling system but is subject to a series of controls acting in the context of a whole integrated nervous system." (The Challenge of Pain p.295)

Examples of the Variable Link between Pain and Injury:


1. Injury without Pain (Congenital Analgesia)


Some people are born without the ability to feel pain.

Without pain acting as a warning and a teacher the following situations can occur:
  • Biting into tounge while eating.
  • Failing to feel pain when walking on a leg with a cracked bone would cause you to walk on it until it broke completely.
  • Failing to feel discomfort when remaining in one position too long would mean that you don't shift your weight and sustain damage to your joints and ligaments.
The fact damage can sometimes be present, without pain being experienced, shows that pain is not a simple signalling system with a direct and straight-forward relationship with a site of disease/damage.

2. A Delayed Response to Pain (Episodic Analgesia)


When injured, it is quite common to feel no pain until hours afterwards.

It doesn't seem to make a difference if the injury is minor or severe, a graze, or a severed limb. And it's not that pain is noticed and then brought under control. There is simply no pain.

Many of us have accepted the delayed pain response as a common phenomena, allowing us to accept that pain is a complicated thing.

It starts to become clear that there are a number of complicated processes that determine the intensity and duration of pain - factors which bear little relation to the scale of ones physical injury.

Newer theories of pain such as The Gate Theory look at what activities of the nervous system intervene between injury and pain perception and start making sense of why the relationship between injury and pain is so variable.

3. Pain without Injury


There are some pains that do not appear to result from a direct relationship with injury or damage.

For example:
  • Tension headache and migraine are two examples where the origin and cause of pain is not known or understood.
  • Trigeminal Neuralgia - where a light touch to a trigger point provokes an agonising stab of pain.
  • Crippling lower back pain where diagnostic techniques can find no damage.

All of these pains are likely to result from a "failure in the function of central control mechanisms." (The Challenge of Pain, p.9) see also What are Functional symptoms?

Traditionally these pains are a source of great frustration, but as pain begins to be recognised not as a symptom of damage but a problem in it's own right, these pains prompt a greater understanding of the nature of pain.

4. Disproportionate Pain


It is commonly assumed that pain is a simple mechanism to communicate a warning, but in many cases the pain response is not proportionate to the problem; the problem being far more severe or far more trivial than the pain it provokes.

For example:
  • Passing a kidney stone is famous for being excruciatingly painful, but from a mechanical point of view, passing a kidney stone is a trivial event.
  • There are also relatively small number of nerve impulses sent to the spinal cord when a kidney stone passes through the ureter - despite this, the effect in pain is gigantic.

Clearly, severe pain does not automatically indicate the body is severely damaged.

5. Persistent Chronic Pain long after the injury is healed


Persistent pain can be experienced year in year out long after an injury has healed.

Examples include:
  • Phantom limb pain "where the limb is incapable of producing pain, yet pain is constantly felt, though no injury is occurring." (The Challenge of Pain, p.10)
  • Peripheral nerve damage that produces excruciating burning, shooting, stabbing pains that may occur spontaneously long after the tissues have healed.
  • Minor commonplace injuries can also provoke the onset of severe pain that can persist for years; pain that may take the form of spontaneous attacks not dissimilar to those described above.

This is in direct contrast to pains which prevent an injury or enforce inactivity and rest. In these cases the pain serves no biological purpose.

"Chronic pain can even be detrimental to the survival of man. The pain can be so terrible, so feared, that people would sooner die than continue living with it."  (The Challenge of Pain, p.12)

It is not helped, that while the traditional understanding of isolated, direct, and easy-to-understand pain persists, support and understanding for chronic pain suffers is limited.

"Acute pain which is the basis of the traditional training of physicians is wonderfully controlled by our modern day drugs. Chronic pain, however, requires a new set or rules, and we are still novices in these new approaches to pain." (The Challenge of Pain, p.273)

Happily, examples 1 - 5 above contain clues for the control of pain in all it's shapes and sizes, and pain is no longer considered a symptom, but a syndrome in it's own right. - Click to Tweet

Sadly, for those with pains we don't understand, or for which we have no adequate treatment, new solutions for pain relief can't come soon enough.