Part 2: What is pain, and why does it hurt?

Pain is an elaborate protective mechanism. It captures attention, and changes behaviour. And of course, it hurts. 

Here is the current, accepted definition of pain. 'An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage (IASP 1994)'. It's a mouthful. But it makes clear that pain can occur with or without tissue damage, i.e. actual or potential tissue damage. We can add to this by noting that pain has a location in the body. It hurts somewhere. And because pain is felt in the body, it is easy to blame the body part for the pain. 

So what happens when you stub your toe? Nerves in the toe send messages to your spinal cord, which relays the message to the thalamus in your brain, which distributes the information to the cortex of your brain. Lots of different brain areas then work together to determine how dangerous the message is, and whether pain would be useful. Pain is a protective mechanism. It captures attention and changes behaviour. So you look to the toe and make sure it is alright. You rub the toe and give it extra care. And you hobble for a few minutes until you are sure it is safe. Because it hurt, you avoid stubbing your toe in the future. That's why pain hurts. To stop you doing the thing in the future.

But what if it hurts for months, or even years? The protective quality of pain is no longer useful. Instead of helping you to avoid genuine danger, the brain has become overprotective and generates pain during safe activities. You might avoid bending forward, or turning your neck a certain way. Maybe you begin to use one leg more than the other. In any case, avoidance no longer helps the pain. 

In the next few posts we will explore the best ways to improve long-term pain. The first step is to learn about pain, so if you are reading this post then you have already begun.

DAVID MOEN