In simple terms pain occurs when receptors in our tissues (skin, muscles etc) are stimulated to reach a certain threshold. The stimulus can be from heat, pressure, or chemicals released when we injure ourselves or are unwell. The receptors send information to our spinal cord, and the information is then relayed to the brain. Until the information reaches the brain it is only that, information. It is not yet pain. The pain only occurs when, and if, this information reaches the brain.
Why is it that a rugby player can continue playing with a fractured wrist and very little pain, and yet an episode of sunburn can be so painful? Why is it that surfers who have lost limbs in a shark attack report being unaware of the loss at the time of the injury? It is because the brain decides how painful an experience will be. In the words of Lorimer Moseley, an expert in pain research, the brain has to decide “How dangerous is this really?” If the brain thinks the situation is not dangerous, it will dampen down or “inhibit” some of the pain information. Likewise if the brain thinks “This is really dangerous” the brain will turn up the pain response. This decision is based upon a multitude of factors such as previous experience, the environment you are in, pain beliefs, culture; the brain has to try to make sense of the information it is getting and these factors will influence what the brain decides. In the example of the shark attack, the brain is concentrating on getting out of a life threatening situation and can’t pay much attention to the tissue damage. It is important to understand that we don’t make these decisions, our brains do. These examples demonstrate that pain does not reflect how much danger you are really in, but how much the brain thinks you are in. This is an important concept in helping an understanding of pain.
In most cases pain disappears as injuries heal. However this is not always the case. For some people pain persists long after an injury has repaired, and in some cases the pain never goes away. This is because of changes in the nervous system. The nervous system is very capable of continuing to produce pain messages even though an injury no longer exists. Again, it is important to understand that this is not something we consciously decide, it is something our nervous system and brain does for us. It is easier to understand this concept if you think of phantom limb pain- the leg is gone but the pain or itch persists. Think about that the next time you ask your doctor to “chop it off”!
The good news for people with persistent pain is that as we understand more about pain and the way our brains behave the more tools we have to help. We know that having an understanding of pain is very important in managing long term pain. This article has touched on just a tiny bit of what we now know, and a fraction of what we will know in the future. I will bring you more.
Michelle Sintmaartensdyk is a Physiotherapist at the Oamaru Physiotherapy Clinic. She has post graduate qualifications in Manipulative Physiotherapy and Sports Medicine and is a Registered Physiotherapy Acupuncturist.
Pain is in the Brain.
We are all familiar with pain. Pain is normal and necessary in order to protect us from danger. Our understanding of pain has come a long way in recent years and this has led to many changes in the way health care professionals think about and manage pain. Likewise our understanding about the brain continues to grow, and without the brain, there is no pain!