Pain is a normal, but unpleasant, experience you feel in response to what your brain believes to be a threatening situation and can involve actual or potential tissue damage (Butler & Moseley, 2003). The pain experience is what motivates you to take notice of tissue damage and do something about it. When you accidentally step on a sharp object your brain alerts you to the threat (tissue damage) and you will quickly remove your foot from the object to prevent further damage. Think of your pain as an alarm system; it has the capability of sending danger messages to your brain when your brain perceives that it is under threat. Your brain then processes these danger messages and decides what the necessary action your body should take to prevent further tissue damage (like removing your foot from that sharp object). This system is essential to your survival.
We already know that pain can be related to a change in your tissues. Postural pains, pains from a sprained ankle, and pain from a bulging disc are all the result of some degree of damage to the surrounding tissues. You would assume that the larger the degree of tissue damage, the greater degree of pain. So, why is a paper cut on a finger so painful? Why are migraines so debilitating?
What we now understand is that the severity of the pain report does not always give an accurate indication of the degree of tissue damage. Paper cuts on a finger typically involve only a minor amount of tissue damage (which heals with little or no care on your part), but the degree of your pain report is usually quite high, while some life threatening cancers can go undetected for years as there are no associated symptoms. This highlights our understanding that pain is a much more complex phenomenon than we expected.