What is pain?

The perception of pain is one of the most fundamental sensations in our body. It is the main way our body tells us that we are injured or ill. So it is not surprising that when the system of pain perception goes off track redirecting it back to normal function is very difficult.

That is exactly what happens most of the time when pain refuses to go away in spite of passage of time and numerous treatments. To understand why pain is so hard to treat one needs to understand how the perception of pain normally works in our bodies. A lot of people assume that human body works kind of like a car and doctors act like car mechanics. In other words a body part is injured which in turn leads to pain. If the doctor does a Xray or MRI scan, and finds the damage and repairs it with surgery, injection or medication. The assumption is that if the pain does not go away after treatment or if no damage is found on Xrays and other imaging tests, then the doctor did not find the correct cause of the pain and more testing is needed. The reasoning is analogous to reasoning that if a car mechanic replaced a part which he felt was faulty and the car still does not work he replaced the wrong part. Also, if the car mechanic told you that your car has no damaged parts, but it still will not run, you will expect him or her to look again as something must be damaged if the car with a full tank of gas does not start.

What most people fail to appreciate is that pain perception is actually not caused by tissue damage, but rather by electrical and chemical signals transmitted by nerves, spinal cord and the brain. Tissue damage will often turn that system on and healing of the tissues will normally turn the signal off, however in about 20% of people the system does not turn off once the tissues heal. Although there are many things we still do not understand about chronic pain, that is in essence what we think is going on most of the time when pain will not resolve.

The reverse occurs as well. People can have a very abnormal looking Xrays and MRI scans but have no pain at all, because the pain signaling pathway has turned off as it feel that the injury or changes related to wear and tear are no longer of concern. There are many studies which show that many people with “bone on bone “ arthritis and disc degeneration have no pain at all.