What is pain?

Some sort of pain is arguably the most common reason to go see a doctor. When one looks into the most common "chief complaints" (the primary reason a patient seeks medical attention), most of them have something to do with an ache or pain. But what exactly does it mean to hurt? What is pain?

I have medical residents from a variety of fields rotate through my office (I am a pain management physician). When giving my introductory lecture, one of the first questions I ask them is, "What is pain?" Every single one of them has trouble with a formal definition. To be fair, after 4 years of medical school and 4 years of an anesthesia medical residency, I was similarly unaware of a formal definition until my pain medicine fellowship. I thought that hurting should be self explanatory. However, pain has a formal definition. Once one understands how it is defined, one is better able to begin to understand the nuances of what it means when someone says he or she is hurting.

Defined by the International Association for the Study of Pain (IASP), pain is "An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage."

In my experience as both a pain medicine physician and patient with a chronic pain syndrome, I think a thorough understanding of this definition is vital for both doctors and patients alike. There are a few things to note. First, pain is a deeply personal experience. Pain is processed in the brain, an organ which still holds vast mystery. People come from drastically different cultures and backgrounds, and therefore no one can truly know what anyone else is feeling. If someone is reporting pain, then by definition the pain is real as that is their experience. The fact that there may be no immediate tissue damage visible on a scan or identifiable on a test does not disqualify the patient's experience. The only exception, and the only reason to not believe someone reporting pain, would be in the scenario of malingering, where an individual truly lies or invents a symptom for so called "secondary gain," like getting out of work or a financial award from an accident. In my experience, malingering individuals are very few and far between.

Second, pain is emotional. It is more than simply irritated tissue sending a message along a nervous system pathway to the brain, which perceives an "ouch." Pain, particularly when chronic, is suffering. Third, potential tissue damage can be a cause of pain. Modern medicine does not have all of the answers. For example, to my knowledge, the scientific community still has not found anything abnormal in terms of the muscle tissue itself in patients with fibromyalgia. However, we know that using functional MRI (essentially a way of measuring brain activity), people with fibromyalgia respond differently to exposure to both painful and non painful stimulation. Therefore, it can be very reasonably concluded that there is pathology involved in patients with fibromyalgia. Modern medicine simply lacks a good explanation for it. Just because we lack a full understanding by no means minimizes an individual's experience.

I hope that this post helps explain what pain is. It is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Sometimes the reason is obvious, sometimes not. The lack of easily identifiable tissue damage is by no means a reason to dismiss an individual's experience. Unfortunately, there are not a lot of easy answers to a lot of pain syndromes. In a good number of patients, a specific diagnosis cannot be found. I say "I don't know" to the question "Why?" a lot more than I would like. In my next post, I will discuss the continued importance of defining terms as we continue A Walk Through Pain.