What is Pain?

September 17, 2015

shutterstock_77744515“Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” This is the definition of pain provided by the International Association for the Study of Pain, a nongovernmental organization founded in 1973 and now active in 133 countries. The American Nurses Association endorses a different definition, first proposed in 1968. This definition is: pain is “whatever the experiencing person says it is, existing whenever the experiencing person says it does.”1

From the standpoint of empathy, that latter definition seems pretty good. Whichever definition we choose to use, though, one thing is completely clear: 50 million American adults of Americans say they live with chronic or severe pain.2

So how does pain work?

The Basics of a Pain Response

Some pain, of course, is related to specific diseases, injuries, and disorders, and is treated accordingly. For instance, a burn wound may be treated with topical anesthetics or analgesics to relieve the victim’s suffering. Drugs and treatments are developed for, let’s say, the pain associated with diabetic neuropathy.

But some research is actually focused on understanding how we come to experience pain in the first place, and what we can do about it. Neurologists, chemists, and others are very involved in studying what happens to the brain during pain. When brain tissue becomes inflamed, for example, is that a cause of pain, a response to pain, or both?

To briefly synopsize what we know about the very basics of how we come to experience pain: when certain stimuli occur, an electrical signal is sent via neurons from the injury site to a site in the spinal cord called the “dorsal horn.” This region processes the pain, like a radio receiving signals over the airwaves. In the processing, this region seems to decide to some extent how severe the pain should be. That is, some “dampening” of pain may occur here before the dorsal horn then sends the brain a message – or causes a “kneejerk” type reaction in the pained area, presumably an evolved response meant to keep us safe.3

The Light Side of Pain

To put the above into concrete terms: say you fix a bath. You stick your toe in the water to find out if the water is too hot or too cold. If the water is scalding, a nerve in your toe sends its information to the dorsal horn, which immediately causes a reaction to make you withdraw your foot, while it also sends information to your brain. Quickly processing the information, your brain seems to produce a thought that goes something like this, “That water is too hot. Wait.”

And voila! Your pain has saved you!

The Dark Side of Pain

 In the above example, pain plays a very important role in protecting you. In fact, when you stuck your toe in the water, you invited pain in the knowledge that if you felt it, you would be able to avoid greater pain. Indeed, much of the research that goes into pain takes the central idea that much pain is beneficial and protective. And certainly the absence of pain—numbness, for example—can be disastrous – it can lead you to great injury.

But what about pain that seemingly serves no purpose at all? Like migraines. Or fibromyalgia. Or pain associated with chemotherapy. Unlike, say, diabetes, which has measurable symptoms that help explain the pain, the symptoms of many problems—including migraines and fibromyalgia—is the pain itself.

A Migraine Connection

One aim of medical science is to counteract pain that causes people unnecessary, unproductive suffering. No one has found a productive or a preventive reason for the existence of a migraine, for example. Actually, the opposite seems true: migraine and other seemingly un-productive pains actually cause more pain, because they limit the ability of people to exercise, to enjoy their lives, to stimulate their minds, etc.

So what is migraine pain all about? As of now, only theories exist. But that shouldn’t stop us from trying to limit the pain as much as possible. And finding ways to limit pain actually may end up revealing the source of the pain itself. Like reverse-engineering, perhaps when we find how to alleviate the pain of a migraine, we will discover what causes—not just what “triggers”—the migraine. This is part of the work being done by physicians at Migraine Treatment Centers of America and others.

The Omega Procedure, for example, combines two types of neurostimulation techniques that have proven very successful in alleviating the pain of a migraine, though it does not stop a migraine from forming. Put simply, when a migraine sufferer feels the beginnings of a migraine, she can flip a switch on a remote control that sends a soothing signal to the area of the head that seems most affected by migraines. When these signals are delivered, they have proven very good at blocking the development of the full migraine pain.

On one hand, does it matter how it works if at least it works and causes no harm? As it relates to your next migraine, of course it doesn’t matter. But if we learn exactly why it works, might we able to learn how to prevent a migraine in the first place? We might, we might indeed. And that would be a great thing.


  1. Bernhofer W. Ethics: Ethics and Pain Management in Hospitalized Patients. The Online Journal of Issues in Nursing. October 25, 2011: Vol. 17 No. 1.
  1. News Medical. New NIH study shows nearly 50 million U.S. adult experience chronic pain or severe pain. August 20, 2015. http://www.news-medical.net/news/20150820/New-NIH-study-shows-nearly-50-million-US-adults-experience-chronic-pain-or-severe-pain.aspx
  1. National Institute of Neurological Disorders and Stroke. Pain: hope through research. Accessed on September 13, 2015. http://www.ninds.nih.gov/disorders/chronic_pain/detail_chronic_pain.htm

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