As a chiropractor, it is not uncommon for people to come to my office in pain. We are a profession that has become well known for our non-surgical treatment of back and neck pain, and with good reason- chiropractic works marvelously for such problems. My mom has experienced this at least three different times when I’ve gotten rid of migraines on the spot with a cervical adjustment. But what about the cases that don’t respond quite so quickly? What about chronic pain?
First, let’s cover the basics of pain.
1. Pain is all in your head. Really.
Pain is not a sensory event, but a conscious one. There are receptors throughout the body that detect light, taste, smell, vibration, temperature, blood pressure, mechanical stress, muscle stretch, and tissue damage (nociception), but none actually sense pain. The nerves in our body can sense tissue damage and relay the information to our brain, but our perception and reaction to that information is what we have come to know as pain.
The easiest way to explain this concept is to use examples of pain and nociception that are independent of one another. A classic example of pain without nociception is phantom limb pain. We can’t blame this type of pain on tissue damage since the nerves that would normally sense that tissue damage were removed along with the limb! Phantom pain is thought to be “learned pain”- a concept we will revisit later. Another example is pain that starts after a stroke. The body part that is perceived as being painful was never injured, but the neurons that represent that body part were damaged, resulting in the experience of pain. The key here is that the presence of pain does not necessarily indicate that the painful tissue is actually damaged- it simply means that the neurons in the brain that perceive/create the conscious event that we call pain have come to threshold. That doesn’t make the pain any less real, but is a concept that will be important in a later blog post.
An example of nociception without (or with minimal) pain is when an athlete gets injured on the field but continues to play despite obvious injury. Other stimuli at that time (endorphins, distractions from the other team, teammates, coaches, and the roaring crowd, preconceived ideas of how much the injury should hurt) affected how the brain dealt with the nociceptive information it was receiving, and changed the pain it ultimately felt. This leads me to my next point…
2. A LOT of different things affect our perception of pain.
Pain is a lot more complex than we often give it credit for, undoubtedly because of how many different areas of the nervous system are involved. There are many, many levels of the nervous system where pain signals can start or the signals can become scrambled. Take the above scenario as an example. An athlete may not recognize the extent of the tissue damage and feel as much pain as we would expect for a number of reasons. The endorphins that bathe the athlete’s nervous system during the game work on the brain stem in much the same way as morphine. An area of the brain stem called the periaqueductal gray then sends signals down to the spinal cord to inhibit nociceptive neurons. The sheer act of moving, which stimulates sensory nerves called mechanoreceptors, also inhibits nociceptive neurons in the spinal cord. Distractions from the crowd and teammates affect the frontal lobe’s ability to focus enough to generate the perception of pain. The athlete’s state of mind and mood affect the limbic system- the part of the brain that generates the emotional side of the pain experience. There are surely a multitude of other things that can influence such a scenario, but by now you get the idea.
3. There are two different types of pain- acute and chronic.
The mechanism behind acute pain is what people usually think causes all pain: tissue damage. Bodily damage can be caused by a number of things; a cut or a bruise, an invasive tumor, muscle soreness from a hard work out, sprain or strain, a burn, gangrene, or other physical injury. And while pain is never a pleasant experience, acute pain is incredibly useful- it serves as a warning. Without pain we wouldn’t know when we are damaging our bodies and would surely wear them out very quickly. People with congenital insensitivity to pain typically lead short, injury-ridden lives for this reason. We need acute pain. It teaches us valuable lessons.
Generally, pain is said to be chronic when it has persisted for at least three months. Most often the initiating event is acute (injury), but the fact that the pain lingers for so long makes chronic pain completely different in it’s pathology and therefore, treatment approach. Often chronic pain persists long after the tissues have healed and the body has otherwise recovered. This indicates that there is some level of neurological involvement- whether it be at the level of the brain, brianstem, spinal cord, peripheral nerves, or somewhere in between. Now, that’s not to say that some cases of chronic pain are not directly due to downstream peripheral effects of old injuries. Perhaps an old ankle sprain just never really healed properly- the ligaments are now unstable or the muscle firing pattern has been altered. However, I would be one to argue that even in those cases there is some degree of neurological involvement that should not be (but often is) ignored. Sure, altered biomechanics sounds like a purely musculoskeletal problem, but the brain, cerebellum, and brain stem are always well aware and in control of everything that goes on in the body including what your muscles and tendons do.
4. There is no way to accurately measure pain.
Sure, we like to give the illusion that we can measure pain, but because pain is incredibly subjective it is also incredibly hard to quantify. In medical offices we like to use the visual analog (0-10) scale (VAS) which is an alright means of assessing someone’s pain, but I think it’s much more useful for tracking individual progress than anything else. As much as I may try, I have no way of knowing what a 9/10 pain feels like to you. I can, however, safely assume that I’ve made a pretty profound change in your symptoms if I figure out a way to bring that 9/10 down to a 3/10. The VAS is a game of comparing apples and oranges. If you compare apples to apples and oranges to oranges it has it’s uses, but it still doesn’t come close to telling you what the other person is going through.
5. Medications and Surgery don’t fix the underlying problem*
Not only do medications not fix the problem, many of them do more harm than good. Morphine, hydrocodone, tramadol, vicodin and codeine are all opioids and work much like heroin or endorphins in the brain and brain stem. They work largely in the brain stem, firing pathways like the ones discussed before that inhibit nociceptive neurons. The problem is that while they are effective at getting rid of pain in the short term (or at least making you so sleepy you don’t remember you have pain), they do nothing for the long term health of the brain- actually, quite the opposite! All of these drugs are highly addictive and often require more and more of the medication to produce the same effect because the body builds up a tolerance to them over time. Meanwhile, these drugs do nothing to improve the overall health of the brain, nor do they encourage the brain to relearn how to inhibit those pain pathways on it’s own. The other major class of pain medications is COX inhibitor drugs such as celebrex and aspirin, which decrease inflammation. There is certainly theraputic value in decreasing inflammation, but there are many other ways to decrease inflammation in the body without drugs.
Surgery for chronic pain often involves cutting nerves that go to the painful body part. The problems with this approach are numerous, but the most important is that it’s often not the body part causing the pain in chronic pain conditions- it’s the brain and brain stem. Not only that, but such surgery usually has to be repeated every few months because the nerves grow back! And we wonder why healthcare is so expensive?
*This statement, as with most things in healthcare, is not absolute. If pain is caused by tissue damage- a broken bone, meniscus tear, tumor, etc then surgery will most likely fix the problem. In this case, I am referring to chronic pain, which is more often neurological in nature.
Want to learn more about pain? Check out these videos:
Understand pain in less than 5 minutes
An excellent lecture about pain
A pretty good Ted Talk about pain (although I have a different treatment approach than he does)