The vast majority of my patients, if not all of them, come to see me because they are experiencing some sort of pain or discomfort.
This often annoying, sometimes debilitating, but definitely necessary sensation exists to protect us from a treacherous environment which hurls bodily harm our way on a daily basis. The problem with pain lies not in that it exists; it is more so that pain seems to be poorly understood.
In an effort to help you understand pain a little better, I will attempt to describe how it works (to the best of our current knowledge), and what sorts of things can influence it as well.
The topic of pain/pain science is–to put it bluntly– very complex, and a short article like the ones I write will not fully do it justice. If you would like to learn more about the subject, I would highly recommend you read Explain Pain by David Butler and Lorimer Mosley.
Let’s start first with how pain works using the example of getting bit by a puppy. The events follow as such:
- A puppy bites your finger with its needle-sharp teeth, because that’s what puppies do.
- A special sensory nerve in your finger called a nociceptor is activated because the pressure from the bite can possibly cause damage to the skin and underlying tissues.
- The larger nerve that the nociceptor is associated with takes the message that there is possible damage and relays it to the brain via your spinal cord.
- The signal arrives in an area of your brain called the thalamus, which acts like a police officer telling cars where to go when the traffic light isn’t working.
- The thalamus sends the signal to our lymbic system (which controls emotion and memory), our somatosensory and motor cortex (which allows us to feel things, and move our body), and to the frontal cortex (which allows us to think at a higher level about what just happened).
- You say ouch, and pull your finger away from the offending canine’s mouth.
Well, almost. You see, all of the stuff I described above happens extremely quickly–in a matter of milliseconds really–but a lot of stuff goes on behind the scenes which can influence how much pain the person who is bit will experience.
Has the person who got bit already have a fresh bite in the same area? Is there an old injury to that finger from their past? Are they afraid of dogs from a negative encounter in their past? Is the dog on a leash or in a fenced yard, or did it come up out of nowhere? Were you expecting the bite? How much do you know about dogs and their bites? Do I need that finger to make a living?
Each one of these questions has a physical or emotional component to them which can greatly effect the amount of pain that would be experienced by the individual who was bitten. The interesting thing to note is that the processing that takes place that determines how much pain is experienced in this situation happens almost entirely in the brain!
The nociceptors at the site of the bite are very specialized nerve cells which respond to damaging or potentially damaging stimuli. They are considered “high-threshold” sensors that are only activated when any stimulus near them threatens the tissues in the surrounding area. They respond to high level heat or cold, pressure, and chemical stimulants, but not in the way that you would think.
As far as we can tell, there is not a 1:1 relationship between how many of these nerves are activated–or to the degree in which they are activated–and the amount of tissue damage that is observable, or the amount of pain which a person will experience from an injury or potential injury.
You’ve probably noticed by now that I have been saying “potentially” as a qualifier quite a bit, and that’s because it is important to note that just because we feel what we know as pain, doesn’t necessarily indicate that there is in fact any damage that we can point to through imaging or otherwise.
In fact, studies on low back x-rays and MRIs have shown that the ability to predict the symptoms a person may be experience based upon looking at imaging alone is quite unreliable–particularly in chronic pain cases.
The bottom line is that pain is very strange, not at all as black and white as we might like to think. There are no nerves which send “pain” signals as we know it. Our nociceptors can be thought of more as “danger” nerves; a warning system. The system can go haywire sometimes and send signals when there is no threat, get mixed up with other signals and get interpreted as pain, or send more signals than it ought to.
When we experience pain, we should take pause, and try to find out what that signal is trying to tell us. Is that chronic low back pain really related to the disc herniation I had 15 years ago, or did that experience change how I experience regular nociceptive input which is trying to tell me that I need to move more, or change positions to avoid damaging my nerves, muscles, or joints? Current thinking seems to point to the latter.
Again, this topic is much more complex than a ~1000 word essay can sum up. All I ask is that if you suffer from chronic, or recurrent pain in particular, that you try to be open to this line of thinking. The next time you have a flare up, go over the questions I posed about the dog bite, and consider how those types of things may be influencing your pain, and if your doctor ever says that your pain is “all in your head”– Ask them what they mean by that.