Pain Science

Pain science has been around for the past 15 years and there have been huge advancements in the understanding of pain in that time period. Chronic pain is an epidemic in our country and the poor medical treatment of this condition has led many patients down the road of surgeries and narcotics without the change in symptoms. Most of the patients that we treat here at Pain Science Physical Therapy are highly active and high functioning individuals despite having high levels of constant and chronic pain. In the following section I am going to list the most common questions that patients ask and we try to answer regarding pain. This is a hand out that you can feel free to pass on to someone you know that is suffering from chronic pain.

1. What is pain?

Okay you are going to really be rolling your eyes at this one but just stay with me…we often think of pain as this awful thing we experience because of some injury to our body. But the truth is that the explanation of what pain is the first step to treating it. We have a lot of public misconceptions about pain. And those of you reading this might already be saying—“ yes I have a lot of pain but no doctor has actually found anything.” Okay so here it is—pain is a sensation that is 100% produced by your brain in response to some “perceived threat.” It is always REAL and not something we make up but it does not need to be produced in response to actual tissue damage in the body. In order to better understand this, then please read on.

2. Why do we experience pain?

Pain is our body’s alarm system. It lets us know when potential harm has happened to the body. Potential harm can be from physical/ tissue injury, chemical or temperature stimuli or even emotional stressors.

3. Do we need to experience pain?

Only if we want to survive…in other words yes. Pain is the body’s alarm system so it has to exist to help us know about “perceived threats.”

4. What is a “perceived threat”?

A “perceived threat” is the interpretation by the brain of something being possibly dangerous to the body. This is an individual interpretation and is not the same for each person. What is perceived as being threatening to one person is not threatening to someone else. For example seeing a picture of someone stepping on a nail. Most people would find this threatening but many of my patients have had this happen so it is less threatening for them. Some of my patients work on construction sites and have had this happen more than once and know that the likelihood of this happening again is high so this doesn’t concern them too much. When something is less threatening to a person it tends to cause less pain. Past experience is an important factor when we talk about pain. For example, if you have stepped on a nail and you remember it being horrible pain then just looking at a picture of this situation might be enough of a threat to actually cause you some pain in the foot.

5. Do all dangerous stimuli cause pain?

You can probably answer this question real easily by thinking about the following example, have you ever found a bruise on your body and didn’t know how you got it? Chances are that at the time of the injury your brain was so focused on something else that you didn’t experience pain. You still have tissue damage but no pain. Now let’s go to an extreme example—surfers who get their limbs bit off by sharks will often say they didn’t feel anything at all. The question is ‘why not’? The answer is the BRAIN! At the time that the injury occurred the brain is probably working really hard to help the surfer get away from the huge threat—the SHARK! If you are writhing in agony you will not be really effective at getting away from the threat, so the brain releases a lot of “danger blocking” hormones to help the surfer not feel pain and be able to surf or swim away from the shark.

6. Is there a direct relationship between tissue injury and pain?

No. We can experience lots of pain without a lot of tissue damage happening. There are lots of examples of this. If you google “nail in the brain” then you will find a picture of a guy who was having headaches and didn’t know why.   He finally went to the ER and they took a scan of his brain and found a nail was lodge there. He had been working with a nail gun a few years prior and shot himself in the head but never felt it—huge tissue damage and relatively little pain. On the flip side I know you have probably had a paper cut and it hurt a lot! Very little tissue damage but a lot of pain.

7. So the big question is—what causes chronic pain?

The answer to this is an actual physiological change to nerve sensitivity. Now all the nerves in your body have a certain threshold or sensitivity to stimuli in the environment. Nerves are your highway system constantly bringing information up to the brain from the body and back down to the body from the brain. Your nerves have to have a certain level of sensitivity to be able to detect very small changes in what is happening in the body. There are two factors that determine whether a message from the body becomes a “danger message”. One factor is how sensitive the nerve is to the stimuli. The other is the brain which we address in a bit. The first factor—nerve sensitivity – refers to low the threshold of the nerve firing actually is. All nerves have a point in which if enough information comes in they then ‘fire’ and send a message up to the brain. A great example is how much of your baby’s screaming can you take before you yourself lose your cool? For some parents you can take a lot of screaming—and the more children you have had the less sensitive you are to this over time. But if you are a new parent and you don’t understand all the different reasons your baby might be screaming, well you will be nervous and anxious and overly sensitive to your baby and probably lose your cool much earlier than a seasoned parent. A nerve behaves similarly. As the nerve gets more and more information from the body (this can be a specific stimuli such as temperature getting hotter) there is a point in which the nerve will then fire and send a ‘danger message’ up to the brain letting you know that you have put your hand on a hot stove. This is a system that fires REALLY fast in order to protect you. Well what if the nerve has become sensitive? Well then if the nerve is sensitive it will fire too quickly in response to possible or perceived threat. So now if you put your hand on a hot mug of tea it might send a danger message to your brain and you feel pain in the hand as you quickly take it off the mug. The hot from the mug is definitely not going to burn your skin unlike the hot from the stove. Yet with a nerve being sensitive it will respond the same way to 2 different stimuli –one that WON’T hurt you and one that WILL. Nerve sensitivity is a real thing. We just aren’t able to measure it in a doctor’s office or with a scan like an MRI. It is also something NORMAL that just sometimes happens to nerves and it happens to EVERYONE all over the body.

8. So if nerve hypersensitivity is something NORMAL that can happen to a nerve, why doesn’t EVERYONE have CHRONIC pain???

Well the answer to this is the BRAIN! Remember what I said early on, pain happens in the body because the brain is responding to perceived threat. So if the brain doesn’t think it is threatening then you won’t have pain…(remember the surfer and the shark bite). It is your brain that makes the decision that something bad is happening and you need to know about it. And remember that the best way for the alarm system to work is to make sure you have pain. You will quickly respond to the pain and do something different. So if it is your brain that produces pain, then we have to treat your brain to stop the pain…now here is the answer why all the TISSUE based treatment you might have been doing, hasn’t been working. In order to correctly treat pain you have to understand the cause and only by understanding the cause can we treat it appropriately. Only then can we have permanent relief of chronic pain. And in understanding pain you start to treat it.