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Pain and the Brain 1: Hurt doesn't always mean harm

· 4 min read

Part of the "Pain and the Brain" series

In this post, we'll explore a huge myth. This myth is about pain and it could be considered a leading cause of persistent low back pain.

Here it is - are you ready?


On so many levels this feels right to us, doesn't it? You get an injury, nerves carry pain signals to the brain and you feel pain. But the research has shown us that the experience of pain is so much more complex and nuanced than this and actually it isn't just about damage at all.

You can have an injury with no pain#

Many of us will have had experience of spotting a bruise on our arm or leg and thinking "where did that come from?". That's an obvious sign of (albeit minor) tissue damage which didn't hurt at the time of an injury. I used to see it pitch-side all the time when I was doing first aid at football games. Players would be so involved in scoring that they wouldn't notice gashes, sprains, strains, or sometimes even fractures, until they actually looked a few moments later. Or how about nosebleeds? They often don't hurt but they are caused by a ruptured blood vessel in the nose.

Moreover, if you took 100 people with no back pain and scanned them in an MRI machine, 50-80% of them would have a disc bulge and/or osteoarthritis that is producing no symptoms and absolutely no pain.

You can have pain with no injury#

Why do we describe the loss of a loved one as heartache? Isn't it because we get a tangible feeling of pain in our chest in grief? Or if you want a more medical example, how about migraines? The pain from migraines is usually very severe. But there's no damage or injury with a migraine and within a few hours the person has usually fully recovered. So what was all that pain about?

You can even have pain with no body part#

Some of you may be familiar with phantom limb pain, where a person experiences pain in a limb that isn't there. Most commonly this is due to amputation but there are actually cases of people born without limbs still experiencing sensations from a limb that never existed. Not only that, but this can be replicated in non-amputees too. In certain research conditions, a person can be made to feel pain in someone else's body or can be made to feel that kind of deep tingly sensation you get with acupuncture, when acupuncture is performed on a prosthetic limb. Even if they've never had acupuncture before.

So if you can have an injury with no pain, pain with no injury, or pain without even a body part, then our experience of pain cannot just be about tissue damage.

So what is pain really all about?#

We actually now know that many things contribute to the creation of pain, and it's all to do with complex interactions of the nervous system. But because neuroscience is complicated I like to think of it like a fire alarm. Fire alarms don't actually respond to fire, do they? Their sensors respond to heat and smoke. In the same way there are no pain signals, pain nerves or pain pathways in the body. Receptors on the nerves are sensitive to pressure or stretch, to temperature, to certain chemicals. Now, these things might imply that there was some damage in the area but actually the brain takes a lot of other things into account too. It will take information from sight and sound to work out where you are and what you're doing. It will assess your mood and the levels of any stress hormones in your blood. It will call on your memory bank to ask if you've had this pain before. And it uses your personal beliefs about your body and your health. And using all this information your brain asks one question: "Do I need to protect myself?"

If the brain feels there is credible evidence of a threat, it will create the experience of pain to protect you. Like that fire alarm sensing smoke or heat, it will sound the alarm. This in essence means that pain is not something that exists in the body, it is created by your brain and projected onto your body.

See other posts in the "Pain and the Brain" series