Some Thoughts on Pain

Have you ever noticed that when you are in pain you want to swear more?  Researchers have looked into this and found that swearing may actually have an analgesic effect.  They speculate that the brain circuitry linked to emotions might be involved; they found that when we swear we activate an ancient and primitive part of the brain, the ‘amygdala’ (an almond-shaped group of neurons that can trigger a fight-or-flight response in which our heart rate climbs, making us less sensitive to pain).  Normal speech doesn’t trigger any activity in this area but thoughts, memories and emotions may do.

I have recently been doing quite a lot of thinking and reading about pain, triggered by a recent course that I attended at York University.  The course was called “Explain Pain” and was delivered by David Butler who is a bit of a rock star in the field of pain science (I post the occasional YouTube clip of him on the CCC Facebook page).  The course was hard work; pain is hard work!

What is pain?

There are a lot of different definitions of pain, most of which involve a fairly in-depth understanding of neuroscience so I’ll spare you too much detail.  Basically, pain is part of our brain’s way of ensuring that our bodies don’t do something damaging.  Pain is a very sensible approach for your brain to take: if, for example, you have just fallen on an outstretched hand and broken your wrist, it will stop you from causing any further damage to that wrist and give it a chance to heal.  In fact, pain is essential to our survival as a species as it causes us to stop and pay attention to an injury and take action to help ourselves get better.

Unfortunately, pain is not so helpful when your injury is 10 weeks old and finished healing a good 2-3 weeks ago, when there is no longer an injury or any danger in moving that wrist.  This sort of pain is often referred to as chronic pain (chronic just means that it has been there for longer than the normal healing process should usually take – most people heal from even a broken bone within 8 weeks).  Chronic pain is often the result of unhelpful beliefs or poor understanding about injury and healing or fear of re-injury.  Where chronic pain is concerned, knowledge is power!

What is surprising to a lot of people is the fact that there is no ‘pain centre’ in the brain; no single point that lights up on an FMRI machine when someone experiences pain.  There are no pain pathways either – instead, sensory neurons spend their time “sniffing” their environment and then reporting their findings back to the brain.  How the brain determines your response to the information given to it by its neurons depends on many factors – it draws from the current environment as well as from you past experience, knowledge and beliefs.

Let’s take an example to try to help illustrate this – when you think of someone you love, perhaps a Granma, this thought will trigger activity throughout your brain: memories and emotions.  You think about her smell (did she smoke? Maybe she wore Diorella?), and the part of your brain related to smell lights up; you think of the sight of her friendly face, and the vision part of the brain lights up; the feel of her scratchy nylon bedspread; the taste of her apple pie, and those parts also light up.  The emotional parts of your brain are also lighting up with feelings of love or loss or both.  You see, there is no specific ‘Granma’ part of the brain.

Pain is very like this; if you happened to have your head in an FMRI machine and I came along and pinched your bum, your brain would light up all over like a Christmas tree – anger, irritation, fear or even pleasure may feature as strongly as the unpleasant pinching sensation you experience in your bottom (and the fact that it is dark in an FMRI machine and that all you can smell is hospital).  Each different painful experience has its own particular feature of brain points that light up, called a ‘neuro tag’.  The good news is that if we can map a neuro tag we can set about changing it, hopefully for the better.

Neck pain

Imagine you are at home in the evening in your cosy, safe sitting room watching a commentary of the day’s political activity in Westminster.  You get up to make a cup of tea and stub your toe on the leg of the coffee table.

What happens?

Well, the A-delta nociceptive neurons fire off an enthusiastic message to the brain (these nerves are high threshold sensory receptors that are generally influenced by noxious stimuli such as heat, sharp pin pricks and pressure.  They are fast, so the message gets transported quickly despite taking a somewhat convoluted route via the spinal cord and through various parts of the brain, until the message final makes it to your sensory cortex) – “your left big toe has sustained a degree of blunt force trauma!”.  Your brain has to consider this, and whether to do anything about it, so it looks around for help in order to make a decision; smell – tonight’s supper that you have just eaten; sight – that blooming coffee table (you have always hated that coffee table, it was an accident waiting to happen with those stupid, ugly legs – who moved it?!!); feel – other than the screaming sharp pain in your left toe?  You are aware that you feel warm, dry and safe.  Is there anything in your environment more important than the pain in your toe right now?

Next thing you know, you are rolling around in agony from a minor knock to the big toe; you have never experienced pain like it and it’s all that ugly-legged coffee table’s fault!

Eventually the C-fibre nociceptors make it to your brain and finally deliver their message: “there has been some sort of blunt force trauma to the left big toe!”.  These nociceptors tend to throb rather than scream so at this point the pain may ease a tad, but I doubt it; instead you brain is going to punish you for your overreaction with a little bit more pain.  In the situation of your nice, comfortable a safe sitting room where there are few or no distractions, there is nothing more urgent than pain, possibly worsened by your emotional dislike of the coffee table and even the political shenanigans at Westminster!

Now, let’s change the situation; imagine you are trying to cross the road at Trafalgar roundabout.  You are hungry, it’s raining and the light is poor – you see a gap in the traffic and run for it, but halfway across the road you stub your toe.

What happens?

Well, the A-delta nociceptive neurons fire off an enthusiastic message to the brain: “your left big toe has sustained a degree of blunt force trauma!”. Your brain has to consider this and whether to do anything about it, so it looks around for help in order to make a decision; smell – traffic fumes; sight – rain, poor light, traffic (bearing down on you at speed!); feel – rain, cold, hunger, fear…  What is more important, pain in the big toe or saving your life in a dangerous situation?

I can guarantee that you will make it to the other side of the road almost oblivious of that stubbed toe (your brain may allow you to swear under your breath, thus giving you some mild pain relief by activating the amygdala).  By this time, your C-delta nociceptors will have finally managed to get as far as the brain (these guys are slow) with their version of the stubbed big toe – “there has been some sort of blunt force trauma to the left big toe!”. At this point, you may be made aware of the left big toe in the form of a dull throbbing ache; more likely you will notice a bruise a few days later and wonder how you did that.

What I am saying is that the brain is in charge: it will prioritise your life over pain, but in non-life-threatening situations it is not often rational.  Consciously it is possible to distract a brain from pain; simply put a ringing phone into the sitting room scenario and suddenly your curiosity trumps rolling around in agony on the floor – and you may swear a little – but you will manage to check your phone to see if it’s important.

As a chiropractor, it’s my job to work out why you have your pain and what this pain means to you, taking into account your past experience, beliefs and knowledge – “Uncle Ralph had back pain then he was diagnosed with kidney cancer and died”, “my neighbour had sciatica for 20 years and it put her in a wheelchair”, “Dr Google says I have probably got a brain tumour!”. Or perhaps you only have positive knowledge of injuries? – “my dad had a bad episode of back pain but he went and got help and was back at work within a day or two”, “my GP explained exactly why, following taking a good case history and doing a thorough examination, he thought it was really unlikely that I have done anything serious or long lasting to my neck so I’m happy to wait for my body to do its own healing magic and I’m confident I’ll be pain free in a week or so”.  Once I understand your perspective, we can come up with a plan of management that works for you.

Useful link to Neuro Orthopaedic Institute

A great book to take you further along the explain pain pathway The Protecometer 

For some fun stories about Pain

TED talk

Thank you to Katie who helped me to make this make some sense!

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