Thursday, January 17, 2013

‘Measuring Pain: How Much Does It Hurt?’ at the Dana Centre, 16th January 2013



Agonising, torturous, tender, stinging, stiff, thumping, raw, itchy, stabbing, dull, crippling.  We have many words for pain, many ways of trying to put into words a sensation that seems to defy communication.  Asking someone “how much does it hurt?” seems a simple question, but as I learned at the Dana Centre last night, there are innumerable physiological,  psychological and even cultural factors to consider when you’re trying to work out just how much pain someone is in.   Being able to accurately quantify pain is hugely important to medicine, allowing the correct prescription of analgesics and courses of treatment for chronic conditions.

The speakers last night at the Dana Centre came from a variety of medical backgrounds, and all are trying to understand different aspects of pain.  Our facilitator was the charmingly pleasant Tim Crocker-Buque, a junior doctor working in Accident and Emergency at the Royal London Hospital, and the rest of the panel was composed of Matthew Howard, a research scientist from the Department of Neuroimaging at Kings College London; Archie Naughton, a patient liaison representative speaking about his personal experience with pain; Melvin Muzue an Oxford DPhil student researching advanced magnetic resonance imaging of the brain; and Becky Saul, a lecturer-practitioner in paediatric pain at Great Ormond Street Hospital.

http://images2.wikia.nocookie.net/__cb20080206222717/metalgear/images/b/bc/The_Pain.jpg
The Pain!
It’s useful before we begin to pin down exactly what pain is.  Tim Crocker-Buque quotes from the International Association for the Study of Pain Subcommittee on Taxonomy, 1986, telling us:
“Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage.”
It’s an elegant, precise definition, consciously clinical and antiseptic in its language.  Accurate it may be, it begins to seem a little cold when Tim begins to tell us about some of the patients he’s seen in Accident and Emergency over the last week.  People in excruciating pain from kidney stones, back pains rendering people unable to move, rugby players with dislocated joints and most memorably someone who had drunkenly fallen out of a window and impaled their thigh on a fence.  I suspect if you asked any of these people if they were having an ‘unpleasant sensory experience’ you’d get the dirtiest of dirty looks from them.

Trying to get accurate information out of people that are in pain is tricky at the best of times, if they’ve just suffered a serious accident then they’re likely be in a heightened emotional state.  Even if you are totally calm, it can still be frustratingly difficult to translate the exact kind of pain you’re in to a medical professional.  Later in the evening an audience member makes a good point that even if you do explain yourself well, how you know whether the doctor or nurse has really understood what you’re talking about?

A classical 1-10 scale
Traditionally, a 1-10 scale as shown above is used to allow patients communicate their pain.  It’s easy to administer and understand, but also a rather fuzzy and subjectivel.  The problems with it range from assuming numeracy in patients, the ability of the patient to communicate, the emotional state of the patient, and even, fascinatingly, their cultural background.  We’re told how patients from Mediterranean backgrounds will happily and extensively describe exactly how and where their pain hurts, while those from Eastern European backgrounds tend to be taciturn and stoic, declining analgesics or even refusing to admit that they are in pain.

We’re told repeatedly that one of the primary roles of medical professionals is to relieve pain as soon as possible.  When someone comes into A&E in crippling pain, very quickly they’ll be administered analgesics.  I was surprised how readily doctors were willing to administer drugs like morphine to A&E patients, but on reflection they may well have to wait for a period before their injury can be treated.  Personally I’d much rather be in a waiting room full of doped up and dozy injured people rather than on where the air is filled with agonised shrieks.

Quickly knowing what kinds of analgesics to administer becomes very important, and underlines the importance of accurate diagnostic tools.  We’re talked through the ‘Wong-Baker faces’ pain rating scale.  These cartoon faces are an excellent way for children to convey the amount of pain they’re experiencing in a way that eschews language or numeracy.  The scale is flexible enough to allow for children to communicate the levels of emotional pain they feel too, Becky Saul shows us a pretty heartbreaking example of the Wong-Baker scale coloured in by a child at Great Ormond Street, where the most extreme pain is described as equivalent to when his father goes away on an extended business trip.  While these faces are an excellent tool, and are elastic enough to be useful in understanding pain at the opposite end of the age scale in the elderly, it is still subjective, relying on the patients ability to communicate.


The pipe dream of many of the medics here is having an objective way of measuring pain.  There are extremely accurate ways of measuring lots of physiological functions, we’re told how someone can have a sensor placed on their finger that shows precise blood oxygen levels.  The patient can be administered an oxygen feed, and you can view in real time the numbers moving towards a safe level.  The fantasy equivalent for this with pain, as Tim put it, would be a sensor you could slap onto someone’s head that would authoritatively tell them that the person is experiencing a pain level of, say, 7.8.  Treatment could then be administered, and the doctors could watch the numbers fall.

This is currently science fiction, the closest realistic version being found in neuroimaging research using MRI machines that let us see how the human brain functions when the patient is experiencing pain.  Blood has the useful property of being magnetic due to the presence of iron in haemoglobin.  This allows us to see which areas of the brain ‘light up’ with increased blood flow during a painful experience.  Much research into this in the 20th century was focussed on trying to identify a ‘pain centre’ in the brain.  The existence of a single part of the brain that governs pain is a sensible prediction to make; senses like vision and hearing only stimulate certain areas.  But as the MRI researchers on the panel tonight explained, physical suffering activates many different areas of the brain – what is referred to as a ‘pain matrix’.

That we are on the cusp of being able to objectively say whether a patient is in pain or not raises some tricky ethical issues.  What do you do if the situation arises where a patient insists they’re in agony and yet an MRI shows no signs of it?  Is it right to ever assume they’re lying?  Similarly, what do you do if someone claims to be perfectly fine, and yet their brain scan shows the ‘pain matrix’ lighting up?  At the moment these are hypothetical problems, but soon enough they won’t be, and the medical profession will have to wrestle with some pretty tricky dilemmas.

The 'Pain Matrix'

Even if you could objectively detect pain within a patient, you still have to treat it.  It's underlined that there's many factors that affect pain.  These range from the context the pain is felt in to the emotional state of the patient and their cognitive abilities.  Apparently, if a patient is depressed, they will tend to experience higher levels of pain than if they were happy.  Excitement or danger can also influence the sensation of pain, if someone is pumped full of adrenaline then even the pain from a sudden massively traumatic injury like a lost limb can be temporarily suppressed.

This exploitation of the patient’s state of mind, getting them to focus on something other than the pain seems to be very useful.  In Great Ormond Street, when an injured child is brought in by helicopter they’re quite rightly often terrified of what’s going on around them.  The best tactic to calm them down is, apparently to give them an iPad to use, presumably a few sessions of ‘Angry Birds’ doing an awful lot to provide a familiar distraction for a traumatised child.

Conscious and unconscious mental exercises designed to relieve or suppress pain aren’t fully understood, but they seem an excellent unobtrusive way to work with chronic pain.  Our speaker from the patient’s perspective, Archie Naughton, lost his lower leg in a car accident in 1976.  He’s suffered phantom pain, sensations that the body perceives as coming from the missing limb.  He describes these as being equivalent to someone cutting through his flesh with a rusty knife.  This is a classic example of pain being experienced with no obvious physiological cause.  So if there is nothing ‘wrong’ with Archie, how can this pain be relieved?

He tells us about his mental exercises to diminish the pain, ‘forcing’ it into another part of his body and telling himself not to worry about it.  It’s an admirable example of the brain’s ability to consciously repress neurological signals.  Exercises like this are fantastically useful, especially as Naughton has had bad experiences with painkillers in the past.  He tells us of his unpleasant experiences with Tramadol, which he was prescribed after suffering from kidney stones.  The notion of having to weigh up which is more important, pain relief or undergoing unpredictable and unpleasant mood and personality changes is a difficult one, to say nothing of the prospect of quickly developing a physical dependency on painkillers.

A cartoon illustrating common sensations of phantom pain.  From 'A Gimp's Guide to the 801' 
Pain is the root cause of some of the most insidious misery a human being can go through.  If depression is linked to pain then it seems to me to inevitably lead to a pretty horrible spiral.  You feel depressed, so you feel pain, which makes you more depressed and so on.  If you see nothing in the future but chronic pain, with no relief in sight then it’s not surprising that many sufferers commit suicide. 

Conversely, pain is a sensation that keeps you alive.  It’s a warning signal that something is wrong with you, an affirmation of life.  There’s a genetic condition called congenital analgesia where the sufferer does not feel physical pain.  These people do not tend to live very long, commonly biting off their tongues, breaking bones and not being able to detect pain from severe diseases, delaying treatment.  So next time you stub your toe and dance around angrily berating the sky, take a moment afterwards to appreciate the fact that you can feel it.

When it comes to really understanding the ethics of treating pain, I like this 1968 quote from Margo McCaffery, pioneer in pain management:
“Pain is whatever the experiencing person says it is, existing whenever and wherever the person says it does.”
Even though we may not understand the causes, mechanisms or psychology of why someone is feeling pain, it doesn’t make that person’s individual pain any less valid.  With this in mind, the intelligence, good humour and strong sense of empathy with their patients that I saw from the speakers tonight is immensely heartening.

Thanks to everyone who organised this at the Dana Centre, and please let me know if I’ve made any factual errors in the comments.

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