Why We Can't Trust Pain

Kate Roach

June 2002

The air was thick with the whir of enemy fire. A shell exploded nearby. A searing pain shot up his leg and he felt the warm trickle of blood. He passed out and awoke in the medical station. He had been hit – on his canteen. He was sent back out. More shells, more explosions. A sudden excruciating pain ripped through his head. Blood poured into his eyes, blocking his vision. Back at the medical station the doctor picked out a few small pieces of shrapnel from his forehead, patched him up and sent him back out. He stepped forward with as much positive energy as he could muster. Suddenly he was rocked backwards by a massive explosion, this time there was no pain. His leg had been torn off.

This was the harrowing experience of a young US soldier in Vietnam. It shows us just how inconsistent pain can be. Many of us hold the belief that pain is a necessary evil that warns us of injury – this is the classical theory of pain. But our Vietnam soldier teaches us that pain is a very unreliable warning system.

We can read a description of the classical understanding of pain in many biology textbooks. It's often described simply as a reflex response involving, say, the withdrawal of a hand from a fire. In this conception there is a dedicated 'pain pathway' – a nerve that passes from the burnt hand to the spinal cord, where it splits into a T-junction. One branch of the T-junction goes to a supposed 'pain centre' in the brain where the sensation of pain is created. The other branch returns to the hand causing it to withdraw. This suggests a dedicated, hard-wired system of nerves that deal just with pain.

But pain research is showing there is no hard-wired system dedicated just to pain. The nervous system, which includes all our nerves, spinal cord and brain, works together, along with the environment, to create a feeling of pain, or an absence of pain, that fits the present situation.

We all know pain, we have all experienced it and we will all experience it again, but we all have hidden assumptions about it that we rarely examine. Our misconceptions may not help much when it's our turn to be in pain next.

Pain is not predictable

You slip on an uneven paving stone and twist your ankle. Immediately, you get a sharp stabbing pain in it. You believe that your ankle is sending a message to your feeling, thinking self, telling you that it's damaged. The pain in your ankle demands your attention. You're forced to stop walking and examine it. It's beginning to swell and throb. You decide to take a taxi home and rest your ankle.

Now imagine another scenario. You are running away from a building that's on fire, and you injure your ankle in exactly the same way. This time you only feel a tiny stab because you are so focussed on getting away from the fire. You are up and running again within seconds. Is your ankle still sending a message to your feeling, thinking self telling you that it is damaged? Probably, but your nervous system is responding to a more urgent agenda and has overridden the pain in favour of escaping from the fire.

Pain is not simply a fixed message that travels along a nerve from an injured body part to a passive receptive brain. If pain did work in this way it would be like the dial on a car dashboard that tells you when the engine is overheating. The 'pain dial' would always reflect the level of damage whether or not there was a fire to escape from. The problem with thinking about pain in this way is that we tend to assume that severe pain equals severe injury, but this is not the case. It's far more complex. Our perception of pain changes with the particular circumstances we are experiencing at the time.

Fear and anxiety intensify pain

A recent study conducted in Texas, USA by Dr Mary Meagher established that certain emotional states impact on pain perception. She was particularly interested in how the states of fear and anxiety influence pain. Though they might seem similar the two states do differ. Fear is a response to immediate danger – it prepares us for escape or defence. Anxiety is concern for the future – in our anticipation we become extra sensitive to what is happening both inside and outside our bodies.

There were 120 human volunteers in the study, each of whom completed the same initial procedure. Firstly, a measure of pain threshold was recorded in each subject, by monitoring the time taken for a heat lamp to produce pain in a finger. The volunteers were then split into three groups and wired up to an electric shock generator. Dr Mary Meagher explains how she was able to induce fear or anxiety in her subjects.

'We had one group called our 'fear' group – we exposed them to three brief, unexpected, slightly painful electric shocks. The second group was the 'anxiety' group – they were told they may or may not receive slightly painful electric shocks. But they never did, so they spent the session wondering when this awful thing was going to happen and dealing with the uncertainty of that event. The third group received no electric shocks and no warnings of shocks.'

At the end of the session each volunteer was subjected to another heat lamp test. The pain threshold measurements taken before and after the experiment were compared.

'We found that fear facilitated an analgesic state. These subjects were less sensitive to the heat lamp tests that were administered after the shocks were presented so they showed reduced pain sensitivity. In contrast, the subjects that were exposed to the threat of shock but never actually received the shock showed enhanced pain sensitivity.'

Dr Meagher's research has huge implications for the way we deal with pain in ourselves and in others. It tells us that pain shouldn't be treated as a symptom that is isolated from the whole person. To help cope with pain we need to ask ourselves 'Is this pain really telling me I'm hurt?' Because most of us believe that pain is bad news and that bad pain equals bad injury, anxiety is a common response. And, as Dr Meagher's experiment showed, anxiety makes the pain worse.

Angina and anxiety

Dr Mike Chester, Director of the National Refractory Angina Centre, commonly comes across this anxiety problem in angina patients. Many wrongly believe that each time they get an angina attack it's doing them harm. He gives an example of how these mistaken beliefs can paralyse someone and destroy their life.

'A patient I see told me of her concern that she is getting angina very frequently. She believes that each angina attack is wearing her heart out. She feels as though she's standing by the edge of a cliff and she can hear the waves crashing at the bottom, but she's got a blindfold on so she doesn't know how close she is. Every time she gets an angina attack someone gives her a little nudge in the back pushing her closer to it. She has five of those attacks a day, and each time she gets one she gets really anxious.

Well, a much more accurate situation is that each time she gets angina she produces an extra little bypass that nourishes her heart with blood. So what's really happening is that each time she has angina, someone's giving her a pound and pulling her away from the edge. And so for five or six years she has lived with the unbearable anxiety of believing she's going towards the edge of cliff, when in fact she's being eased away from it. She left the clinic feeling completely different about it all and her pain has become much easier to bear, even lessened a little.'

Phantom pain

If our state of mind can influence the intensity of our pain so effectively, it suggests that the brain plays a key role in creating pain. This is indeed the case. And the brain's role in pain production is particularly evident when a limb is amputated. The initial pain following amputation is a result of tissue damage, but after that a curious situation arises – a phantom limb develops. A clear sensation is produced that in every detail feels as though the amputated limb is still present.

Many of us will have experienced a phantom. Go to the dentist, have a local block and you have a numb lip. The anaesthetic blocks the nerve impulses running from the lip to the brain. As far as the brain is concerned, the lip is no longer there. But the sensation we tend to experience isn't a hole in the face, it's a lip that feels swollen and out of place. That's a phantom lip. The brain is continually monitoring the input from all of our different parts – if a part disappears the brain attempts to put the feeling back.

This happens on a larger scale with amputated legs, arms and breasts. It usually remains as a painless phantom, but in more than 70% of amputees the excitability of the nerve cells grows and grows to the point where they're beginning to fire just by themselves. This spells trouble. It results in persistent pain long after the tissue damage has healed. One avenue of research has shown that nerves in the spinal cord respond to injury by becoming hypersensitive. It explains why sunburnt skin is so sensitive and why bruises ache, but mostly sensitisation calms down after the injury has healed. Researchers are turning to the brain to try and understand what happens when sensitivity of some nerves cranks up the pain permanently.

Neuroscientists have long suspected that the sudden absence of nervous input from a missing limb results in a permanent re-wiring of nerves in the brain. This idea followed the common observation that stroking the face can often produce sensation in a missing arm. Nerves from the face enter the brain adjacent to nerves from the arm, so could facial nerves encroach on the nerves that used to end in the arm? Researchers in Tennessee, USA, have shown that this kind of re-wiring does occur in monkeys. although it has yet to be shown in people, this may prove to be a fruitful avenue.

Phantom pain varies from person to person. Some feel steady aches, others have pins and needles and some feel as though the missing limb is in a permanent state of cramp. This kind of pain is difficult to treat and hard to live with. It can happen in any situation in which nerves are damaged and cease to send incoming messages to the brain. The name given to pain that is caused by nerve damage is neuropathic pain. Such pain can also be caused by diseases that damage nerves like shingles, diabetes and some cancers.

The quest for treatment of neuropathic pain is still a hot area of pain research. At the moment unexpected drugs are being used, like anti-depressants. Modern anti-depressants increase the amount of a chemical in the brain called serotonin – a positive mood enhancer. Serotonin is also active in one of the systems by which the brain controls the nerve impulses that arise in the spinal cord and signal injury to the brain. Anti-depressants can help to decrease the signal from the spinal cord to the brain and improve pain relief.

When pain is useful

Research shows us that in most cases pain is a fairly unreliable indicator of the extent of physical damage. It can persist long after an injury has healed and it can be absent at the point of severe injury. It can alter with our mood and it can trap us into ever decreasing circles of anxiety, inactivity and despondency. So is pain ever useful?

Well, take this example. If you slip off the curb and twist your ankle you will feel two separate sensations. At the moment of the twist, there's a sharp cutting pain in your ankle and you are aware you have hurt yourself. After a couple of hours have passed a quite different sort of pain sets in. It's deep, it's spreading, it's sore, it's sickening, and it involves not just your ankle but the whole foot and leg. That second phase of pain is crucial because it keeps you from walking on your ankle. Your natural instinct is to guard it and let no one touch it. This kind of pain is very important in allowing an injury, even if minor, to heal.

Very rarely there are people born unable to feel pain of any description. They have a condition called congenital analgesia. In all other respects they are completely normal. Helen James has this condition. She is 30 years of age and has never felt pain in her life. She says it was excellent not feeling pain as a kid and thinks that you don't need pain in most situations to tell that you're injured. She feels the heat of a burn and the bang of stubbed toe, but not the pain; the fever of flu, but not the aches and pains. So she has plenty of indicators to tell her when she is hurt. But she has one problem – she misses the secondary phase of pain that would prevent her from walking on an injured joint or a broken bone before it has healed.

'As a kid I had lots and lots of broken bones, and they never hurt at all. The problem was that I used to keep walking on them and make them worse. Once I went to hospital to have a plaster taken off my leg, and when it came off the leg was swollen and they found I'd broken it again while it was in plaster. I was gutted, I had to go back in plaster.'

From what she understands about pain, Helen is quite happy not to have it, except for the fact that as a child she did permanent damage in her joints.

'My joints are basically knackered, to all intents and purposes they're knotted really. My ankle joints are the worst and my knee joints are pretty bad. I presume I'll get arthritis soon. At least it won't hurt.'

Helen shows us that pain does have a useful role. It stops us from using an injured body part before it has had chance to heal. It's possible to live without the immediate stab of pain from a fall or burnt finger as there are other indicators to tell you that you're injured. But the longer, secondary phase of pain is essential to stop us from using an injured body part before it has had chance to heal. But this is the only useful period of pain. Cancer pain, heart pain, back pain, migraines and all sorts of other aches and pains don't have a protective role like the pain of sprained ankle. In fact, quite the opposite, they can be damaging.

The field of pain research has moved on from seeing pain as a simple system of nerve impulses, and it no longer treats all pains as if they are the same. Now, with a greater understanding of the role of the brain in creating pain, there is hope that many of our useless pains will be placed firmly in the past.

Find out more

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Websites

Pain Concern
www.painconcern.org.uk
UK charity offering information and support. Free leaflets can be ordered online and the website has details of a helpline for sufferers.

Pain.com
www.pain.com
Has lots of information and articles on pain and pain management.

Pain Support
www.painsupport.co.uk
Jan Sadler, author of Natural Pain Relief, promotes a multi-disciplinary approach, where conventional medicine and complimentary therapies work side-by-side. Contains useful information for sufferers and their families and friends.

Pain Association Scotland
www.painassociation.com
Offers supports for those with chronic pain, based in Scotland.

The Pain Web
www.thepainweb.com
This website is for health professionals dealing in research, assessment and treatment of pain. There are some excellent articles and lots of information on drugs.

Chronic Refractory Angina
www.angina.org
Contains everything you need to know about angina. For patients, carers, nurses and other clinicians.

CancerBACUP
www.bacup.org
Advice, information and support services about cancer.

Pain FAQs
What is pain? Do women feel more pain than men? Some of your most frequently asked questions answered here.

Controlling the Pain of Cancer and Heart Disease
The pain of cancer and heart disease is useless and in the long run it's damaging. Find out why you shouldn't just grin and bear it and what the options are for pain relief.

Angina
Article for angina sufferers.

Books

	Cancer Pain Management by Karen Simpson Cancer-related pain can be successfully managed in the majority of patients with the use of medication. Some patients, however, have pain that doesn't respond to narcotics, and require more specialised pain management techniques. Examples of such treatments are nerve blocks, radiotherapy, acupuncture and physiotherapy. This book focuses on alternative methods of pain management. Get this book
	Pain: The science of suffering by Patrick Wall This is a wonderful book written by a pain researcher with 50 years experience. Written for the layperson, it will give you a wonderful insight into the world of pain research. One of the most human of science books you'll find on the shelves at the moment. Shares a viewpoint with this article. Get this book
	Coping Successfully with Pain by Neville Shone Looks at the multiple causes of pain, examines the distinction between acute and chronic pain, and gives advice on the use of drugs, the work of the Pain Clinic and the need for physical exercise and relaxation. The book also explains the debilitating effects of long-term pain. Get this book
	Handbook for Pain Management by Ruth Kingdon et al This is a quick-reference handbook which features practical 'how-to' pain management strategies for all patient populations with separate chapters for the elderly, infants and children, substance abusers, cancer and AIDS patients. Get this book
	Pain – Its Nature and Management by Nicky Thomas This holistic textbook addresses the nature of pain and its management. It includes chapters on specific pain types such as cancer pain and sickle cell disease pain. It also contains chapters on specific groups: children and the elderly. Get this book
	A Referred Pain: Reflections on family life and cancer by Penny Snow At the age of 21, Penny Snow watched her father die – a victim of colon cancer. Fourteen years later she witnessed her mother's death from the same disease. This book aims to confront difficult emotions, and to help those who have lived or are living in similar situations. Get this book
	Reader's Digest Health and Healing the Natural Way: Managing pain Fear and lack of information are the chief barriers to the control of pain. This book uses clear information to help banish fear, and it explains the positive role that pain plays in the functioning of the body. It also suggests self-help measures and alternative therapies where appropriate. Get this book
	Healing Back Pain Naturally by Art Brownstein The author spent 20 miserable and almost suicidal years suffering acute back pain. He permanently cured himself and has cured thousands of others using his programme. This book explains how it works. Get this book
	Overcome Neck and Back Pain by Kit Laughlin This text presents a different approach to the self-treatment of neck and back pain. It offers an easy-to-learn programme that combines Eastern and Western healing practices, drawing on traditional hatha yoga, the contract-relax method of stretching and a selection of strengthening exercises. Get this book
	Massage for Pain Relief by Peijian Chen The Chinese understanding of health is based on the circulation of Qi (energy). If energy is low or becomes blocked it stagnates, leading to illness. Pressure point massage improves circulation of stagnated energy by working along energy channels. This book offers on-the-spot relief for toothache, headaches, shoulder pain and neuralgia, and there are sequences of massage strokes to relieve pain which seems out of reach – such as gastric ulcers and arthritis. Get this book
	Prolo Your Pain Away by Ross and Marion Hauser Prolotherapy is a simple, safe technique, which stimulates the body's healing mechanisms to grow new ligament and tendon tissue. It's claimed that the technique provides a permanent cure for many painful chronic conditions, such as back pain and arthritis. This book shows how the method works. Get this book
	Chest Pain by Richard Becker The wide range of conditions responsible for chest pain make it difficult to determine the single underlying cause and to decide upon the best possible plan of treatment. This is a quick-access handbook that includes chest pain in all adults and from all causes, in a pocket size reference format. It includes immediate assessment and treatment of acute causes of chest pain. Get this book

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