How can doctors measure pain? For Mosaic , John Walsh finds out about new ways of assessing the agony. His story is republished here under a Creative Commons license.

One night in May, my wife sat up in bed and said, “I’ve got this awful pain just here.” She prodded her abdomen and made a face. “It feels like something’s really wrong.” Woozily noting that it was 2am, I asked what kind of pain it was. “Like something’s biting into me and won’t stop,” she said.

“Hold on,” I said blearily, “help is at hand.” I brought her a couple of ibuprofen with some water, which she downed, clutching my hand and waiting for the ache to subside.

An hour later, she was sitting up in bed again, in real distress. “It’s worse now,” she said, “really nasty. Can you phone the doctor?” Miraculously, the family doctor answered the phone at 3am, listened to her recital of symptoms and concluded, “It might be your appendix. Have you had yours taken out?” No, she hadn’t. “It could be appendicitis,” he surmised, “but if it was dangerous you’d be in much worse pain than you’re in. Go to the hospital in the morning, but for now, take some paracetamol and try to sleep.”

Barely half an hour later, the balloon went up. She was awakened for the third time, but now with a pain so savage and uncontainable it made her howl like a tortured witch facedown on a bonfire. The time for murmured assurances and spousal procrastination was over. I rang a local minicab, struggled into my clothes, bundled her into a dressing gown, and sped to St. Mary’s Paddington just before 4am.

The flurry of action made the pain subside, if only through distraction, and we sat for hours while doctors brought forms to be filled, took her blood pressure, and ran tests. A registrar poked a needle into my wife’s wrist and said, “Does that hurt? Does that? How about that?” before concluding: “Impressive. You have a very high pain threshold.”

The pain was from pancreatitis, brought on by rogue gallstones that had escaped from her gall bladder and made their way, like fleeing convicts, to a refuge in her pancreas, causing agony. She was given a course of antibiotics and, a month later, had an operation to remove her gall bladder.

“It’s keyhole surgery,” said the surgeon breezily, “so you’ll be back to normal very soon. Some people feel well enough to take the bus home after the operation.” His optimism was misplaced. My lovely wife, she of the admirably high pain threshold, had to stay overnight and came home the following day filled with painkillers; when they wore off, she writhed with suffering. After three days she rang the specialist, only to be told: “It’s not the operation that’s causing discomfort—it’s the air that was pumped inside you to separate the organs before surgery.” Like all too many surgeons, they had lost interest in the fallout once the operation had proved a success.

During that period of convalescence, as I watched her grimace and clench her teeth and let slip little cries of anguish until a long regimen of combined ibuprofen and codeine finally conquered the pain, several questions came into my head. Chief among them was: can anyone in the medical profession talk about pain with any authority? From the family doctor to the surgeon, their remarks and suggestions seemed tentative, generalised, unknowing—and potentially dangerous: was it right for the doctor to tell my wife that her level of pain didn’t sound like appendicitis when the doctor didn’t know whether she had a high or low pain threshold? Should he have advised her to stay in bed and risk her appendix exploding into peritonitis? How could surgeons predict that patients would feel only ‘discomfort’ after such an operation when she felt agony—an agony that was aggravated by fear that the operation had been a failure?

I also wondered if there were any agreed words that would help a doctor understand the pain felt by a patient. I thought of my father, a GP in the 1960s with an NHS practice in south London, who used to marvel at the colourful pain symptoms he heard: “It’s like I’ve been attacked with a stapler;” “like having rabbits running up and down my spine;” “it’s like someone’s opened a cocktail umbrella in my penis...” Few of them, he told me, corresponded to the symptoms listed in a medical textbook. So how should he proceed? By guesswork and aspirin?

There seemed to be a chasm of understanding in human discussions of pain. I wanted to find out how the medical profession apprehends pain—the language it uses for something that’s invisible to the naked eye, that can’t be measured except by asking for the sufferer’s subjective description, and that can be treated only by the use of opium derivatives that go back to the Middle Ages.

On a scale of 1-to-ouch

When investigating pain, the basic procedure for clinics everywhere is to give a patient the McGill Pain Questionnaire. This was developed in the 1970s by two scientists, Dr. Ronald Melzack and Dr. Warren Torgerson, both of McGill University in Montreal, and is still the main tool for measuring pain in clinics worldwide.

Melzack and his colleague Dr. Patrick Wall of St. Thomas’ Hospital in London had already galvanised the field of pain research in 1965 with their seminal ‘gate control theory,' a ground-breaking explanation of how psychology can affect the body’s perception of pain. In 1984 the pair went on to write Wall and Melzack’s Textbook of Pain, the most comprehensive reference work in pain medicine. It’s gone through five editions and is currently over 1,000 pages long.

In the early 1970s, Melzack began to list the words patients used to describe their pain and classified them into three categories: sensory (which included heat, pressure, ‘throbbing’ or ‘pounding’ sensations), affective (which related to emotional effects, such as ‘tiring,' ‘sickening,' ‘gruelling’ or ‘frightful’), and lastly evaluative (evocative of an experience—from ‘annoying’ and ‘troublesome’ to ‘horrible,' ‘unbearable,’ and ‘excruciating’).

You don’t have to be a linguistic genius to see there are shortcomings in this lexical smorgasbord. For one thing, some words in the affective and evaluative categories seem interchangeable—there’s no difference between ‘frightful’ in the former and ‘horrible’ in the latter, or between ‘tiring’ and ‘annoying'—and all the words share an unfortunate quality of sounding like a duchess complaining about a ball that didn’t meet her standards.

But Melzack’s grid of suffering formed the basis of what became the McGill Pain Questionnaire. The patient listens as a list of pain descriptors is read out and has to say whether each word describes their pain—and, if so, to rate the intensity of the feeling. They then look at the questionnaire and put check marks in the appropriate places. This gives the clinician a number, or a percentage figure, to work with in assessing, later, whether a treatment has brought the pain down (or up).

A more recent variant is the National Initiative on Pain Control’s Pain Quality Assessment Scale (PQAS), in which patients are asked to indicate, on a scale of 1 to 10, how intense or sharp, hot, “dull, cold, sensitive, tender, itchy, etc. pain has been over the past week.

The trouble with this approach is the imprecision of that scale of 1 to 10, where a 10 would be “the most intense pain sensation imaginable." How does a patient imagine the worst pain ever and give their own pain a number? Middle-class British men who have never been in a war zone may find it hard to imagine anything more agonising than toothache or a tennis injury. Women who have experienced childbirth may, after that experience, rate everything else as a mild 3 or 4.

I asked some friends what they thought the worst physical pain might be. Inevitably, they just described nasty things that had happened to them. One man nominated gout. He recalled lying on a sofa, with his gouty foot resting on a pillow, when a visiting aunt passed by; the chiffon scarf she was wearing slipped from her neck and lightly touched his foot. It was “unbearable agony." A brother-in-law nominated post-root-canal toothache—unlike muscular or back pain, he said, it couldn’t be alleviated by shifting your posture. It was “relentless." A male friend confided that a haemorrhoidectomy had left him with irritable bowel syndrome, in which a daily spasm made him feel “as if somebody had shoved a stirrup pump up my arse and was pumping furiously." The pain was, he said, “boundless, as if it wouldn’t stop until I exploded.” A woman friend recalled the moment the hem of her husband’s trouser leg snagged on her big toe, ripping the nail clean off. She used a musical analogy to explain the effect: “I’d been through childbirth, I’d broken my leg—and I recalled them both as low moaning noises, like cellos; the ripped-off nail was excruciating, a great high deafening shriek of psychopathic violins, like nothing I’d heard or felt before.”

A novelist friend who specialises in World War drew my attention to Stuart Cloete’s memoir, Victorian Son, in which the author records his time in a field hospital. He marvels at the stoicism of the wounded soldiers: “I have heard boys on their stretchers crying with weakness, but all they ever asked for was water or a cigarette. The exception was a man hit through the palm of the hand. This I believe to be the most painful wound there is, as the sinews of the arm contract, tearing as if on a rack.”

Is it true? Looking at the Crucifixion scene in Matthias Grünewald’s Isenheim Altarpiece (1512-16), you take in the horribly straining fingers of Christ, around the fat nailheads that skewer his hands to the wood—and oh God yes, you believe it must be true.

It seems a shame that these eloquent descriptions are reduced by the McGill Questionnaire to words like ‘throbbing or sharp," but its function is simply to give pain a number—a number that will, with luck, be decreased after treatment, when the patient is reassessed.

This procedure doesn’t impress Professor Stephen McMahon of the London Pain Consortium, an organisation formed in 2002 to promote internationally competitive research into pain. “There are lots of problems that come with trying to measure pain,” he says. “I think the obsession with numbers is an oversimplification. Pain is not unidimensional. It doesn’t just come with scale—a lot or a little—it comes with other baggage: how threatening it is, how emotionally disturbing, how it affects your ability to concentrate. The measuring obsession probably comes from the regulators who think that, to understand drugs, you have to show efficacy. And the American Food and Drug Administration doesn’t like quality-of-life assessments; they like hard numbers. So we’re thrown back on giving it a number and scoring it. It’s a bit of a wasted exercise because it’s only one dimension of pain that we’re capturing.”

Listing image by Flickr user: Puno 3000