Pain In The Brain

May 1, 2006 by Natalie Salat

Pain really is all in the mind–well, the brain, actually. When you slam your finger in the car door, though it is your finger that may be throbbing, how you perceive and react to that pain–fainting, swearing, jumping out of your skin–depends on what is going on upstairs. “To be exact, all pain perception is in the brain,” points out pain specialist Dr. Angela Mailis-Gagnon. How you experience chronic pain–pain that persists for more than six months–and how you respond to different treatments also depends on that mix of physiological, psychological and social factors that makes you you. Pain, in other words, is a highly subjective experience.

ILLUSTRATION: SCOTT PAGE

ILLUSTRATION: SCOTT PAGE

Regardless of what may be the cause of their pain, many people look to over-the-counter medications for relief. Aspirin (such as Bayer), acetaminophen (such as Tylenol) and ibuprofen (such as Advil)–three of the most common kinds of non-prescription painkillers–can be effective, safe and cost-effective when taken as directed. However, there is potential for misuse and overuse. Seniors need to be especially careful about dosage, as intolerance to drugs increases with age. Among the common side-effects are gastrointestinal bleeding and liver and kidney damage.

Traditionally, doctors have been better at dealing with acute pain, which tends to have a physical cause, says Mailis-Gagnon, who established the comprehensive pain program at Toronto Western Hospital more than 20 years ago. “Acute pain is not easily dismissed. This is why God has given us pain–to tell us something is wrong with the body.”

The puzzle gets more complicated when it comes to chronic or recurring pain. Mailis-Gagnon sees the most complex cases, where there is often no visible or detectable cause. “With chronic or recurring pain, the picture is much more fuddled because there could be a lot more things going on than just the physical part.”

Such is the case for Mary Lou Wood. Now housebound, the 50-something Ottawa resident had been an avid dancer and performer well into her 40s. By then, she had a teenaged daughter to look after on her own; she was also working full time and upgrading her college education with business and computer courses. “I felt like a supermom, in great health and good shape.”

After two years on this track, though, “I awoke one morning feeling like I couldn’t get going, physically or mentally.” Within six months her whole body was wracked with pain. Her doctor diagnosed her with fibromyalgia–marked by widespread musculoskeletal pain–and chronic fatigue syndrome.

She believes her condition was triggered by unresolved emotional issues. “I’ve had a lot of traumas in my life, which I thought I’d dealt with.” Despite changes to her lifestyle and countless visits to neurologists, psychiatrists and other specialists, Wood developed another chronic pain condition called reflex sympathetic dystrophy (RSD), stemming from a dance injury she had sustained to her foot. This neurological syndrome–with its attendant burning pain, tissue swelling and extreme sensitivity to touch–has left her virtually incapacitated. “Your whole being–body, mind and soul–is affected,” she says.

Many pieces of the pain puzzle, such as how conditions like Wood’s develop, and how acute pain becomes chronic, have yet to be solved. However, pain specialists and clinicians have been able to unravel considerable chunks over the last 15 years thanks to advances in imaging technology, which have made it possible to see the brain in action without resorting to the scalpel. Canadians have historically been at the forefront of pain research.

Last year, a cross-Canada effort supported by the NeuroScience Canada Brain Repair Program discovered a key mechanism behind neuropathic pain. This debilitating form of chronic pain–RSD is one example–is caused by nerve damage and does not respond to any available drug treatment, not even morphine.

This discovery will help researchers develop diagnostic tools and drug treatments that could allow sufferers like Wood to become active again. It could not have come about, however, without a prior Canadian/British breakthrough. In the mid-1960s, Dr. Robert Melzack of McGill University in Montreal and his British collaborator, neuroscientist Dr. Patrick Wall, came up with an explanation of pain that revolutionized the field.

Until then, it had been believed that pain messages travelled on a linear path, from receptors in the skin, muscle, joint or organ via a nerve to the spinal cord, and then up to the brain. It was also thought there was a direct relationship between tissue damage and how much pain was felt–the more damage, the more pain. The experience of World War II veterans helped dispel this idea, as doctors found that some veterans were suffering more than could be explained by the tissue damage alone.

Melzack and Wall’s “gate control” theory held that pain perception depends on the interplay between the peripheral nervous system–nerves extending from the spinal cord to the skin, muscles or internal organs–and the central nervous system (the spinal cord and brain). Not only did they quash the idea that pain takes a one-way route, but they also explained that pain signals are changed by influences from the brain and from other non-pain signals from elsewhere in the body.

Though modified slightly over the years, the gate control theory still holds. Crucial to the theory is the fact that peripheral nerve fibres, which bunch together to form nerves, come in different sizes and conduct messages to the brain at different rates. Some nerve fibres respond to touch, pressure and temperature, while others end with receptors that detect tissue damage, called nociceptors. There are millions of nociceptors in the body, with the highest concentration being in areas prone to injury, such as fingers. Sharp, stabbing pain is transmitted along the speedy A delta nerve fibre, while dull, throbbing aches are transmitted along the slower C fibre.

In response to a harmful stimulus, such as the cut of a knife, the nociceptors relay pain signals–in the form of electrical impulses–along the peripheral nerve fibres to the dorsal horns of the spinal cord. Here, they meet with specialized cells that act as gatekeepers, filtering the pain messages on their way to the brain. With severe pain messages, such as when you touch a piping hot stove, the gate opens wide to allow the message to zip to the brain’s switchboard, the thalamus. The thalamus then sends the message on to the somatosensory cortex, the limbic system and the frontal cortex, which are responsible for physical sensation, emotion and thought, respectively.

While all this is going on, a series of reactions is taking place at the site of injury to cause inflammation, which brings on pain and swelling but also increases blood flow and promotes healing. The brain is meanwhile relaying messages of its own. Just what those signals are–such as ordering the release of the body’s own pain-blocking chemicals–depends not only on genetic makeup, but on age, gender, cultural experiences, upbringing and emotional state.

For instance, anxiety can amplify pain by provoking the body’s ‘fight or flight’ response, causing the hormones adrenalin and noradrenalin to circulate. “They actually increase pain transmission, particularly in a nerve that has been damaged,” says Dr. Patricia Morley-Forster, medical director of the interdisciplinary pain program at the University of Western Ontario’s Schulich School of Medicine and St. Joseph’s Health Care in London, Ont. “If you’re anticipating something’s going to give you a lot of pain, you’ll generally have more pain than if you prepare yourself that something is not going to hurt. The anticipation response is a physiological (process) of increasing your own pain-killing substances to block incoming messages.”

In her work, Morley-Forster is especially interested in harnessing the placebo response, which is a beneficial response to treatment that cannot be explained by the treatment alone. “Every therapy–whether it is touch, massage, acupuncture or pills–always has a placebo component that the patient brings to it. We should try to enhance it as much as possible and convince people that it is more their own natural healing capability. ”

To do that, “you have to try to find out what’s driving (the patient),” she says. “The more the patient feels the doctor understands what their goals are, the better the therapeutic response they will have.”

Mailis-Gagnon, whose popular science book, Beyond Pain, explored the connection between mind and body, advocates a ‘biopsychosocial’ approach to pain. “You have to look carefully at the (whole) person. The emotional component (to pain) is so huge. This is how people with the same physical pathology have very different reactions. People from certain cultures are much more stoic in presenting their problems, while others from different cultures are more flamboyant.”

A person’s environment, how much attention they give to their pain, as well as previous memories and experiences all colour their response to pain. When diagnosing her patients and determining a course of action, Mailis-Gagnon takes into account the gamut of physical, psychological and social factors. Often, a combination of medication and psychological treatment is required.

While not all cases are as difficult to decipher as Wood’s, chronic pain is a fact of life for between 20 to 30 per cent of Canadians, according to a wide-ranging 2002 study by neurologist Dr. Dwight Moulin of the London Health Sciences Centre in Ontario. The rate climbs to almost 40 per cent in adults 55-plus, in forms such as back pain, arthritis and cancer pain. Besides the toll on individual lives, including social isolation and inability to carry out daily tasks, the economic cost is massive; the Canadian Pain Society estimates it to be $6 billion a year, including missed work days and increased use of the health-care system.

Until the last five years, chronic pain did not get much attention at medical schools either, dismissed–for all the wrong reasons–as being “all in the head.” While this attitude is changing, the health-care system still has a ways to go in providing adequate attention to chronic pain.

Mailis-Gagnon, a high-energy individual who immigrated to Canada from Greece and raised two sons while finishing several medical degrees, had to fight to make her pain program a permanent fixture at her hospital. Her program includes pain specialists, psychiatrists, other health professionals and in-patient beds. But overall, she says bluntly, “pain facilities throughout the country suck.” She has formed an association with other pain clinic directors in Ontario to advocate for more multidisciplinary pain facilities.

Some provinces and territories, namely P.E.I., Nunavut and the Yukon, do not have a single comprehensive pain program. Saskatchewan, Manitoba, New Brunswick and Newfoundland each have one publicly funded program, while the average waiting list for chronic pain treatment elsewhere in Canada ranges from 14 months in Alberta to 26 months in Ontario, to 42 months in Nova Scotia.

Besides better access to pain facilities, Mailis-Gagnon and her cohorts would like to see provincial and territorial health plans widen the range of treatments available. “Some of the most important treatments for persistent pain fall into the psychological category, such as cognitive behavioural techniques. These are unquestionably not funded by the system, unless you are involved in a car accident or you belong to worker’s compensation.” Universal coverage tends to be limited to medical treatments such as pharmaceuticals.

Pain specialists need to keep their options open. “There are a lot of good pharmaceutical options out there, but they all carry side-effects,” says Morley-Forster. “For some people that precludes them using anything. So…we have to have a lot of tools in our toolbox.”

Those other tools include acupuncture, massage, physiotherapy and lifestyle changes. Morley-Forster adds, “I personally like warm water therapy and cognitive behavioural therapy, to try to get people to think differently about their pain.” The latter approach involves getting a person to recognize and change negative behaviour or thinking patterns through techniques such as imagery, role-playing and systematic desensitization.

Warm water therapy is a natural treatment that is gaining recognition in Canada. Unlike aqua-aerobics classes in regular pools, where the water is cold and the movements can be jarring, warm water helps muscles to become more pliable and therefore more responsive to conditioning exercises, massage therapy or chiropractic treatment.

The gentle resistance provided by the water is ideal for seniors and people recovering from trauma such as motor vehicle accidents. “We want to move people so that they’re building muscle and stability–everything to help balance and co-ordination,” says Judy Doyle, who runs Water Moves Aqua Therapy in Calgary. The medical community has been sending more referrals her way, and she counts among her clients war veterans, who can receive this treatment through Veterans Affairs Canada.

Natural medicine practitioner Dr. Anthony Martin of Sudbury, Ont., favours a non-pharmaceutical approach to pain relief, using food and anti-inflammatory supplements such as systemic oral enzymes (proteins that activate body processes), pine bark extract and hemp seed oil. “The idea, in any treatment, is to reduce inflammation. Systemic oral enzymes (like those found in fruits and vegetables) go into the bloodstream like Pac men (in a video game) and look for inflammation.” Pine bark extract reduces the activity of cooxygenase (COX) enzymes, alleviating inflammation but with no side-effects. Finally, Martin adds, hemp seed oil provides its beneficial effects through a high concentration of the healthy Omega 3 oil. “I found that taking between five and 10 grams a day is one of the great anti-inflammatories you can find.”

But the first thing he tells his patients is to change their diet by eliminating junk food and eating whole foods, particularly fibre, fruits and vegetables. “The key is food. Because of our lifestyles, and especially if you have a chronic disease, what you put in your mouth is going to become either a good experience or a bad experience. You are what you eat.”

Regardless of how you choose to relieve your pain, the important thing is that you don’t wait, says Dr. Lucia Gagliese, a clinical psychologist who conducts research on chronic pain and aging for the University Hospital Network in Toronto. “The thinking out there is, wait until the pain is really bad and then take something. What the research is showing is that it’s the opposite. The sooner you treat the pain, the lower the chances are that it’s going to become chronic.”

As for the age factor, Gagliese says, “You are more likely, as you age, to have some kinds of chronic pain, like arthritis. Other kinds of pain actually decrease as you get older, like some kinds of headaches and visceral pains.” Still other things plateau after age 50, like back pain.

Gagliese emphasizes that while it is not unusual for seniors to have pain, “it is not something that should just be accepted, like wrinkling or losing your hair.” In her studies she has found that older patients tend to be wary of using medication. “They’re reluctant to use it because it can have side-effects, they don’t want to become tolerant, and so on. The evidence, though, is that if you’re careful, if you take your pain medication under a physician’s supervision, it’s very safe. It is much safer in the long run to treat your pain than to experience it for a long time.”

And your mind will be the better for it.

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