Why Does Pain Hurt?
Our bodies are wonderful machines. I have always been amazed that such a complex organism develops and grows with as few glitches as our body does. One just has to consider that in nine months a human fetus goes from a single cell to a fully developed organism that can breathe, think, see, digest and even control its own temperature. Within the same nine months, we grow a brain that holds ten billion cells, each one linking up to 100,000 other cells. The mechanism that allows an individual nerve fiber to find its way around that maze is one of the best-guarded secrets in nature.
Complexity engenders fragility, and the human body is no exception. Like other animals, we have developed sophisticated systems to protect us and allow our species to survive in a world full of poisons, bacteria and falling rocks. Pain is among the most important evolutionary defense mechanisms. For example, children born with congenital insensitivity to pain, a rare neurological disorder that abolishes one's ability to feel pain, inadvertently and painlessly bite their nails all the way to the bone, and they sometimes die from treatable conditions, such as appendicitis, because there are no symptoms until it is too late. Pain differs from other sensations, such as sight, taste or hearing because the emotions evoked by pain are always negative and aversive, leading to suffering. The reason some people utilize pain to enhance sex is not because it is a pleasurable sensation, but the one most capable of evoking powerful emotions.
Most of us can tolerate severe pain such as childbirth, kidney stones, and migraines, for a short period of time. Few of us, however, can cope with severe unrelenting pain without sinking into a progressive spiral of irritability, depression and despair. When the meaning of pain changes from a fundamental, necessary warning designed to protect the body, to a faulty alarm that continues to scream at the brain even after the danger is long gone, that's when the trouble begins. The problem is made worse by the fact that pain is a personal, subjective experience, which can't be measured any more than a mother's love for her child can, so doctors and other health care professionals may have trouble understanding the magnitude of the affliction, leading to inadequate treatment of chronic pain sufferers.
During the past 25 years the treatment of pain has grown in importance and scope. When once a patient would be told "you just have to learn to live with it" or "it's all in your head," now specialists go to extremes to identify the source of pain, correct it when possible and alleviate it when not. When, previously, medical students would devote perhaps no more than one day to the study of pain, now they have it as an integral part of their curriculum. Pain clinics can be found in most major metropolitan areas in the United States, and many of those clinics have a team composed of specialized physicians, nurses, physical therapists and mental health professionals, whose main job is to treat pain as a disease that affects the body as much as the mind. The pain specialists work is often made more difficult by patients who refuse to accept that pain, like many other chronic illnesses, can and does impair brain function, leading to personality changes, depression and irritability, just to cite a few. Both depression and chronic pain still carry the stigma that somehow the patient is weak and at fault for being unable to "cope" with either one.
Not too long ago scientists believed pain was just another type of sensation. Today we know that we become conscious of the sensation of pain only after the spinal cord analyzes and processes the incoming input from the nerves, and after the brain evaluates the information and transforms that input by adding its own share of previous experiences, cultural biases, and genetic make-up. The nervous system effectively filters how much pain will reach consciousness. For example, we are all familiar with the occasional bruise we get in the trunk or limb, without any recollection of the probable painful accident that must have caused it. During battle, soldiers have been known to ignore serious wounds, only to find out later that they have been hurt. On the other side of that spectrum, scientist have known for a long time that depression, anxiety and stress can cause this pain blocking system to fail, causing pain to "hurt" even more. This so-called pain modulation may be used constructively by patients suffering from chronic pain: music, praying, massage, yoga, electrical stimulation, heat, are all common methods that may help block pain.
When simple pain relief methods don't suffice, medical care is often needed. The first step in managing chronic pain is to come up with the proper diagnosis. Due to the intrinsic subjective nature of pain there's no way to measure it, and many times the cause of pain remains hidden and inaccessible to detection devices such as MRIs, scans, and blood tests. That doesn't mean that the pain is not "real," nor does it indicate that some horrible disease is lurking in the background, waiting to be found, like so many pain sufferers believe. Doctors in medical school are extensively trained to treat known diseases but are ill prepared to deal with pain for which no clear cause exists. This leads to potential conflicts between patients and their physicians, both frustrated from the lack of a "label" for the pain. As important as obtaining a diagnosis, is knowing when to stop looking, beacuse serious physical, psychological and financial damage can result.
By the time a patient reaches a pain specialist, weeks or months may have passed, and several other doctors may have been consulted. As a result, the specialist is often confronted with difficult, frustrating cases, and patients who are emotionally debilitated from that merry-go-round. Some of the most common problems facing the pain physician are:
- Chronic neck and back pain
Low back and neck pain are the most common type of painful ailment affecting adults of any age. It strikes millions of Americans and costs billions of dollars in medical care and lost productivity. Only a minority of people will have demonstrable cause for the pain, and most will improve with time and good sense. However, when pain is persistent and interferes substantially with daily activities more aggressive care is warranted. Many tools are available to the physician treating this type of pain: anti-inflammatories, pain pills, nerve blocks, braces, surgeries, and several more. One of the best, and often neglected, forms of treatment is through the use of exercises that increase strength, flexibility and stamina. A patient's search for instant relief gets in the way of a methodical program that may provide long term benefit. Rarely does a person suffering from spine pain observe maximum improvement without the aid of exercises, with or without other modalities of physical therapy.
We have a much better understanding of headaches than we had just a decade ago. The delineation of which headaches are migraines and which are tension headaches or sinus headaches is much clearer, and therefore, new treatments for them have evolved. The development of a new, very effective class of drugs called triptans has dramatically improved the therapy for migraines, and it has also allowed us to realize that many, if not most, of the headaches we used to call tension and sinus are actually migraines. Today we define a migraine as any headache that is accompanied by nausea and light sensitivity, until proven otherwise. Often times a therapeutic trial with one of the triptan drugs will clarify the type of headache we are dealing with.
Women are affected by migraines three times as often as men, but men are more likely to develop a rather vicious type of headache called "cluster headaches," named for their tendency to strike several times a day for weeks or months, disappearing completely afterwards for variable periods of time.
Analgesic rebound headache is a fairly common type of headache that is due, in part, to the overuse of analgesics. It generally affects a person who suffers from occasional migraines and who, for one reason or another, progressively increases the use of over the counter or prescription medications for a period of months or years, to the point they end up developing a headache as soon as the medication wears off. The only treatment consists in reduction and discontinuation of the offending medications, often with dramatic improvement. The lesson for headache sufferers is that one has to be careful with analgesics and sedatives, and to use medications as prescribed, avoiding excessive self-medication.
Few pains can match the severity of painful neuropathies, or so-called nerve pain. The typical example is trigeminal neuralgia, or tic doloreux, a severe lightning, lancinating pain that affects the face for a few seconds at a time, but repeats itself many times during the day. Other examples include shingles, diabetic neuropath, and carpal tunnel. Nerve pain usually has a burning, shooting, electrical character that is very disturbing to the sufferer and rapidly leads to irritability, insomnia and depression. Furthermore, nerve pain tends to create a "memory" for the pain by changing the chemistry and connections of the nervous system. That means that the pain may persist long after the initial injury is gone. This is often seen in people who undergo an amputation and develop pain in the limb that does not exist anymore, a condition named phantom limb pain.
Around 60 percent of people suffering from a malignancy will develop substantial pain during the course of their disease. Some types of malignancy, such as cancer of the pancreas, are more painful than others. The treatment of cancer pain poses some unique challenges since the disease can be fatal, and the physician must balance pain relief, sedation and side effects such as nausea and constipation, common with the use of strong analgesics. The main goal of the pain specialist when dealing with cancer is to provide the best relief, while allowing the patient to remain alert and functional. When the dose of narcotic analgesics necessary to control pain is so high that the patient can't function in his activities, the doctor may choose to administer the narcotic directly into the spine by means of an implantable pump, which delivers the medication automatically. It allows for a much lower dose of medication and, consequently, fewer side effects.
Arthritis comes in many forms. The most common, and the one most of us will eventually develop, is osteoarthritis. More than a disease, this can be seen as a natural aging of the joints that causes pain and stiffness, and is usually treated with anti-inflammatory medications. More serious types of arthritis include the rheumatoid type, which gradually destroys an inflamed joint. Until recently only palliative treatments were available, such as cortisone orally or by joint injections. Today we have new medications, the so-called "disease modifying agents", that, although unable to cure the disease, may delay the progression of rheumatoid arthritis.
Often misdiagnosed and frequently shunned, patients with fibromyalgia are mostly young women, who suffer not only from generalized muscle and soft tissue pain, but are also plagued by fatigue, sleep disturbances, with memory and concentration difficulties. Because there is no test that can show whether the person has fibromyalgia, it all comes down to the doctor making a clinical diagnosis. Other diseases that cause the same constellation of symptoms have to be excluded before a diagnosis of fibromyalgia can be made, including lupus, depression and low thyroid, among others.
Scientists suspect that true fibromyalgia may be due to a central nervous system problem, as opposed to a muscle disease. The best evidence for this comes from the fact that some viral diseases that affect the brain, such as mononucleosis, can lead to long-term symptoms identical to fibromyalgia, and the same can happen to patients suffering from Lyme's disease, a bacterial infection transmitted by a tick.
- Sleep and Mood Disturbances
Pain specialists know it is very difficult to treat pain if the person has sleep of poor quality. The patient who complains of insomnia needs to be diagnosed and treated as part of pain management. Some patients, however, might not be aware that they have a sleep problem. They may suffer from sleep apnea, a condition that causes decreased breathing during sleep for periods ranging in general from 30-60 seconds, which may occur dozens of times during a night, effectively decreasing the quality of sleep and leading to excessive daytime sleepiness and increased pain. Other sleep problems include restless leg syndrome, the inability to keep the legs still while trying to go to sleep, and nocturnal myoclonus, a jumping of the limbs that occurs during the night, mostly unknown to the person, but quite noticeable to their bed partners, who may get kicked repeatedly during the night.
Depression and anxiety are other major contributors to the suffering caused by pain. We may think about them as amplifiers that don't cause pain but increase its intensity. Since pain often leads to depression, patients may develop a vicious cycle of pain-depression-pain that must be interrupted before adequate results are seen.
© Dr. Moacir Schnapp and Dr. Kit Mays