Chronic pain, in the absence of any discernible physical cause, is the most common reason for lost workdays in this country, yet doctors remain unsure about what causes the complaint, how to treat it, or even if it exists.
What do you do when the scans, blood tests and exams indicate nothing wrong, but the patient is incapacitated?
"Its a terrible dilemma," said Dr. Kathleen Foley, director of the pain service at Memorial Sloan-Kettering Cancer Center in New York. "Pain is what people say it is. And if you start with the concept that you should believe the patient, then how can you say it is real or unreal, and how do you prove it?"
Frustrated by the skyrocketing number of patients receiving disability payments, most often for lower back complaints, and huge jury awards for "pain and suffering" that no scientist can measure, researchers are striving to understand the genesis of chronic pain and how to treat it.
Many are concluding that chronic pain often results from a cycle of physical and emotional factors that feed on each other: a person with transient pain decides he or she has a pain problem; believing pain is a problem causes a physical response that produces more pain.
Some of the nation's most prominent pain specialists believe that medical and legal practices actually help set the chronic-pain cycle in motion. The barrage of scans and exotic therapies that doctors prescribe for pain convinces healthy people that they have a serious condition.
Prolonged sick leaves and lawsuits that drag on for years allow patients to get out of shape, which only makes pain worse. These doctors criticize the legal system for awarding damages for pain without insisting that claimants be properly treated with physical and psychological therapy. While pain experts recoil at the notion that large numbers of patients are faking pain for profit, they agree that the psyche frequently converts trivial discomfort or a minor injury into a debilitating, lifelong medical condition.
Although a fraction of chronic-pain patients are found to have worn joints or a tendon that is clearly inflamed, the majority have no specific problem that can be found on tests or exams.
"All the evidence suggests that for most people chronic pain is a stress-related disorder, just like ulcers," said Dr. John Loeser, director of the pain clinic at the University of Washington in Seattle. "The difference with pain is that we don't know where to put the tube to look."
Although there are no overall statistics about chronic pain, scientists have compiled extensive data about the current epidemic of lower back pain, the most common type of chronic pain that leads to disability. In recent years, more than 2 percent of all adults reported being unable to work because of this condition, and the cost of their health care plus the compensation they received totaled well over $50 billion annually.
Five percent of all visits to doctors are now for back pain, said Dr. Loeser. "And the numbers keep going up and up and up."
The United States has many more people disabled by lower back pain than any other nation in the world, Dr. Loeser said, and surveys of old medical records show that chronic back pain was a rare diagnosis before World War II.
Recent studies have failed to link chronic pain to physical injury or X-ray findings, but they have found that it correlates with such factors as job satisfaction, depression and the resolution of lawsuits.
Lacking a good understanding of what causes chronic pain or a good yardstick to measure it, doctors, lawyers and juries are forced to make largely arbitrary decisions about which patient will benefit from an injection of anesthetic into the spine, which claimants deserve large jury awards and which employees should be granted disability payments.
"The disability system asks doctors to certify that someone has too much pain to work, but we have no mystical power to determine that," Dr. Loeser said. "You can't take an X-ray and see pain; you can't see it on a biopsy. All you have is a patient's statement that he hurts. Judgments are made, but I don't know if they are right or wrong. I do know that they are not based on medical science."
Neurologists say that they are being called upon to resolve a barrage of legal disputes but that litigation frequently clouds diagnosis and interferes with medical care.
In a study published recently in The American Journal of Pain Management, Dr. Michael Weintraub examined 210 people with chronic pain who were involved in litigation. He found evidence that 63 percent of the patients had pain that was emotional rather than physical in origin. For example, a person with lower back pain might describe a leg going numb, even though all the nerves that leave the spine in the lower back supply only a small portion of the leg.
Chronic pain is a term used to cover a wide variety of conditions, including headaches, back pain, repetitive stress disorder of the hands and jaw pain.