Wednesday, January 12, 2011

Chronic pain: The enemy within

Mary Vargas spent her last pain-free moments driving down a country road to visit a Connecticut flower farm. She was 23 and newly married, a law student about to start a summer job. It was the day after Independence Day, 1996.
It also was the day her independence from doctors and hospitals would end. Vargas stopped to make a left into the parking lot. A driver who was admiring the scenery plowed into the rear of her car. Vargas' head whipped back and forth like a ball on a spring, damaging her spine. The injury transformed her into one of millions of Americans tormented by chronic pain.
"My husband describes pain as almost being a third person in our marriage," she says.
As many as 40 million people may share Vargas' plight. A new USA TODAY/ABC News/Stanford University Medical Center poll indicates that 19% of American adults — almost 1 in 5 — say they suffer from chronic pain; 44% have acute, or short-term, pain. Half of the 1,204 respondents cite the source of their discomfort as a medical injury or condition such as joint pain, heart disease or cancer. (The poll's margin of error is plus or minus 3 percentage points.)
"The problem is absolutely enormous," says Russell Portenoy, chairman of pain medicine at New York's Beth Israel Medical Center. "It rivals every serious public-health issue, whether you're talking about heart disease, cancer, obesity or anything else."
Still, the burden of pain will grow as the population ages. More than half of patients reporting chronic pain were older than 55.
A study of pain's effect on worker productivity reported in The Journal of the American Medical Association in November 2003 calculated the cost in the USA at more than $62 billion a year from reduced performance alone. Add in the cost of treatment and lost workdays and the total climbs to an estimated $100 billion, according to the American Pain Foundation.
The psychological effects of pain amplify the trauma, contributing to depression, anxiety, sleeplessness and suicide. "Many people in severe pain from terminal illness fear their pain more than they fear death," says Scott Fishman, chief of pain medicine at the University of California-Davis.
Despite the burden that pain imposes on society, pain relief has long been a stepchild of medicine. Many pain medications derive from aspirin and opium, whose origins date back 2,000 years.
Pain medicine isn't recognized by the American Board of Medical Specialties as a primary medical specialty on par with cardiology, oncology or anesthesiology.
The American Board of Pain Medicine has taken the lead in educating and credentialing pain medicine specialists. So far, the board has certified just 1,700 doctors as pain specialists. That's about one pain specialist for every 23,500 people who need care.
With specialists so rare, many pain patients are cared for by doctors who lack training and experience in the appropriate use of a range of pain therapies, among them drugs, spine stimulators and implanted pumps, and alternative therapies, including acupuncture.
From doctor to doctor
Patients hopscotch from doctor to doctor for years before they're given an accurate diagnosis, pain specialists say, and it may take even longer to find appropriate care.
"I always ask my incoming patients, 'How many physicians have you gone to with this complaint?' " says B. Todd Sitzman, medical director of the Center for Pain Medicine in Hattiesburg, Miss. "It's unusual to see someone who hasn't gone to at least three other physicians looking for answers."
The upshot, doctors say, is that patients suffer. The survey bears this out. Of those surveyed who sought care, 90% reported that the doctor understood their pain problem well, but just 30% reported getting a "great deal" of relief.
Vargas, of Emmitsburg, Md., now a health discrimination lawyer, suffers from overwhelming pain, possibly because doctors who weren't trained in pain medicine told her to wait six months to see whether her injuries would heal. By then, it was too late. Fishman and other experts say it is critical to intervene immediately and break the pain cycle before the nervous system loses its ability to turn the pain off.
After a year of waiting, Vargas began an agonizing odyssey from doctor to doctor, hospital to hospital. Finally, one of her three physical therapists referred her to a pain specialist. He recommended that she allow surgeons to implant a spinal cord stimulator, an electrical device that sends a signal to electrodes at a point above the damaged nerve and interferes with transmission of the pain signal.
"I was on a number of medications, but after we got the stimulator working, I was able to drop all but one," says Vargas, who still takes a narcotic called fentanyl. "I was able to have a baby and do all kinds of things I couldn't imagine doing without the stimulator." The couple's son, William, is 2½ .
"The pain of childbirth has a beginning and an end and a positive result. With chronic pain, there is no end," Vargas says.
The science of pain
The more researchers delve into the nature of pain, the more they realize how complex the pain network is. "There's more to pain than we ever dreamed of," Fishman says. "Whenever we think we've found an answer to the puzzle, we realize there are more questions."
In someone with a healthy nervous system, pain can be a lifesaver — a sentinel on duty to warn of potential risks and prompt protective responses.
Gabrielle "Gabby" Gingras, 4, of Elk River, Minn., illustrates how important pain can be.
The playful little girl is one of very few children in the world with a genetic defect called congenital insensitivity to pain. She lacks the nerves to warn her that the knife is sharp or the glowing coil on the stove is burning her hand.
The first inkling of this came the day after Gabby was born, when a nurse pricked her heel for a blood test and she slept through it. Then, when she began teething, she chewed her tongue and knuckles to a pulp. Rubbing her eyes has left her blind in one and with 20/300 vision in the other. When she broke her jaw, which had been weakened by an infection, it took a month for her parents to realize it.
"We're trying to teach her to blink her eyes and bend her knees when she jumps," says her dad, Steve, 40. "We're trying to teach her to tell when water's too hot."
People with congenital insensitivity to pain often don't survive past middle age, doctors say. They are often crippled, their lives cut short by injuries and infections.
Gabby's mom, Trisha, 39, says she finds herself envying mothers of children with cancer. "If they go five years and beat it, they're done. With Gabby, it's never going away."
The couple, who also have a healthy daughter named Katie, created a foundation to be a networking tool for families whose children have similar conditions. Its name: "The Gift of Pain."
The pain-sensing nerves that Gabby lacks are the tiniest and most vulnerable, because they have the least insulation. The nerve endings are called nociceptors. The highest concentrations are in the areas needed for survival, especially the head, mouth, hands and feet. When they encounter a stimulus, such as a pinprick, they send a message through trunk cables to a part of the spinal cord called the dorsal horn. This is the switchboard that relays pain signals to the brain. It uses a second nerve network to relay everyday sensations.
If you prick your finger on a rosebush, nerves carry signals to the brain, the brain pinpoints the location of the injury and sounds an alarm to pull back to prevent further damage. It sensitizes a wide area around the injury to expand the perimeter of protection. And it signals the body's pharmacy to produce its own potent natural painkillers called endorphins.
These chemicals, produced in cells throughout the body, act just like morphine and offer temporary relief from pain.
But sometimes the system goes haywire. In some cases, when nerves are injured, the wires for pain and everyday sensations cross. It can occur after an injury or spontaneously. It occurs in shingles, because the virus that causes the illness, varicella, nests in the nerves. Nerves for everyday sensations are co-opted into the pain system, transforming mild sensations, like the brush of a sleeve, into agony.
There is also a mental component to pain because the brain registers pain in the areas that govern emotion, Fishman says. Someone who suffers a serious injury also may feel anxiety, fear and depression, he says.
One of the most remarkable forms of chronic pain is phantom-limb syndrome. Because early humans who lost limbs couldn't survive, the nervous system has never adapted to amputations. It's as if the amputation didn't exist. The brain, it seems, can't accept such an overwhelming loss.
David Borsook of McLean Hospital in Boston is a pioneer in using magnetic resonance imaging to study phantom-limb pain. He says the brain's distortions of the pain experience are almost impossible to grasp. He tells of the time he touched a phantom-pain patient on the mouth, face, foot and stump where his arm used to be. "He was freaked out by it and said he could feel me touching the (back) of his missing hand," Borsook says.
Borsook gave him an injection to block his pain. Then he placed him in a magnetic imager that detects iron molecules in blood. By tracking blood-flow patterns, the device maps activation of regions of the brain. "If I brushed him on the affected side," Borsook says, "the one area that stood out in the imager is the area of the brain where the missing hand is represented."
Borsook and Alyssa Lebel of Children's Hospital in Boston are using the same imaging method in children to study how pain changes the physical architecture of the brain. They report witnessing entirely different brain patterns when they activate normal and abnormal nerves. The study offers a bonus for the injured children who take part. They can see that their pain is real, Lebel says. "I don't just tell them that it's in their head. I show them."
The treatment horizon
Unfortunately, efforts to treat pain have lagged behind the researchers' ability to understand it. To jump-start research, Congress five years ago declared this the Decade of Pain Control and Research. Researchers have made some strides, developing nerve stimulators like the one used by Vargas and implantable pumps that deliver morphine and other painkillers into the spine.
Researchers are making a major push to improve on opiates because they can promote addiction and because some patients must be given escalating doses or the drugs lose their effectiveness. Among the new drugs now on the market is a Lidocaine patch, made by Endo, that has proven effective against the pain from shingles.
A drug called Cymbalta not only combats depression but also eases the pain of nerve damage from poor circulation in diabetes cases. Perhaps the most interesting new painkiller, approved in December, is derived from the fish-killing toxin of the Conus magus snail.
Called Prialt, it is 1,000 times more potent than morphine and is delivered directly into the spine through an implantable pump. But Prialt has drawbacks. It causes severe dizziness and cognitive problems at high doses. Despite its potency, it works in just 50% of those who try it, says the drug's developer, George Miljanich of Elan Pharmaceuticals.
Randy Rubida, 48, of San Jose, Calif., injured his neck when his car was rear-ended by another vehicle. He says Prialt has eased the spasticity in his legs, making it easier for him to walk again. But it hasn't eased his pain much. "The pain is so intense at times I can't tell a difference," he says.
Prialt works by blocking a contact point between nerve cells called a calcium channel. Other drugs do this, too. A seizure medication called Neurontin is regarded as one of the best drugs available for nerve pain, but it isn't readily absorbed at the higher doses some patients might need for effective pain relief. A new anti-seizure drug, Pfizer's Lyrica, appears to be one of the most promising drugs yet for diabetic nerve pain and pain linked to spinal cord injury.
Fishman says medicine still has much soul-searching to do when it comes to treating pain.
"We've wandered away from the basic ethic of medicine that we cure what we can, but we alleviate suffering always. We've got to come back to our roots."
Contributing: Anthony DeBarros and Susan O'Brian