Unlocking Pain's Secrets

(9 of 10)

which electronic devices are used to teach patients to relieve tension, has proved helpful for a number of ailments, including one of the most perplexing problems in medicine: phantom limb pain, the often agonizing sensations that amputees "feel" in missing limbs. Psychophysiologist Richard Sherman, of Dwight David Eisenhower Army Medical Center in Fort Gordon, Ga., has found that the pain, which afflicts about 80% of amputees at one time or another, is sometimes due to muscle spasms in the stump. When Sherman teaches patients to relax the affected muscles through biofeedback training, the sensations in the phantom limb usually disappear.

For cancer patients, more drastic measures are often needed. According to Kathleen Foley, chief of the pain service at Sloan-Kettering, only about one-third of cancer patients suffer severe pain. With these, the tumor is the cause in 65% of patients, either because it impinges on nerves or because it releases chemicals that affect the nervous system. An additional 30% have pain resulting from the treatment (for example, chemotherapy). Cancer of the pancreas and of bones can be particularly painful because of the sensitive nerves in or near these organs. In the vast majority of cases, cancer pain can be alleviated with drug therapy, including narcotics like morphine or methadone. These may be administered by mouth, by injection into the muscle or directly into the spine via surgically implanted catheters. An implantable morphine pump that provides a continuous infusion of the drug is being tested for use by cancer patients. Unfortunately, patients may develop tolerance to narcotics, and their doctors often fail to provide high enough doses to keep pain at bay.

Surgery is the last recourse of the pain patient. "I spend an awful lot of my time telling people not to have it," says Neurosurgeon Poletti of Massachusetts General Hospital. Although operations to destroy nerves can provide immediate relief, the benefits rarely last more than six months to a year and may be followed by intense, burning pain that is worse than the original complaint. Surgery is often reserved for terminal-cancer patients. For such patients, neurosurgeons have devised delicate operations to cut nerves causing local pain, and even to sever nerve tracts in the spinal cord and brain. In some instances, rather than destroy nerve tissue, doctors can implant electrodes into the spinal cord or brain. The patient can then use an external transmitter to stimulate nerves directly when he feels pain.

Surgery may also be appropriate in cases of the severe facial pain known as trigeminal neuralgia, or tic douloureux. For 16 years, Dr. Mat Boname, 81, of Oxford, N.Y., suffered this excruciating pain, despite the efforts of five doctors. Finally, a delicate operation in which electrically induced heat was used to destroy a facial nerve brought relief. The effect was immediate, he says: "When I came up from the operating room, I had no pain at all."

As the understanding of the pain pathways improves, researchers have great hopes of discovering better methods of analgesia. The search is on for a narcotic that works on the body's opiate receptors without provoking the side effects of morphine. Meptazinol, a drug developed in Britain by Wyeth Laboratories, may be a good candidate. "I think this could be the first in a new