Chronic Pain

by Food and Drug Administration (FDA)

(Page 3 of 3)

"PCA matches the patients' relief to their pain," says Balestrieri. "It also relieves patients of the worry over their pain relief in the majority of cases."

It also helps patients deal with the side effects opiates can cause, says FDA's Wright.

"A substantial portion of patients don't want complete pain relief," says Wright. "They want as much pain relief as they can get without bad side effects."

Wright says that when the first studies were done on the effectiveness of PCA, "we thought that the pain scores [the patients gave] would be zero." (Patients generally rated pain on a four-point scale with four being the greatest amount of pain and zero, no pain.)

"What we found was that patients didn't titrate down to zero, but instead brought the pain down to one or two," he says.

The undesirable side effects of narcotics can be avoided completely with another form of continuous administration — epidural therapy. Epidurals, which inject the narcotics into the membrane surrounding the spinal cord, have been used for many years to block the pain of labor. Now this is being adapted to control pain after some major surgery, especially abdominal.

Drugs injected into the epidural space don't travel to the brain like other types of injections, explains Sherry Fisher, R.N., pain management coordinator at Fairfax Hospital. Therefore, complications such as nausea and respiratory depression don't occur.

With epidurals "patients can talk to me, take deep breaths, cough, and even be up and walking around, sometimes 24 hours after surgery," says Fisher. Normally, after the type of major surgery that requires the kind of pain control epidural therapy provides, "the patient would still be on a ventilator after 24 hours," she says.

However, epidurals aren't effective for every type of pain. Besides pain from abdominal surgeries, epidurals are best used for pain following major chest and urologic surgery, according to Fisher.

No matter what the form of administration, "I don't think people should be exposed to any more pain than they're willing to tolerate," says Dubner.

Chronic Pain

Unfortunately, "when it comes to chronic pain, there are situations where pain cannot be controlled as well with the approaches that are available to us today," says Dubner.

Opiate drugs are usually avoided in chronic pain management because of the potential for tolerance.

Some types of chronic pain that are difficult to control include:

• pain from nerve damage caused by diabetes or shingles
• lower back pain that continues long after the initial injury has healed
• arthritis
• migraine and other chronic headaches.

There is some hope though. Tricyclic antidepressants, especially amitriptyline, have been found to relieve pain in patients with nerve damage. These drugs aid the body's own defenses by trapping serotonin, a pain-blocking chemical, at its point of production in the nerve endings in the dorsal horn of the spinal cord (see accompanying diagram). An excess of serotonin builds up and suppresses pain signals longer than usual.

Although FDA has not approved tricyclic antidepressants for pain control, these drugs are gaining wide acceptance for this purpose. (The practice of medicine may include the prescribing of approved drugs for unapproved uses supported by research and not otherwise contraindicated.)

Treatment of chronic and migraine headache pain may include two drugs approved for heart problems — calcium channel blockers and beta blockers.

Treatment for mild arthritis pain, on the other hand, often begins with aspirin. If the patient can't tolerate aspirin, ibuprofen is a reasonable substitute, says Love. She warns, however, that even though people can buy aspirin and ibuprofen without a prescription, the doses required to treat arthritis pain are too high to be taken without a physician's care.

"The treatment of chronic arthritis, regardless of severity, requires an adequate diagnosis and possible use of many different types of medications, physical therapy, or surgery," says Love.

Tens

Another potential source of relief for chronic pain is transcutaneous electrical nerve stimulation (TENS). Through the use of the TENS device — a battery-powered generator that could be mistaken for a Walkman portable radio or a beeper — electrical impulses are transmitted to the site of pain through electrodes placed on the skin.

With the most common course of treatment, the physician or physical therapist sets the TENS device to deliver 80 to 100 impulses a second for 45 minutes, three times a day.

But there are a wide variety of parameter ranges, and what works for one person may have no effect on another. Determining the most effective settings "is a real art," says Stephen M. Hinckley, a physiologist with FDA's Center for Devices and Radiological Health.

Pain can be very subjective, explains Hinckley. Two people whose pain is caused by the same problem may need very different settings to achieve relief.

If a patient doesn't require hospital care, the patient can use the TENS device, preset to the proper level, at home. The device does not interfere with most normal activities.

A study published in the New England Journal of Medicine in June 1990 questioned the effectiveness of TENS. The study concluded "that for patients with chronic low back pain, treatment with TENS is no more effective than treatment with a placebo, and TENS adds no apparent benefit to that of exercise alone."

But, because a number of previous studies support the use of TENS, FDA still considers TENS to be effective for pain relief for some people.

Although it isn't clear why TENS works, there are two plausible theories, according to the Harvard Medical School Health Letter. The first holds that nerves can easily carry only one message at a time. The electrical pulses from TENS overload the nerves, and the pain message shuts down. A second theory hypothesizes that the electrical pulses stimulate the body to release its own painkilling molecules, called endorphins, into the fluid bathing the spinal cord.

Pain researchers are studying how to stimulate production of the brain's own opiates, such as endorphins, enkephalins and dynorphins, since they may act as natural painkillers, according to NIH's Dubner.

"There are clear indications that stimulation in certain parts of the brain can be helpful in some patients," he says.

Focus on Life

Sometimes, though, none of these therapies will completely relieve the pain for chronic sufferers. They don't have to give up hope, though. For many in chronic pain, behavior modification techniques such as biofeedback, meditation and relaxation training may offer some relief. These treatment approaches are designed to alter a patient's reactions and behavior in response to pain.

"They learn that they can deal with their pain effectively if they focus on improving their quality of life instead of focusing on their pain," says Dubner.

Seymour Rubin, 67, who has suffered with chronic back pain for 40 years, agrees. "If I focus on the pain, it just gets worse," he says. Instead, Rubin keeps busy with walking, reading, and running errands with his wife.

"Singing helps, talking helps," adds Rubin. "And I've just learned to accept the fact that I have pain."

How You Know That You Stubbed Your Toe

1. Nociceptors are specialized nerve endings in the skin and other peripheral tissues that respond exclusively to tissue-damaging stimuli. Prostaglandins sensitize these nerve endings, and the pain message starts on its way to the brain. Aspirin and ibuprofen and, to a lesser extent, acetaminophen can block prostaglandin production at this point.

2. Pain travels along special nerve fibers to the part of the spinal cord called the dorsal horn.

3. Tricyclic antidepressants work here by enhancing the effects of the body's own natural painkillers.

4. From the dorsal horn, the pain ascends to the thalamus and then to the cerebral cortex. Opiates cause the brain to suppress pain messages before they leave the dorsal horn.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.