Phantom pain feels like it's coming from a body part that's no longer there. For decades, doctors believed this post-amputation phenomenon was a psychological problem, but experts now recognize a physical cause for this pain — and that it actually originates in the brain.

Most people who've had a limb removed report that it sometimes feels as if their amputated limb is still there. This painless phenomenon, known as phantom limb sensation, can also occur in people who were born without limbs. Phantom limb sensations may include feelings of cold, warmth, itchiness, or tingling — but should not be confused with phantom pain. Similarly, pain from the remaining stump of an amputated limb is not the same as phantom pain.

For some people, phantom pain gets better over time without treatment.

For others, managing phantom pain can be challenging. You and your doctor can work together to treat phantom pain effectively with medication or other therapies.

Signs and symptoms

•Onset within the first few days of amputation.
• Tendency to come and go rather than be constant.
• Seeming to come from the part of the limb farthest from the body, such as the foot of an amputated leg.
• May be described as shooting, stabbing, boring, squeezing, throbbing, or burning.
• May be triggered by weather changes, pressure on the remaining part of the limb, or emotional stress.

Causes

The exact cause of phantom pain is still unclear, but it appears to originate in the brain. After an amputation, the nerves that used to serve that limb apparently "rewire" themselves, which remaps the brain's circuitry. During imaging scans — such as magnetic resonance imaging (MRI) or positron emission tomography (PET) — specific portions of the brain show activity when the person feels phantom pain.

Risk factors

• Pain before amputation. Some researchers have found that people who had pain in a limb before amputation are likely to have it afterward, especially immediately after amputation. This may be because the brain holds on to the memory of the pain and keeps sending pain signals, even after the limb is removed.
•Stump pain. People who have persistent stump pain usually have phantom pain, too. Stump pain can be caused by a neuroma, an abnormal growth on damaged nerve endings that often results in painful nerve activity.
• Poor-fitting artificial limb (prosthesis). Talk to your doctor to be sure you're putting your artificial limb on correctly and that it fits right. If you think your artificial limb may not fit properly, or is causing pain, talk to your doctor.

Treatment

Finding a treatment to relieve your phantom pain can be difficult. Doctors usually begin with medications and then may add noninvasive therapies, such as acupuncture or transcutaneous electrical nerve stimulation (TENS). More invasive options include injections or implanted devices.

Surgery is done only as a last resort. Treatments on the horizon may use virtual reality goggles or mirror boxes to fool the brain into believing the amputated limb is still under its control.

Medications

• Antidepressants often can relieve the pain caused by damaged nerves. They work by modifying chemical messengers that relay pain signals. Antidepressants also may help you sleep, which can make you feel better.
• Anticonvulsants. Epilepsy drugs are often used to treat nerve pain. They work by quieting damaged nerves to slow or prevent uncontrolled pain signals. Studies have shown mixed results, however, regarding their effectiveness in reducing phantom pain.
• Narcotics may be an option for some people. Taken in appropriate doses under your doctor's direction, they may help control phantom pain. However, you may not be able to take them if you have a history of substance abuse. Even if you don't have a history of substance abuse, these drugs can cause many side effects such as constipation or sedation.

Noninvasive therapies

As with medications, treating phantom pain with noninvasive therapies is a matter of trial and observation. The following techniques may relieve phantom pain:

• Transcutaneous electrical nerve stimulation (TENS). In TENS, a device sends a weak electrical current via adhesive patches on the skin near the area of pain. This may interrupt or mask pain signals, preventing them from reaching your brain. Although safe and painless, TENS doesn't work for everyone with phantom pain.
• Acupuncture. The National Institutes of Health has found that acupuncture can be an effective treatment for some types of chronic pain. In acupuncture, the practitioner inserts extremely fine, sterilized stainless steel needles into the skin at specific points on the body. It is thought that acupuncture stimulates your central nervous system to release the body's natural pain-relieving endorphins.

Invasive therapies

• Injections. Sometimes injecting pain-killing medications — local anesthetics, steroids or both — into the stump can provide relief of phantom limb pain.
• Spinal cord stimulation. Your doctor inserts tiny electrodes along your spinal cord. A small electrical current delivered to the spinal cord can sometimes relive pain.
• Intrathecal delivery system. This procedure allows medication to be delivered directly into the spinal fluid. Much lower doses of medication are needed with this route of delivery. It can be useful for people who experience pain relief with oral medications but experience intolerable
side effects.

Surgery

• Deep brain stimulation. Deep brain stimulation, also known as motor cortex stimulation, is similar to spinal cord stimulation except that the current is delivered within the brain. A surgeon uses a magnetic resonance imaging (MRI) scan to position the electrodes correctly. Although the data are still limited, deep brain stimulation appears to be a fairly promising option in selected individuals.
• Stump revision or neurectomy. If phantom pain is triggered by nerve irritation in the stump, surgical resection or revision can sometimes be helpful. But cutting nerves also carries the risk of making the pain worse.

Newer approaches to relieving phantom pain may involve fooling the brain into thinking it can still control the amputated limb.

Myoelectric prosthesis. This type of artificial limb has motors controlled by electrical signals that occur during voluntary muscle activation in the remaining limb. Intensive use of a myoelectric prosthesis sometimes results in reduced phantom pain.

Mirror box. This device contains mirrors that make it look like an amputated limb exists. The mirror box has two openings — one for the intact limb and one for the stump. The person then performs symmetrical exercises, while imagining that the missing limb is moving.

This helps relieve phantom pain in some people.

Virtual reality goggles. The computer program for these goggles mirrors the person's intact limb, so it looks like there's been no amputation. The person then moves his or her virtual limb around to accomplish various tasks, such as batting away a ball hanging in midair. Although this technique has been tested on only a few people, it appears to help relieve phantom pain.

Prevention

Because the risk of developing phantom pain is higher for people who have experienced pain in the limb before amputation, some doctors numb the limb for several days before the amputation surgery. However, this practice hasn't been consistently effective in preventing phantom pain.

(Dr. Gary S. Sy, M.D. is the medical director of Life Extension Medical Center located at The Garden Plaza Hotel (formerly Swiss Inn Hotel) 1370 Gen. Luna St., Paco, Manila. He is a Diplomate in gerontology and geriatrics, advocate diet-nutritional therapy, and conducts free seminar every Friday about Age-Related Health Problems. E-mail Address: lifeextension_drgarysy@yahoo.com)