#phantom limb

The exact cause of phantom limb sensations is unknown. Some believe it results from the brain's attempts to reorganize the nerve impulses it receives from the portion of the limb that remains or from the area near where the removed body part was located. American neurologist and physician Silas Weir Mitchell (1821–1914) first used the term phantom limb in 1872, but the condition was described by Ambroise Paré (c. 1510–1590) as early as 1552. Pare was a French barber surgeon who theorized that central pain memory might be the cause for the sensations experienced by those who lost a limb.

Studies using magnetic resonance imaging (MRI) and positron emission tomography (PET) imaging have demonstrated that a person experiencing phantom limbs and phantom pain has activity in the portions of the brain that are connected by nerves to the part of the body that is no longer there. These studies have led researchers to theorize that the spinal cord and brain are the source of the phantom sensations.

Some researchers have noted instances in which certain areas of the brain are connected to parts of the body that may not be in close proximity to each other. For example, the areas of the brain responsible for reacting to nerve signals from the cheek and the hand are near each other. These researchers suggest that phantom sensations may result from the brain’s attempts to process nerve signals that are getting crossed as the body adjusts to the amputation. In this scenario, a touch to the cheek could be inadvertently cross-wired while en route to the brain and be interpreted as a touch to the hand that has been amputated.

Other theories to explain phantom pain include damage to the nerve endings during the removal of the body part, pressure from scar tissue formed as a result of the amputation, and memory of pre-amputation pain in the affected portion of the body.

Some people appear more likely to experience phantom limbs and phantom pain. These include people who had pain in the limb before the removal, people who also have pain in the remaining part of the limb, and people whose artificial limbs do not fit properly. Other factors that can affect how often or how severely people feel phantom sensations from a missing body part include fatigue, excessive pressure on the remaining body part, stress, infection, and weather changes.

At least half of all people who have a body part removed report at least some phantom limb sensations. However, researchers believe that fear of being diagnosed with a mental condition restrains some people from reporting feeling or pain in a limb or body part that no longer exists. They believe that perhaps 80 percent or more of people who have lost a body part experience phantom limb sensations.

Treatment

While phantom limb and phantom pain sensations are fairly common, they generally do not last long. Early treatment can help lessen the duration and severity of symptoms, so it is important for patients to report the condition to a physician as soon as possible. Many cases can be treated with at-home remedies such as over-the-counter pain relievers and keeping the remaining part of the limb warm. Relaxing activities such as listening to music, reading, or crafting can help by providing a distraction from the discomfort. Moving the affected area can help as well.

For conditions that require medical intervention, a physician may prescribe a variety of medications to help, such as antidepressants, prescription pain relievers, anticonvulsants, antipsychotics, and muscle relaxers. In some cases, treatments that counter the nerve sensations with electrical nerve stimulation may be used, such as transcutaneous electrical nerve stimulation (TENS) therapy, which sends very small electrical signals through the skin and is used for the relief of a number of different types of pain. Some cases may require the use of magnetic pulses sent through the hair and scalp to the brain—transcranial magnetic stimulation—or spinal cord stimulation, which uses an implanted electrode to send small electrical currents directly to the spine.

Hypnosis, biofeedback, acupuncture, massage, meditation, and exercise also can bring relief. Some cases require surgical intervention—a procedure known as regional sympathectomy—to cut the nerves that deliver the pain signals to the spine.