Phantom limb pain is a sensation that feels like it originates from an amputated body part. Doctors once believed this post-amputation phenomenon was psychological; however, experts now know these are very real sensations. Although the limb or body part is gone, the nerve endings at the site of the amputation continue to send pain signals.
While some patients experience severe, debilitating phantom limb pain sensations, some amputees experience non-painful phantom sensations. Amputees may feel as if they are gesturing or trying to pick something up, in addition to feeling tingling, numbness, hot, or cold sensations.
Usually, phantom limb pain decreases and disappears over time for most people. For others, pain management of phantom limb pain can be challenging, requiring help from a pain specialist.
What Causes Phantom Limb Pain?
Pain is a normal part of the healing process that generally subsides as the body repairs itself. However, it’s not that simple if you are recovering from an amputation. After an amputation, the nerves ending at the site of the amputation continue to function. These remaining nerves make the brain think the entire limb remains attached to the body. Approximately 80% of amputees experience phantom limb sensations in the weeks following an amputation, and 60% of amputees report phantom pain sensations a year after surgery.
The exact cause of phantom pain is unclear. However, the pain appears to originate in the spinal cord and brain. During episodes of phantom limb pain, imaging scans of the brain show activity in the portions of the brain that were neurologically connected to the nerves of the amputated limb. Researchers believe areas of the spinal cord and brain that lose input from the missing limb after an amputation adjust to the detachment in unpredictable ways. These mixed signals result in the brain interpreting the signals as pain, which is the body’s most basic message that something is not right. Sometimes, the brain’s memory of pain is retained and interprets any signal it receives as pain, regardless of signals from injured nerves.
Other studies found that after an amputation the brain seems to remap the missing part of the body’s neural circuitry to another part of the body. Since the amputated area is no longer able to receive sensory information, that information is sent elsewhere in the body. Sensations from a missing hand may instead go to a still-present cheek, for example. When the cheek is touched, the person may sense that an amputated body member, such as a hand, is also being touched. The resulting confusion of senses can result in pain.
Some other factors may also contribute to phantom limb pain, including damaged nerve endings, and scar tissue at the site of an amputation. It is also possible the phantom pain may mimic pain present in the limb before the amputation.
What are the Symptoms of Phantom Limb Pain?
Phantom limb pain has a wide variety of symptoms ranging from tingling and itching to burning and aching. Any sensation a limb might experience before amputation may become a phantom pain. Some patients report feeling as if their missing limb is in a distorted and painful position.
Characteristics of phantom limb pain include:
An onset of pain within a few days of amputation.
The pain may be intermittent or continuous.
The pain most often affects the part of the limb farthest from the body, such as the foot or toes of an amputated leg.
The sensation can be shooting, stabbing, boring, squeezing, throbbing or burning.
Sometimes the phantom pain may feel as if the missing limb is being forced into an uncomfortable position.
The pain may occur with pressure on a remaining portion of the limb.
The pain can become worse by stress, anxiety, and even weather changes.
The patient may experience “telescoping,” the feeling of the missing limb still being part of the body, but it has shrunk to a tiny size, similar to a collapsed telescope.
It’s difficult to identify the frequency of phantom limb pain because patients are usually reluctant to report it. The troubling part of phantom limb pain is that the pain is very real, but patients can clearly see the limb is gone. Therefore, some phantom pain patients may worry their physician might doubt their sanity.
How is Phantom Limb Pain Diagnosed?
There is no medical test to diagnose phantom limb pain. However, doctors identify the condition from the patient’s symptoms and circumstances, such as trauma or surgery, prior to the onset of the pain.
How is Phantom Limb Pain Treated?
Successful treatment of phantom limb pain is challenging. Up until the early 1990s, treatment for phantom limb pain was an additional amputation. By shortening the stump and nerves, doctors thought they could reduce or eliminate phantom limb pain following the initial surgery.
Today, pain doctors base treatment for phantom limb pain on the patient’s level of pain. A combination of multiple treatments may be helpful for some patients. Treatment usually begins with medications, in conjunction with noninvasive therapies. Minimally invasive treatments are also available to help patients. In some cases, surgery may be the last resort to relieve pain.
Next, we discuss specific treatments for phantom limb pain.
Although no medications exist specifically for phantom pain, some drugs designed to treat other conditions have proven helpful in relieving phantom limb pain. Unfortunately, no single drug works for everyone, and not everyone benefits from prescription drugs. Some of the medications used in the treatment of phantom limb pain include:
Antidepressants, drugs that work by modifying the chemical messengers that relay pain signals. Antidepressants may also help with sleep, which can help patients feel better.
Anticonvulsants, drugs that work by quieting damaged nerves to slow or prevent uncontrolled pain signals.
Narcotics may be an option for some people. Taken in appropriate doses under a doctor’s direction, they may help control phantom pain.
N-methyl-d-aspartate (NMDA) receptor antagonists, this class of anesthetics works by binding to the NMDA receptors on the brain’s nerve cells and blocking the activity of glutamate, a protein that plays a significant role in relaying nerve signals.
As with medications, the noninvasive treatment of phantom pain is a matter of trial and observation. The following techniques may relieve phantom pain:
Heat application. Sometimes the application of heat to the area of amputation can ease the pain.
Biofeedback. The process of biofeedback helps a patient become aware of normally involuntary processes inside the body (such as muscle tension, temperature, and heart rate control). Biofeedback helps the patient gain some conscious control of these processes. This awareness of the body helps the patient relax, which can help relieve the pain.
Relaxation techniques. Various methods to help the mind alter its focus to something other than the source of pain.
Massage. Focused rubbing of the amputated area may contribute to relieving the discomfort associated with phantom limb pain. Massage can also help the patient relax, decreasing stress and tension.
Transcutaneous Electrical Nerve Stimulation (TENS) is a device that sends a weak electrical current via adhesive patches on the skin near the area of pain. The stimulation may interrupt or mask pain signals, preventing them from reaching the brain.
Mirror therapy. The patient watches a reflection of the whole limb in a mirror while receiving physical therapy. Seeing the reflection helps the brain to remap neural pathways to register that the ‘virtual’ limb is intact and moves without pain.
Acupuncture.Studies by the National Institutes of Health show 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.
Minimally Invasive Therapies
Injection. Sometimes pain-killing medication, such as local anesthetics and steroids, can provide phantom limb pain relief.
Spinal Cord Stimulation (SCS). A neurostimulator delivers mild electrical impulses to the epidural space near the source of chronic pain impulses. These impulses interfere with the pain signals to the brain. A trial stimulator is typically worn for five to seven days externally. If the trial successfully relieves the pain, the patient may decide to have a permanent SCS placed under the skin.
Nerve Cuff Stimulation. A small electrode is wrapped around nerves traveling to the amputated limb. Instead of blocking nerve signals, the cuff delivers an imperceptible electrical stimulation to the nerve that replaces the sensation of pain with a pleasant signal to the brain. The user manually activates the cuff with a small wireless remote control when pain is felt.
Nerve block. Medications that help interrupt pain messages between the brain and the site of the phantom pain.
Surgery may be an option if other treatments do not help. Surgical options include:
Brain stimulation. Similar to spinal cord stimulation, electrodes deliver a small electrical current within the brain
Stump revision or neurectomy. If the pain is from nerve irritation in the stump, surgery can sometimes be helpful. But, cutting the nerves includes a risk of making the pain worse.
On the Horizon
Researchers now believe there is a way to rewire the brain to help reduce pain from a phantom limb, according to a University of Cambridge study. The technique involves distracting the mind from mixed signals it may receive as a result of losing the limb.
Another new approach to relieving phantom pain includes virtual reality. A computer program, combined with special goggles, mirrors the patient’s intact limb, so it appears there has not been an amputation. The patient can move the virtual limb around to accomplish various tasks, such as batting a ball hanging in midair. Although tested on only a few people, this technique appears to help relieve phantom pain.
What Are the Risk Factors for Phantom Limb Pain?
It’s still unknown why some people develop phantom pain after an amputation while others do not. However, there are several risk factors for the development of phantom limb pain, including pain in the limb before amputation, pain in the stump, the use of a prosthetic limb, and the number of years since the original amputation surgery. The most significant risk factors include amputation of bilateral limbs and lower extremity amputation.
Some factors that may increase the risk of phantom limb pain include:
Pain before amputation. Researchers have found that if pain was present in a limb before amputation, patients are more likely to have pain afterward, especially immediately after amputation. Researchers believe the brain retains a memory of the pain and may continue to send pain signals, even after removal of the limb.
Stump pain. Amputees with persistent stump pain usually have phantom pain, as well. Stump pain can be the result of an abnormal growth on damaged nerve endings (neuroma). These growths on the nerves often cause painful nerve activity.
Ill-fitting artificial limb (prosthesis). A prosthetic device that does not fit properly can be the source of phantom limb pain.
Is it Possible to Prevent Phantom Limb Pain?
If a person experiences pain in a limb scheduled for amputation, there is a greater risk of developing phantom pain after the amputation. Some doctors recommend a regional anesthetic (spinal or epidural) beginning a few days before the scheduled amputation. The anesthetic may help reduce pain immediately following surgery, and reduce the risk of chronic phantom limb pain.
Novus Spine & Pain Center
It is important to immediately discuss any phantom pain with your doctor, because early treatment by an experienced pain management expert can help reduce the chances of the pain developing into a chronic condition.
Novus Spine & Pain Center is in Lakeland, Florida, and specializes in treating phantom limb pain. By using a comprehensive approach and cutting edge therapies, we work together with patients to restore function and regain an active lifestyle, while minimizing the need for opiates.