Post-Amputation Pain
Immediate Post-op Pain
Phantom Sensation
Phantom Pain
Residual Limb Pain
Pain Management
Sensory Cortex of the Brain
The sensory nerves
Nerve transmission and neural circuits
Amputation and the sensory nerve circuit
Conclusion
Editors note

Post-amputation pain is one of the most common complaints heard by the staff of the Amputee Coalition of America (ACA), and how to manage the pain is one of the most frequently asked questions.  Ideas about management are one of the frequent topics of conversation at amputee support group meetings and on amputee discussion list services on the Internet.

Why is there so much discussion about post-amputation pain?  Because it is one of the most commonly experienced situations following an amputation. Actually, there are several types of sensations following an amputation that should be discussed when referring to post-amputation pain.  Some of them are extremely painful and terribly unpleasant; some are simply weird or disconcerting.  In one form or another they are experienced by virtually 100% of people following an amputation.  This article will attempt to explain them and differentiate between them so that conversation about them will be meaningful and precise.

Future issues of InMotion will discuss in detail what is known about the cause of pain and its management.  First, however, we need to have a common use group of terms to describe and define the different kinds of pain.

Immediate post-op pain is the pain experienced after any surgical procedure where skin, muscle, bone and nerves are cut.  Essentially everyone experiences some degree of post-op pain following an amputation.  It can usually be controlled with pain medication and subsides fairly rapidly as swelling goes down, tissues begin to heal, and the wound stabilizes. This is simply part of the natural healing process.  It appears from recent research that it is critically important to adequately treat immediate post-op amputation pain because adequate early control decreases the chances of severe problems later.  Surgeons are being encouraged to be much more liberal with pain medication in the immediate post-op period.  Continuous post-op epidural analgesia is being recommended for pain management since it can be very effective.  Adequate doses of narcotic and non-narcotic analgesics (pain medicines) should be prescribed in a fairly rapidly decreasing program to fit the decrease expected in the pain itself.

For amputees who are experiencing an unusually great amount of 
post-op pain or pain in the phantom limb, (which has been removed), early referral to a comprehensive pain management program is extremely important.  Early referral for expert management can remarkably decrease long-term problems with post-amputation pain.  Here, an ounce of early treatment can be worth a pound of late treatment.

Phantom sensation is a term used to mean any type of sensation which the amputee experiences in the portion of the limb that has been removed.  It can include: tingling, warmth, cold, pain, cramping, constriction, and any other imaginable sensation.  Essentially, any sensation that the limb could have experienced prior to the amputation, (and some which it could not), can be experienced in the amputated “phantom” limb.

Virtually all amputees who are old enough to talk have reported phantom sensations of some sort, especially if asked.  Some amputees will not voluntarily mention it since they think that it indicates that their mind is unhinged!  It is actually not crazy thinking at all.  Instead, it simply means the part of the brain, which has always felt that limb, is still reporting some sensations to the rest of the brain.  What the thinking part of the brain knows (that the limb is gone) may be different from what the feeling part of the brain reports (that the nonexistant limb is being squeezed).

Essentially, all amputees who are questioned report that there is phantom sensation present.  Some children born without a limb even report that they can feel the part that they never have had present.  So long as the sensation is not unpleasant, there should be no real problem once the reality of phantom sensation is explained.  It is usually only when the phantom sensation is unpleasant, noxious, painful, that the phantom sensation is a problem that needs specific treatment.

The really difficult part of post-amputation pain to manage is phantom pain.  It is defined as pain in the missing or amputated part of the limb(s) or some part of it.  It is important, from a treatment standpoint, to differentiate between phantom pain and pain in the residual limb (stump).  They are very different problems with totally different causes and very different treatments.  Phantom pain is never experienced in the residual limb (stump) even though it can be triggered by something happening to the residual limb.  Residual limb pain is always experienced in the portion of the limb that is present.

Unfortunately, phantom pain is experienced by 60-70% of new amputees and after a year as many as 40% of them may still be bothered by it in a significant way.  Often it diminishes a lot in its severity over time.  Many amputees report that it becomes much less frequent as time goes along; however, when it recurs it may be just as bothersome as when it was first experienced. 

There is tremendous variability of this phantom pain. It can be extremely unpleasant and even disabling for some amputees.  It is complex, resistant to treatment and very frustrating to amputee and caregivers alike.  It is really this part of post-amputation pain that this series of articles will focus on since it is the most severe part of the problem.

Many amputees experience pain in the part of the limb left 
after the amputation (residual limb, stump).  Immediately after surgery it is expected due to the massive tissue disruption of the surgery itself.  Later, the pain can be due to a number of mechanical factors such as poor prosthetic socket fit, bruising of the limb, a neuroma in an unprotected location, chafing or rubbing of the skin, and numerous other largely mechanical factors.  Pain in the residual limb can be caused by poor circulation and nerve damage from diabetes. 

Since there are numerous problems that can result in pain in the residual limb, it is important to discuss residual limb pain with your surgeon, physician, and/or prosthetist.  Each of them may have valuable input into solving the problem before it becomes more severe.  Further discussion of residual limb pain will also occur in this series of articles.

Unfortunately, even in 1998, our understanding of the way that the brain handles pain and other sensations is still fairly crude.  A lot of guesswork is still involved.  We can observe many things that we do not truly understand.  That makes a reasonable discussion of pain much more difficult.  It also makes devising a rational plan of treatment very difficult.

The problems of management are made much more complex by the differences between amputees.  The teenage girl who has a leg removed at the hip for cancer is very different from the senior with diabetes and an amputation below the knee.  Both of these are very different from the mill operator whose arm is pulled off by a machine.  Still different is a motorcycle rider whose leg is crushed, stabilized, does not heal, and finally requires an amputation.

All of these issues underline the fact that management of pain is a major problem.  This series of articles is not planned to allow you to treat your own problems without professional help.  They are intended to allow you to become an informed consumer who can manage your own care, ask the right questions, insist on adequate management and information, and seek an optimal outcome for yourself.  Perhaps these articles will even help the professionals who are giving care to better understand the scope and severity of the problem.

The authors of this series have not finished writing the articles yet.  They have done tremendous research and will be doing more.  They will contact numerous experts and researchers so that the information will be current and valid.  They will rely upon you, the readers, for feedback to make the articles more useful and meaningful. 

The authors cannot answer each question that comes to InMotion regarding pain;  however, they will try to use those questions to better aim their research and writing.  Often, individual questions will be worked together with other questions to provide a comprehensive answer.

In the last issue of InMotion there was an article introducing our discussion of post-amputation pain. In this current article we will examine the ways in which the pain that we experience is actually “felt” by each of us. In order to understand pain, we need to examine an incredibly complex subject known as neurophysiology. I will try to keep the discussion basic so that it is easy to understand.

You need to know that, despite intense research in this area, there is still very much that is not known or understood about human neurophysiology. We will build from those areas that are understood and try to make some logical guesses about what is not truly known. We will use some comparisons or analogies that may help us think about what is happening but they may not be truly scientifically accurate. The goal is for you to be able to think clearly and ask good questions about this vitally important area of post amputation rehabilitation.

This true statement has probably angered more people than any other. It is scientifically true that we all feel pain by using our brains. If our brain is not working and we are not aware, we do not feel pain. The misunderstanding arises when people think that “in your head” means imaginary.

Pain is actually felt in the sensory cortex of the brain. The sensory cortex receives messages from the rest of the nervous system and organizes them into a pattern that the body can experience, either feeling them, seeing them, tasting them, smelling them or hearing them. The sensory cortex acts much like a television set, which picks up information, organizes it, and then displays it so that it can be understood. Without the television set, the information on the cable or in the air cannot be experienced in any useful way. You can think of the sensory cortex as the television screen.

The sensory part of the brain is far more complex than a simple television set. It is much more like a television studio control booth with many television monitors, each concentrating on the input from a different camera. Only our brain has millions of incoming cameras which we can concentrate on, but not all at once. Our attention can only be concentrated on a few things at one time, much like the television director choosing the view of one camera to send out to our homes.

As a part of the nervous system, the sensory nerves pick up information from their environment. They sense pain, heat, cold, touch, sound, vision and other things. The nerves themselves are very specific. A temperature nerve cannot experience pain. A touch nerve cannot experience sight. These sensory nerves are much like television cameras, microphones, and thermometers. Each provide information based upon what they sense in the environment. The thermometer measures temperature but cannot hear noises, etc. Pain nerves are among the most primitive nerves we have. They experience pain when something harmful or disruptive happens to part of our bodies. They may feel being burned but cannot tell if the burn is from chemicals, heat, cold, or friction. They can feel being cut but cannot tell if it is a knife or a needle. They are not nearly as fast as some nerves, and they cover a fairly wide area so that it may actually be hard to be sure exactly where the pain originates.

The sensory nerves pick up the information from the environment but they must have the sensory cortex to interpret what they sense and they must also have the incredibly complex nervous system to connect them together and transmit the messages. The nervous system is like the connecting cables, television station, transmission towers, cable facilities, and antenna in your television system. Each of the components has its own role to play. If any one of them is abnormal the outcome may be flawed or even absent.

There are many points where bad information can enter the system, just as there are many places where your television image can be messed up. What your sensory cortex actually feels for you is a combination of all the things that happen from the nerve ending in the skin, muscle, bone or other tissue, through all the connecting nerves, all the way to the sensory cortex.

Just as there are many complex circuits between the camera and television screen, there are incredibly complex neuro circuits between the sensory nerve fiber and the sensory cortex. These complex circuits help control what you feel and help you make use of the information that you receive.

Nerves conduct information much like television cables transmit images. It is done by a series of electrical discharges along the nerve fibers. When the sensory nerve is stimulated by something like a pin-prick, the nerve cell becomes excited and sends an electrical message down its long fiber (called an axon) toward the spinal cord. The nerve axon from your toe runs all the way to the spine, where it connects with other nerve fibers. 

When the electrical signal gets to the end of the nerve axon, the impulse is transmitted to the next nerve by release of neurotransmitter substances like acetylcholine. The acetylcholine stimulates the next nerve, which acts like a relay runner and picks up the message can carries it along the spinal nerve tracts toward the brain.

The simple transmission of the nerve messages gets much more complicated in the spinal cord and brain because, there, they are affected by other types of nerves which can either make passage of the messages easier (facilitation) or harder (inhibition). They are also affected by a number of chemicals like narcotics, sedatives, muscle relaxers, anti-seizure drugs, local and general anesthetic agents, and many others. All these chemicals in some way influence nerve transmission. Some of the actions we understand quite well. Some of them we understand poorly. Many affect some people more than others and therefore are somewhat unpredictable from one person to the next.

Unfortunately, sometimes the nerves begin to excite themselves, much like when a public address system gets feed back from the speaker to the microphone and begins to squawk. This sometimes occurs when the nerve does not have something productive to do such as when an amputation has removed the real input from the nerve and it is lacking a real task. If something does not turn down the volume, the sensation can become terrible just like the terrible squawk from a speaker system. Medications and other techniques can help turn down the volume in a variety of ways. That will be an important part of our discussions regarding post operative pain in future articles.

Fortunately, there are built in nerve circuits and actions which can help turn down the intensity of sensations. This occurs naturally to all of us. You have certainly experienced smelling an unpleasant odor when you entered a room but then forgotten about it as you became used to it. This was because your brain directed your conscious attention away from the smell. Even if the smell did not go away, you might not think about it again until someone entering the room called it to your attention. Our brains can do this with painful impulses also, such as when you have a burn, a bruise, a cut, etc. The sensation of pain may become less even though the original injury has by no means healed.

There are some psychological techniques, such as meditation, relaxation, and other attention-directing activities, that can help diminish pain, or at least our attention to it. As was stated earlier, various medications can also play a role in diminishing perception of pain by the sensory cortex of the brain. There are other events, such as stress, anger, fatigue, and anxiety, which can enhance the feelings of pain and make them more bothersome. Many of the techniques we will discuss later work by facilitating or inhibiting various types of nerve transmissions.

When an amputation occurs, the nerve trunks are cut at the site of the amputation and the sensory nerve cells die and are discarded along with the amputated limb. This is the equivalent of the television transmission lines being cut and the camera being destroyed. The television screen, antenna, cable hook-up and television station may still be present and working. They are just no longer getting a valid input from that particular remote television unit. Since the sensory cortex of the brain, and the spinal cord, as well as all the intermediate connections, are still working, signals still come to the sensory cortex, even if they are not valid, real signals.  Some of the signals are like static, some are from other neural circuits, and some of it we have no real idea about. The fact remains-the person still can feel the limb that is no longer present because the part of the brain that does the feeling is still alive and well.

The cut nerve can generate sensations of its own. Any sensation that could be experienced by the nerve prior to injury can still be perceived by the brain, even if the limb is no longer present.  If the cut end of the nerve is squeezed or pinched, the nerve may be highly stimulated and send strong signals that appear to originate in the amputated part because this is where the nerve cell originally was located. Sometimes the feelings are electric tingling, like when the funny bone at the elbow is struck and electricity runs into the little finger. Other times the sensation is a deep, slow, burning pain.  Anything that the limb could have actually experienced when it was intact can still be experienced by the cut nerve and sensory cortex that is attached to it. Sometimes the experience may seem more intense because the sensory cortex is bored by having nothing to do and may seem to make a lot out of a little.

There are many important understandings which can come from the fairly simple neuroanatomy and neurophysiology which has just been discussed.  Much of how pain phenomena occur following an amputation can be explained by understanding what has happened to these systems and how it might make them behave. It is important to understand these basics so that we can make some sense from the information which will be discussed in future articles in this series. Understanding how we feel pain can help us understand the methods of relieving that pain.

I have received several requests for information and advice following the first article. Post-amputation pain problems are tragically common and that is precisely the reason that we are devoting space and time to doing this series of articles. Unfortunately, there is no way that I can answer individual questions. When I invited questions and comments, I tried to make it clear that the questions would be used to direct the future articles. That I will definitely try to do.

There is no safe and valid way that I can attempt to answer individual questions or solve individual problems.  If you have a problem that demands a quick, complete answer, please contact a comprehensive pain management program near you. If you do not know of one, you can ask your personal physician, the anesthesia or neurology department at a hospital or medical center near you, or contact your local medical society.  Direct help for specific problems must be done on a personal basis.

With these conditions restated, I will appreciate your questions and ideas to be incorporated into future articles. 

Send them to