What is phantom limb pain?
Phantom limb pain is a common problem in people who have had a limb amputated. It occurs in a very large proportion of people after amputation, and can come on very soon after the procedure or at a later stage. The character of the pain can be very variable, with sensations including crushing, shooting and stabbing
Similar problems can occur in people who have other body parts removed, for instance after mastectomy or removal of the bladder or testicles.
Phantom pain often begins within a few days after surgery. Some people find that phantom pain and sensations decrease over time, whereas others experience them for many years. Pain that has gone untreated for more than a year tends to be more difficult to treat.
As well as pain in the absent limb, people can also experience pain in the stump.
Phantom limb sensation is another phenomenon experienced after amputation. This is a non-painful sensation of the existence of the amputated limb. It is very common indeed after amputation. Some people can find it distressing, and need to be reassured that it is essentially normal and if anything, when it comes to using an artifical limb, can be helpful.
What causes phantom limb pain?
We are not sure why people get phantom limb pain, but there are several theories. Here is a selection (which I have adapted, with thanks, from some information from Napp Ltd.):
- The damaged nerves at the limb may send out a mass of nerve signals, or special chemicals, which cause central sensitisation in a part of the spinal cord called the dorsal horn so that it has an exaggerated response to stimuli. Nerves that have been inactive in the spinal cord may also be activated
- The dorsal horn cells themselves may be firing random signals.
- There may be reorganisation of the nerves in the dorsal horn because of the limb injury. Small nerves that have been cut because of the injury or amputation will die. Larger nerves from the dorsal horn spread their endings to where these smaller nerves have died, to replace them. This means that signals from this area of the amputated limb can still get to the brain, and this might fool the brain into thinking the limb itself is still there.
- There may be reorganisation of the nerves in an area of the outer part of the brain called the sensory cortex. This can mean that the area responsible for receiving messages from a normal limb may begin to receive messages from other areas after the limb has been amputated. This is a bit like a short circuit, with the nerve wiring going to the wrong places. This may explain why phantom pain sufferers feel an increase in their phantom arm pain by touching part of their face on the same side of the body, as the face and hand areas are very close together on the brain map. This has been shown to correlate with changes in brain localised blood flow on functional MRI imaging. This is discussed in a detailed review article from Prof Herta Flor, whose group has done much of this research, which you can download as a pdf here.
It is unclear why some people get phantom limb pain and others do not. The following have been associated with an increased risk of developing phantom pain:
- Poorly controlled pain before amputation.
- Stress and emotion, perhaps associated with the amputation
- Persisting stump pain afterwards.
- Bilateral amputations (i.e. both legs or arms).
- Lower limb rather than upper limb amputation
What treatment may be needed?
Once established, phantom pain can be very difficult to treat. It is therefore very important to try to prevent it.
A great deal of research has been done into methods that may reduce the risk of development of phantom pain. It seems likely that techniques we used to use such as numbing the limb for days before an amputation with an epidural are less effective than had previously thought, though this is still sometimes done.
Certainly, good pain management before, during and after amputation is important in preventing or minimising possible causes of phantom limb pain. Various interventions at the time of amputation may make a difference, and we are currently formulating guidelines in our Trust for this. Good local anaesthetic techniques such as spinal anaesthesia, nerve catheters or epidurals used after surgery and drugs given during surgery may help.
If you do develop phantom limb pain, treatments that may be used include opioids (strong painkillers) , antidepressants (which are effective in treating pain as well as reducing depression), or anticonvulsants (which are used to treat epilepsy and also pain caused by excessive nerve signal firing). It may be helpful to inject around the stump nerve endings with local anaesthetic and steroids, if it is thought that the nerve endings that remain are responsible for the phantom pain. The nerve signals may be blocked with anaesthetics.
You may need surgery to refashion a stump where the nerve endings are thought to be too close to the load bearing area when wearing a prosthesis.
You may think that cutting the nerve or amputating the whole limb will stop the pain, but it will not. Destructive surgery can be effective for a few months, but pain always returns, frequently worse.
Spinal cord stimulation may sometimes work if other methods have not.
You may be offered mirror box therapy, a special form of therapy designed for phantom limb patients. You will be told to watch and exercise your normal limb inside the mirror box so that you can see a reverse mirror image of it. This fools the brain into thinking that the amputated limb is still there. You can try to imagine that you are moving the limb into a position where it stops hurting.
You may find transcutaneous electronic nerve stimulation (TENS - which uses small amounts of electricity to block pain signals), biofeedback, hypnosis, or relaxation techniques helpful
Pain Relief Foundation information sheet on Phantom Limb Pain
Wellcome Trust site on Phantom Limb Pain
Two articles which although written for medical professionals may be useful for others, from the International Association for the Study of Pain and the FRCAUK website
An article from the Wellcome Trust on Pphantom pain can be accessed here.
This site complies with the HONcode standard for trustworthy health information:
Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 15/02/2016