What is phantom limb pain?
Phantom limb pain refers to pain that occurs in an absent limb. The limb may have been lost due to a traumatic injury or amputated during an operation because of a disease. Phantom limb pain is the most common complication following an amputation (it is estimated that between 50-80% of all people will develop phantom limb pain following an amputation). It is more commonly reported by women than men and appears to be more common in people who have undergone an upper limb (ie hand, arm) rather than lower limb (ie leg, foot) amputation.
The term ‘phantom’ does not mean that the pain felt is not real. Phantom limb pain is a very real condition that has been confirmed by brain imagery showing how nerve signals are transmitted to the brain. Most people will develop phantom pain a few days after their operation or injury however phantom limb pain may begin months or even years following an operation or injury. While many people find that once they have phantom limb pain it continues for many years sometimes the pain does improve with time.
Causes of phantom limb pain
The cause of phantom limb pain remains unclear however there are three theories to why it may occur:
- one theory is that the nerve endings around the stump of the amputated limb form into clusters called ‘neuromas’. These are thought to generate abnormal electrical impulses that the brain interprets as pain.
- another theory suggests that the lack of sensory input from the amputated limb causes a chemical change in the central nervous system of the body. This then leads to confusing signals being sent to the brain which triggers feelings of pain.
- another theory is that the brain has a memory of the removed limb and its associated nerve signals and that the feelings of pain are due to the brain attempting to recreate this memory but not being able to.
Symptoms of phantom limb pain
The symptoms of phantom limb pain can range from mild to severe and usually comes in bursts. Only a few people will experience constant pain. Some people will have several bursts of pain each day while others less than once a week. Phantom limb pain is usually felt at the end of the amputated limb in phantom toes and fingers and is described as shooting, stabbing or burning pain (neuropathic pain).
The amputated limb will often feel shorter (‘telescoping’) that what it was and may feel like it is in a distorted and painful position. The pain is often made worse by anxiety, stress and weather changes.
Diagnosis of phantom limb pain
A doctor will be able to make a diagnosis of phantom limb pain based on the description of the pain and feelings in the phantom limb.
Treatment
- Analgesia
Over-the-counter pain medications such as paracetamol or Ibuprofen have little or no effect on phantom limb pain.
Low dose tricyclic antidepressants (TCAs) have been shown to help with the nerve pain of phantom limb pain. Side effects of Amitriptyline include a dry mouth, drowsiness, constipation and nausea.
Anticonvulsants have also been found to have benefit in the treatment of phantom limb pain. Side effects include dizziness, light-headedness, nausea and vomiting.
Other treatments
- Prosthesis and rehabilitation
Phantom pain can often be helped by use of an artificial limb (prosthesis). Using the affected limb as much as possible will help to lessen the pain. Evidence suggests that successful rehabilitation can reduce the amount of phantom pain experienced.
- Mirror visual feedback
This treatment is still in the experimental phase. A mirror is placed so that it reflects the opposite limb making it appear as though the amputated limb has returned – when the opposite limb moves the phantom limb is seen to move as well. The phantom limb may also be felt to move (‘kinaesthetic sensation’). If this treatment is used over a prolonged period of time the phantom limb pain may disappear.
- Spinal Cord Stimulator (SCS)
Spinal Cord Stimulators may be an effective treatment for those assessed by a pain specialist. An electrode is implanted next to the spinal cord and connected to a programmable generator implanted under the skin in the buttock. The SCS generator produces electrical impulses that are sent to the spinal cord via the electrode. These impulses block pain signals before they reach the brain by replacing them with a tingling sensation, thereby lessening the pain felt in the phantom limb.
Psychological impact of an amputation
Having an amputation may result in the need for psychological treatment. This is because a person has to cope with the amputation of their limb which results in a loss of function and a change in their body image. It is very common for people to experience feelings of depression, anxiety, denial and grief when they have phantom limb pain. Engaging with clinical psychology as part of a management plan is recommended for this reason.
