Phantom Limb Pain

4 Apr 2018

Amputation of a limb is generally as a result of a severe infection in the limb, gangrene, often as a result of peripheral arterial disease, serious trauma such as a crush or blast wound or deformity which affects movement and function.  Whilst common sense suggests that amputation for the relief of chronic pain must be undertaken as a last resort, it happens more often than perhaps realised.  Substantial trauma to the musculoskeletal structure of a limb may mean that the most suitable orthopaedic treatment is its surgical removal. However, if there is a neuropathic element to the pain, amputation may not be effective and can even exacerbate the existing pain further.

 

Defining Phantom Limb Pain

Phantom limb pain refers to pain in the area that has previously been amputated and commonly occurs in amputated limbs,  it also occurs in post-mastectomy patients. Despite the fact that the limb has been surgically removed, the nerves that supply the limb, albeit severed, may still be functioning and signalling back to the brain that there is pain occurring. This part of the brain feels but does not think – it has always felt the limb is there and will continue to sense the limb is there, even though it has been removed.

Recent research also indicates that after nerves have been operated on, including limb amputation, there is new nerve growth in the brain. This may also result in the sensation of phantom limb pain. Correct diagnosis of the cause of pain before amputation is vital, as the removal of the limb will not necessarily treat the damaged neural pathway, and a patient can be left with persisting pain despite the procedure.

 

Post-Amputation Pain

Pain experienced following an amputation procedure is very common and part of the natural healing process. The body will have experienced significant trauma, with muscles, nerves and bone being removed from the body. Subsequent inflammation of the nerves and tissue are how the body responds to feeling pain.

Six of the most effective treatment methods are:

Mirror box therapy This is a very specific type of physical therapy with proven efficacy for patients with post-amputation pain. The patient actually watches in a mirror while receiving physical therapy to re-map the brain’s neural pathways to register that the limb is no longer there.

Local injection therapy – The physician injects a local pain-blocking agent at the amputation site. This can calm the painful signals sent by the nerve endings to the brain.

Non-opiate analgesia – These prescription pain medications slow or limit how the painful nerves send signals to the brain.

Deep brain stimulation – In this technique, a surgeon places tiny electrodes directly on the surface of the brain to help attenuate pain with electrical impulses.

Nerve cuff stimulation – This technique is relatively new and involves placing a nerve stimulator on the nerves travelling to the amputated limb. The nerve stimulator resembles the wrapper on a straw but is only about a centimetre long. It has a small electrode inside of it and encases the nerve itself. Rather than blocking the nerve signals, it sends a pleasant signal through the nerve. Patients tolerate the procedure quite well and can activate the cuff on the nerve ending via a small wireless remote control. When they begin to feel pain, they press a button and the device delivers an imperceptible electrical stimulation to replace the pain sensation as it travels to the brain.

Spinal Cord Stimulation – There is little information on results of SCS on phantom limb pain but what there is suggests it can be effective.  It works by delivering mild electric stimulation to the nerves along the spinal column to modify nerve activity to minimise the sensation of pain reaching the brain.

 

Phantom Limb Pain Prognosis

Because of the wide variety of pain that may be experienced and the distress phantom limb pain causes to patients on a number of levels, there is no one single way to manage post limb amputation pain. For example, the psychological aspect requires great care and ongoing management by an expert with experience in this field. Each person has to be evaluated individually and his or her pain managed with a treatment pathway that is continually monitored with regular reviews undertaken to ensure their pain is managed as effectively as possible.

 

Dr Jenner and Dr Ramos-Galvez offer consultations within 7 days and a full report within 4 weeks. Both are skilled consultants in pain medicine who specialise in the treatment of CRPS. If you would like to instruct them, please contact 0207 118 0650, info@medicolegal-associates.com or go to our contact page.