EDP column by Professor Ketan Dhatariya
Phantom limb pain is pain appearing to come from where an amputated limb used to be. To understand why people experience this kind of unpleasant sensation, one needs to understand how pain is perceived usually. The skin has lots of receptors that respond to different kinds of stimuli. For example, if you spilt hot teal on your hand, the nerve receptors responsible for detecting temperature would be activated, and send a signal to your brain telling it that they had been stimulated. The brain ‘knows’ that signals from those receptors means that things are ‘hot’ and you need to avoid doing that again. There is a nerve – rather like a wire – that connects the skin to the brain. The brain has areas within it that are associated with different parts of the body.
There are lots of theories about why phantom limb pain occurs. One of the main ones is that if a limb is amputated, then the nerves in the damaged area were removed, but the rest of the nerve that travels in the remaining part of the limb are still there. Damage to the end of the remaining nerve can lead to abnormal stimulation and signals being sent to the brain. Because the brain ‘knows’ that a signal from that nerve would usually be coming from the limb, it ‘thinks’ the missing limb is still there. There is then a conflict between the part of the brain that perceives pain, and the part of the brain that is aware that that part of the limb is missing. There are other theories as well, but this
Not all phantom limb sensations are painful. And it is not only missing limbs that generate these sensations. It can be any part of the body.
Treatment can be very difficult. There are a few medicines that can be used – often antidepressants or anticonvulsants. These can work by reducing the signals sent from the damaged part of the nerve, so reducing the pain. Other treatments include spinal cord stimulation to inhibit the signals further up the nerve before it gets to the brain. Other solutions include using more psychological techniques to allow the person to accept that the limb is no longer there and to ‘teach’ the brain to ignore those unwanted signals.
There are a variety of approaches. It is important that you talk to your doctor about the symptoms you have so that they can help decide what approach to take and maybe refer you to a specialist.
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