The brain's sensory cortex, which receives and interprets incoming information, maintains a representation of the body physically within itself. The homunculus is the name given to the diagram obtained when each part of the body is plotted against its place on the sensory cortex, with more important areas of the body being illustrated as larger areas of the brain. Various areas, such as the hands and the lips, take up much more brain area due to their importance in normal function, and it is these most important areas to control which need greater sensory awareness and greater processing power to work out responses.
When we suffer an injury the pain comes directly from that part, streaming in from the highly irritated nerve ends and the normally silent nerves woken up by the chemical soup of the injury. As the barrage of impulses comes in to the spinal cord it meets the second stage nerves which will take the messages on into the central nervous system. These second stage nerves become highly excited by the incoming torrents of impulses and amplify the signal significantly, passing on much higher pain levels to the higher brain centres.
To feel any pain our higher brain areas such as our sensory cortex and our conscious interpreting minds must receive the pain impulses as pain is not present until it gets right through. No pain is imaginary but the brain builds a virtual feeling reality in order to interpret the world and be able to respond, a virtual reality involving sight, touch and pain. It's vital to understand the concept that the brain is what makes the reality of the pain and not the injured, damaged or abnormal body part.
Amputation causes a much greater disruption of the body's systems than appears obvious on the surface as it is not just the ligaments, muscles and bones which are surgically cut. The nerves which travel down the limb are also cut across and this has profound repercussions as the nervous system does not appreciate it when input from the body is cut off. When the constant streams of information coming in are cut off the nervous system reacts in abnormal ways which can cause unpleasant pain syndromes which are hard to treat.
When normal incoming impulses are blocked from reaching the second stage spinal cord nerves these nerves overreact by becoming highly irritable and increasingly active. Due to the nerve transection and the complete loss of sensory input the second stage nerves start to go into business on their own, firing off pain signals without any incoming stimulation. As the sensory areas in the brain for the leg or other amputated part are still present, when they receive the spontaneous inputs from the overexcited second stage nerves they interpret them as pain in the area where the nerve used to come from originally.
Phantom pain is the name given to pain which is present in a part which does not exist any longer. It is a common consequence of amputation with a high proportion of amputees reporting a pain problem which can come on over weeks and months. This pain can be very troubling, more troubling than most typical pains, due to its unpleasant nature which can be very sharp or deep and throbbing. Phantom pain is an example of neuropathic pain, a pain generated by the nervous system rather than by current injury to bodily tissues as in normal pain.
Neuropathic pain is difficult to treat with morphine type drugs such as fentanyl, codeine, morphine or tramadol and more common agents against this sort of pain are gabapentin, amitriptyline and pregabalin. Physical treatment agents such as transcutaneous electrical nerve stimulation may be used by attaching small electrodes to the skin and transmitting pain reducing signals to the central nervous system. Cognitive therapy may be necessary to help patients manage the problems of a long term pain.
Many patients with an amputation have a serious, long term problem in phantom pain, with severe pre-operative pain perhaps predisposing them to pain difficulties after operation. Involving a pain clinic with its multidisciplinary management from the team is a good approach. - 16650
When we suffer an injury the pain comes directly from that part, streaming in from the highly irritated nerve ends and the normally silent nerves woken up by the chemical soup of the injury. As the barrage of impulses comes in to the spinal cord it meets the second stage nerves which will take the messages on into the central nervous system. These second stage nerves become highly excited by the incoming torrents of impulses and amplify the signal significantly, passing on much higher pain levels to the higher brain centres.
To feel any pain our higher brain areas such as our sensory cortex and our conscious interpreting minds must receive the pain impulses as pain is not present until it gets right through. No pain is imaginary but the brain builds a virtual feeling reality in order to interpret the world and be able to respond, a virtual reality involving sight, touch and pain. It's vital to understand the concept that the brain is what makes the reality of the pain and not the injured, damaged or abnormal body part.
Amputation causes a much greater disruption of the body's systems than appears obvious on the surface as it is not just the ligaments, muscles and bones which are surgically cut. The nerves which travel down the limb are also cut across and this has profound repercussions as the nervous system does not appreciate it when input from the body is cut off. When the constant streams of information coming in are cut off the nervous system reacts in abnormal ways which can cause unpleasant pain syndromes which are hard to treat.
When normal incoming impulses are blocked from reaching the second stage spinal cord nerves these nerves overreact by becoming highly irritable and increasingly active. Due to the nerve transection and the complete loss of sensory input the second stage nerves start to go into business on their own, firing off pain signals without any incoming stimulation. As the sensory areas in the brain for the leg or other amputated part are still present, when they receive the spontaneous inputs from the overexcited second stage nerves they interpret them as pain in the area where the nerve used to come from originally.
Phantom pain is the name given to pain which is present in a part which does not exist any longer. It is a common consequence of amputation with a high proportion of amputees reporting a pain problem which can come on over weeks and months. This pain can be very troubling, more troubling than most typical pains, due to its unpleasant nature which can be very sharp or deep and throbbing. Phantom pain is an example of neuropathic pain, a pain generated by the nervous system rather than by current injury to bodily tissues as in normal pain.
Neuropathic pain is difficult to treat with morphine type drugs such as fentanyl, codeine, morphine or tramadol and more common agents against this sort of pain are gabapentin, amitriptyline and pregabalin. Physical treatment agents such as transcutaneous electrical nerve stimulation may be used by attaching small electrodes to the skin and transmitting pain reducing signals to the central nervous system. Cognitive therapy may be necessary to help patients manage the problems of a long term pain.
Many patients with an amputation have a serious, long term problem in phantom pain, with severe pre-operative pain perhaps predisposing them to pain difficulties after operation. Involving a pain clinic with its multidisciplinary management from the team is a good approach. - 16650
About the Author:
Jonathan Blood Smyth is a Superintendent of Physiotherapy at an NHS hospital in the South-West of the UK. He specialises in orthopaedic conditions and looking after joint replacements as well as managing chronic pain. Visit the website he edits if you are looking for physiotherapists in Manchester.
