Our brains hold a representation of our body within them, a mental picture of the different parts of the body which is situated in our brain sensory cortex. The sensory cortex is programmed to look after particular parts of the body and this representation is known as the homunculus. Different parts of the body such as the lips and the hands are highly represented as body areas which need lots of brain control to understand what's going on. These areas of the body are much more important for managing our daily lives and are represented much more strongly in the region of the brain devoted to them.
An injured tissue releases inflammatory chemicals which both cause local pain nerves to fire off and wake up pain nerves which normally don't participate much. As the levels of nerve impulses increase up towards the spinal cord, the second stage nerves there become overexcited and begin to amplify the incoming messages, cranking up the pain levels transmitted up to the brain. This amplification of incoming nerve impulses is known as central sensitisation, occurring in every acute pain state but persisting in central pain states such as neuropathic pain, of which phantom pain is an example.
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 incoming impulses are completely prevented from reaching the second stage nerves, these nerves react by rapidly increasing their excitability. With no incoming messages due to the amputation or nerve transection, the second stage nerves start to fire off spontaneously, that is for no particular reason but just because they are over-excited. The leg nerves may be missing but all the central nervous system transmission nerves for the leg still exist. The areas of the brain looking after the missing part are still present and still capable of creating pain in that missing part.
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.
Amputation can be followed by a serious and hard to treat pain syndrome which may be more severe if there was a lot of pain in the limb before the operation was performed. Referral to pain clinic with its access to a multidisciplinary pain treatment team is a useful step. - 16004
An injured tissue releases inflammatory chemicals which both cause local pain nerves to fire off and wake up pain nerves which normally don't participate much. As the levels of nerve impulses increase up towards the spinal cord, the second stage nerves there become overexcited and begin to amplify the incoming messages, cranking up the pain levels transmitted up to the brain. This amplification of incoming nerve impulses is known as central sensitisation, occurring in every acute pain state but persisting in central pain states such as neuropathic pain, of which phantom pain is an example.
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 incoming impulses are completely prevented from reaching the second stage nerves, these nerves react by rapidly increasing their excitability. With no incoming messages due to the amputation or nerve transection, the second stage nerves start to fire off spontaneously, that is for no particular reason but just because they are over-excited. The leg nerves may be missing but all the central nervous system transmission nerves for the leg still exist. The areas of the brain looking after the missing part are still present and still capable of creating pain in that missing part.
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.
Amputation can be followed by a serious and hard to treat pain syndrome which may be more severe if there was a lot of pain in the limb before the operation was performed. Referral to pain clinic with its access to a multidisciplinary pain treatment team is a useful step. - 16004
About the Author:
Jonathan Blood Smyth is Superintendent of a large team of Physiotherapists at an NHS hospital in Devon. 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 Edinburgh or elsewhere in the UK.
