Wednesday, August 14, 2013
When a leg has been removed, for any reason, the image of the leg remains as a phantom and you may alight from your bed after a sound sleep and attempt to stand on something that is not there. The cortical imprint of your leg in the brain remains for some period of time despite the sensory input that no longer exists. This is called the phantom image. The larger map of neural areas in the brain for the lower limb are the joints, knee, ankle and the great toe. These are the phantom images identified most commonly by the patient, but as the brain adapts to the loss of limb, recognition occurs that there is a forshortening of the phantom towards the stump end, rather than just fading away. Before it fades the foot is felt on the end of the stump. If a history of severe chronic pain has been present for some time in the affected limb before amputation, then rather than just a phantom image alone, phantom pain will sometimes ensue. The brain we now know has a self adjusting ability to add or delete mapped areas that serve the body as needed and it is is increasingly understood, but change is slower and less deliberate than we might wish, nevertheless the brain has infinite potential to adapt in time. Where chronic pain has been present it is probable that the cortical representation is larger and adapts more slowly. Given this mystery of pain, or image, where the limb source no longer exists, it should follow that pain in other parts of the human vessel we call our own could still be remembered despite all manner of conditions that now no longer show any discernible problem of pathology. Phantom pain in the back, gallbladder, shoulder disorders or a legion of other painful conditions that defy explaination are not entirely dissimilar to phantom pain following limb amputation that is clinically unquestioned even if still ill understood. When they said in that scheme of things, that it's all in your head, it would have a different meaning if the analogy to phantom limb is a viable theory. Then it might mean, it's still on your cerebral cortex for a while and wait till the three pounds of grey matter remaps itself. It may be a simpleton's theory for a high powered neurophysiologist, but I am long in the tooth and too short of time to shut up.