When nerves have been cut across or when inflammation persists in the tissues, abnormal chemicals are transported to the cord by C fibres. These exaggerate the excitability of the spinal cord transmitting system. Worse, they immobilize the turn-off mechanism in the spinal cord, represented by the small white circle cells. Small inputs result in large outputs. In the extreme, these hyperexcitable cells begin firing by themselves, sometimes in bursts and sometimes steadily.
The amputees showed all of these changes. All of them had patches of skin on their stumps which were exquisitely sensitive, even though the sensitive tissue had never been injured. All of them had clearly perceived phantom limbs some of which were felt as continuous pain described as hot, burning or cramping. Some had stabs of pain which seemed to penetrate the whole missing limb and which shook the whole body so that one could witness the man's reaction by his blanching of the face, gripping and tensing.