Scratching the phantom itch.

From an article on neuroplasticity:

An amputee has a bizarre itch in his missing hand: unscratchable, it torments him. A neuroscientist finds that the brain cells that once received input from the hand are now devoted to the man’s face; a good scratch on the cheek relieves the itch. Another amputee has 10 years of excruciating “phantom” pain in his missing elbow. When he puts his good arm into a box lined with mirrors he seems to recognize his missing arm, and he can finally stretch the cramped elbow out. Within a month his brain reorganizes its damaged circuits, and the illusion of the arm and its pain vanish.