The term “phantom limb” is used to designate the illusion of the persistent presence of a limb after it has been amputated. It is a remarkable fact that the great majority of patients who have had a limb removed will retain, long after the stump has healed, perhaps for the remainder of their lives, a vivid sense of the presence of the absent member. Often the vivid quality of the sensory illusion causes the patient to be more aware of the phantom than of the normal limb. Sometimes the sensations are distressing and occasionally there is a degree of pain that so preoccupies the patient as to destroy his social usefulness.