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THE ROLE OF THE SYMPATHETIC NERVOUS SYSTEM IN PHANTOM LIMB PAIN

This chapter is supported by Grant MT-12052 and a research scholarship from the Medical Research Council of Canada. After an amputation many patients awake from the anesthesia feeling certain that the operation has not been performed. They feel the lost limb so vividly that only when they reach out to touch it, or peer under the bed sheets to see it, do they realize it has been cut off. This phenomenon has been termed the phantom limb and is usually described as having a tingling or pins-and-needies quality. For purposes of description, classification, and treatment, it is useful to distinguish between the normal, nonpainful phantom limb, and the painful phantom limb. The nonpainful phantom is reported to develop within a day of amputation in approximately a third of patients, and by 8 days the incidence is near 85%.44 The percentage of amputees that experience a phantom limb 6 months and 2 years later does not change appreciably, although with time there is a significant decrease both in the frequency with which the phantom limb occurs as well as in the duration of episodes. For many amputees, however, a distressing problem is phantom limb pain (PLP).84 The pain may be an intensification of the tingling sensation that defines the nonpainful phantom limb, or it may consist of paroxysmal shooting pains that travel up and down the limb. The phantom limb may be reported to be in a cramped or unnatural posture that gives rise to excruciating pain. For many amputees, the phantom is the seat of an intense burning pain as if the hand or foot were being held too close to an open flame. In still others, the pain in the phantom limb is indistinguishable from the pain experienced in the