The mystery of phantom pain: growing evidence for psychophysiological mechanisms.

The direct, and much of the indirect, evidence supporting the existence psychophysiological mechanisms for phantom limb pain is reviewed. Phantom pain is shown to be a symptom class composed of different, but similarly described problems, each having its own underlying mechanisms. At least some descriptive types of phantom pain probably have mainly peripheral, as opposed to only central, origins. Although much of the direct data are preliminary, burning phantom pain is probably related to decreased blood flow in the residual limb, while cramping phantom pain is mainly related to spikelike muscle spasms in the major muscles of the residual limb. Little support is provided for psychological causes for phantom pain, but the expression of phantom pain does appear to be influenced by psychological mechanisms similarly to the ways other chronic pain conditions are influenced. The importance of a careful psychophysiological assessment of patients to treatment success is discussed. Because several different mechanisms are involved, no one treatment is likely to be effective for all of the different types of phantom pain. Appropriate combinations of self-regulation strategies aimed at controlling the underlying physiological problems are likely to be effective in reducing the incidence and severity of burning and cramping types of phantom pain.