Phantom Pain as an Expression of Referred and Neuropathic Pain

Abstract

The neural mechanisms that permit perception of phantom limbs have been investigated over many years (Melzack, 1989a; Sherman, 1989a, 1989b; Sherman, Arena et al., 1990). A basic explanation of the underlying concepts is included in the attached amputee guide (Appendix II). A huge body of research has demonstrated that sensations reaching the brain are identified as to location on the skin by the homunculi in the sensory parts of the brain, including the somatosensory cortex, which contains several representations of the entire body surface. Thus, a pinch of the left index finger tip stimulates neurons in a location on the homunculi representing the left index finger tip. If the finger has been amputated, and the same signal is started by stimuli anywhere along the remaining nerve paths between the finger’s stump and the homunculi, the resulting sensation seems to emanate from the finger tip. The real question is how these misleading impulses form and why the resulting sensation is frequently, but not always, painful. The relationships among phantom pain, phantom sensations, and possible changes in the homunculi are discussed in this and subsequent chapters.