Phantom perceptions are an intriguing mystery that captured and still captures the attention of many people: those who are amputated, their relatives, healthcare providers, and even the public. Indeed, it is a mystery: How is it possible to feel sensations and/or motions in a limb or a body part that has obviously been surgically removed? Unfortunately, there is no clear answer to this question. Phantom sensations and especially phantom limb pain remain medical nightmares. Moreover, we can currently not explain why phantom sensations occur in some amputees but do not in others. In the present chapter, we will first report on locations, characteristics, and descriptions of phantom sensations. We then will report on patho-physiological mechanisms that possibly might lead to phantom sensations. Finally, therapeutic options and possible future directions of research and treatment will be given.
Locations, characteristics, descriptions of phantom sensations
As a result of amputation of an extremity in adults, nearly all individuals experience phantom sensations in those parts of the body that are now absent. Many amputees report on a progression of their feelings over time. Immediately after amputation, most patients claim on feelings of a phantom limb that mimics the removed body part in size and detail. Sometimes, this phantom is reported to remain in an unusual position as it occurred to be as the result of the previous injury. This phantom body part usually moves gradually into the distal end of the residual limb, a process that is called telescoping. During this telescoping, the residual limb usually progressively loses details in somatosensory detail from proximal to distal. Figure 1 illustrates this process.
Interviews revealed that telescoping occurred at some point in time after amputation in nearly two-thirds of the amputees interviewed [1, 2]. Furthermore, according to these studies, amputees reported on normal sensations of the limb including the whole spectrum of somatosensory sensations, i.e., temperature, proprioception, mechanical sensations like pressure or vibration. Moreover, most patients reported also on the perceived ability to control motion of the phantom limb. Motions could be voluntary, but spontaneous, automatic reflexive as in motions relating to losing balance . However, telescoping usually does not occur in patients that report on a special phantom sensation, i.e., phantom limb pain.