Mechanisms of distorted body representation and neurorehabilitation

Phantom limb refers to a phenomenon whereby the patient still feels sensation and movements originating in the missing part after amputation. The patient is therefore aware of a part of the body that does not actually exist. The patient may also experience pain at this site, despite the actual body part not existing. Such a condition is referred to as phantom limb pain. Asomatognosia, however, refers to loss of awareness of a part of the body. It is a state in which the patient’s awareness of their body differs from reality. While this condition is normally widely–recognized as occurring after brain injury and right hemisphere damage in particular, it has been found to occur in many cases of neuropathic pain such as complex regional pain syndrome. In such cases, these are termed neglect–like symptoms. Thus, physical modification such as declines in sense of ownership and sense of agency may also be noted in motor disorders. Such cases involve dysfunction of the parietal lobe, which is involved in body representation. Therefore, in recent years, techniques for approaches to brain dysfunction similar to rehabilitation for stroke patients have been developed for cases of phantom limb not associated with brain damage and cases of motor disorders. The effects of such techniques are gradually being demonstrated. In this review, we described distorted body representation mechanisms from the viewpoints of neuro -phenomenology, neuropsychology and neurophysiology, and present the newly developed technique termed neurorehabilitation.