What is "allochiria"

n. A neurological disorder in which the patient responds to stimulus presented to one side of their body as if presented at the opposite side.

Allochiria (from the Greek meaning "other hand") is a neurological disorder in which the patient responds to stimuli presented to one side of their body as if the stimuli had been presented at the opposite side. It is associated with spatial transpositions, usually symmetrical, of stimuli from one side of the body (or of the space) to the opposite one. Thus a touch to the left side of the body will be reported as a touch to the right side, which is also known as somatosensory allochiria. If the auditory or visual senses are affected, sounds (a person's voice for instance) will be reported as being heard on the opposite side to that on which they occur and objects presented visually will be reported as having been presented on the opposite side. Often patients may express allochiria in their drawing while copying an image. Allochiria often co-occurs with unilateral neglect and, like hemispatial neglect, the disorder arises commonly from damage to the right parietal lobe.

Allochiria is often confused with alloesthesia, also known as false allochiria. True allochiria is a symptom of dyschiria and unilateral neglect. Dyschiria is a disorder in the localization of sensation due to various degrees of dissociation and cause impairment in one side causing the inability to tell which side of the body was touched.