Wikipedia
Somatoparaphrenia is a type of monothematic delusion where one denies ownership of a limb or an entire side of one's body. Even if provided with undeniable proof that the limb belongs to and is attached to their own body, the patient produces elaborate confabulations about whose limb it really is, or how the limb ended up on their body. In some cases, delusions become so elaborate that a limb may be treated and cared for as if it were a separate being.
Somatoparaphrenia differs from a similar disorder, asomatognosia, which is characterized as loss of recognition of half of the body or a limb, possibly due to paralysis or unilateral neglect. Asomatognosic patients may, for example, mistake their arm for the doctor’s arm, however, can be shown their limb and this error is temporarily corrected.
Somatoparaphrenia has been reported to occur predominately in the left arm of one's body, and it is often accompanied by left-sided paralysis and anosognosia (denial or lack of awareness) of the paralysis. The link between somatoparaphrenia and paralysis has been documented in many clinical cases and the question arises as to whether or not paralysis, anosognosia or both are necessary for somatoparaphrenia to occur.