Supernumerary phantoms: a comment on Grossi, et al.'s (2002) spare thoughts on spare limbs.

A recently published case report of a supernumerary phantom limb in a man with left-sided hemiplegia did not take note that this phenomenon has been extensively documented in the neurological literature for well over 100 years. The present comment provides a brief introduction to the clinical and experimental approaches to supernumerary phantom limbs. It also emphasizes the theoretical importance of this condition for understanding the neurological mechanisms subserving the experience of having a body.