| A large proportion of amputees (50 to 80 percent) | | | | stimulation from amputated limbs, being deprived of |
| experience the phenomenon of phantom limbs, | | | | input, actually expands into the surrounding brain, such |
| meaning they feel body parts that are no longer there. | | | | that an individual who has had an arm amputated will |
| These limbs can itch, ache, and feel as if they are | | | | experience unexplained pressure or movement on |
| moving. Some scientists believe it has to do with a kind | | | | their face or head. The individual may also experience |
| of neural map that the brain has of the body, which | | | | some trauma as well as emotional discomfort. In many |
| sends information to the rest of the brain about limbs | | | | cases, the phantom limb aids in adaptation to a |
| regardless of their existence. | | | | prosthesis, as it permits the person to experience |
| Phantom sensations and phantom pain may also occur | | | | proprioception of the prosthetic limb. |
| after the removal of body parts other than the limbs, | | | | Another side-effect can be heterotopic ossification, |
| e.g. after amputation of the breast, extraction of a | | | | especially when a bone injury is combined with a head |
| tooth (phantom tooth pain) or removal of an eye | | | | injury. The brain signals the bone to grow instead of |
| (phantom eye syndrome). A similar phenomenon is | | | | scar tissue to form, and nodules and other growth can |
| unexplained sensation in a body part unrelated to the | | | | interfere with prosthetics and sometimes require |
| amputated limb. It has been hypothesized that the | | | | further operations. |
| portion of the brain responsible for processing | | | | |