Phantom limb

A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 60 to 80% of individuals with an amputation experience phantom sensations in their amputated limb, and the majority of the sensations are painful. Research continues into the mechanisms underlying phantom limb pain (PLP) and into effective treatments to control it. A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 60 to 80% of individuals with an amputation experience phantom sensations in their amputated limb, and the majority of the sensations are painful. Research continues into the mechanisms underlying phantom limb pain (PLP) and into effective treatments to control it. Most (80% to 100%) of amputees experience a phantom with some non-painful sensations. The amputee may feel very strongly that the phantom limb is still part of the body. People will sometimes feel as if they are gesturing, feel itches, twitch, or even try to pick things up. The missing limb often feels shorter and may feel as if it is in a distorted and painful position. Occasionally, the pain can be made worse by stress, anxiety and weather changes. Phantom limb pain is usually intermittent. The frequency and intensity of attacks usually declines with time. Some people who have undergone gender reassignment surgery have reported the sensation of phantom genitals. The reports were less common among post-operative transsexual women, but did occur in transsexual men. Similarly, subjects who had undergone mastectomy reported experiencing phantom breasts; these reports were substantially less common among post-operative transsexual men, but did occur in transsexual women. For many years, the dominant hypothesis for the cause of phantom limbs was irritation in the peripheral nervous system at the amputation site (neuroma.) By the late 1980s, Ronald Melzack had recognized that the peripheral neuroma account could not be correct, because many people born without limbs also experienced phantom limbs. According to Melzack the experience of the body is created by a wide network of interconnecting neural structures, which he called the 'neuromatrix.' In 1991, Tim Pons and colleagues at the National Institutes of Health (NIH) showed that the primary somatosensory cortex in macaque monkeys undergoes substantial reorganization after the loss of sensory input. Hearing about these results, Vilayanur S. Ramachandran hypothesized that phantom limb sensations in humans could be due to reorganization in the human brain's somatosensory cortex. Ramachandran and colleagues illustrated this hypothesis by showing that stroking different parts of the face led to perceptions of being touched on different parts of the missing limb. Later brain scans of amputees showed the same kind of cortical reorganization that Pons had observed in monkeys. Maladaptive changes in the cortex may account for some but not all phantom limb pain. Pain researchers such as Tamar Makin (Oxford) and Marshall Devor (Hebrew University, Jerusalem) argue that phantom limb pain is primarily the result of 'junk' inputs from the peripheral nervous system. Despite a great deal of research on the underlying neural mechanisms of phantom limb pain there is still no clear consensus as to its cause. Both the brain and the peripheral nervous system may be involved.