A small number of people have a burning desire to have a healthy limb amputated. Olaf Blanke from the Laboratory of Cognitive Neuroscience at the Ecole Polytechnique Federale de Lausanne has been conducting extensive interviews with 20 such people. His findings have cast doubt on the traditional view that this is a form of body dysmorphic disorder and suggest that it could be caused by abnormalities in the front-parietal circuits of the brain. 75% of the patients wanted their left leg amputated. They also reported abnormal sensations in the body parts they wanted removed including tingling and numbness, a loss of sensitivity, a feeling that the limb belonged to someone else or that it was already absent (a kind of phantom-limb sensation in reverse); all symptoms that are sometimes reported by people with damage to their fronto-parietal cortex. Contrary to how people feel in body-dysmorphic disorder none of the participants thought the 'offending' limb was defective or were embarrassed by it. Female patients tended to be more severely affected than men; the three women in the study all wanted to have multiple amputations.
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