New insights into amputation desire

In the late Summer of 1997, the surgeon Robert Smith deliberately amputated the healthy lower left leg of his patient, 38-year-old Kevin Wright, who had been yearning for this outcome since childhood.

Back in the 90s, Wright's condition was judged to be a form of body dysmorphic disorder - a psychiatric diagnosis characterised by an irrational belief that there is something defective with a body part. Before now, there has been little systematic research with patients experiencing amputation desire, but in a new study, Olaf Blanke and colleagues have reported the results of extensive interviews they've conducted with 20 such patients. Blanke's findings have led his team to speculate that rather than being a form of body dysmorphic disorder, amputation desire might be more accurately construed as a neurological syndrome, related to a dysfunction in the way the body is represented in the fronto-parietal circuits of the brain - a condition they've labelled "body integrity identity disorder".

Supporting their account, Blanke's team point to the fact that 75 per cent of the interviewed patients specifically wanted their left leg amputated, or if they wanted both legs amputated, then the desire was predominantly for the left leg (which is represented and controlled by the right hemisphere of the brain).

Moreover, 13 of the participants reported abnormal sensations in the body part they wanted removed, including tingling and numbness, loss of sensitivity, the feeling that the limb belongs to someone else, or that it is already absent (almost like an inverted form of phantom limb syndrome). These were not delusions because the patients knew that in reality, the limb was theirs and was there. Crucially, however, these kinds of abnormal sensations are sometimes reported by patients with damage to the fronto-parietal cortex.

Contrary to the body dysmorphic diagnosis, none of the patients thought their limb was defective, nor were they embarrassed by it.

"Collectively, our data suggest that amputation desire might be conceptualised as chronic asomatognosia [lack of awareness of a body part] or a negative form of the phantom limb phenomenon," the researchers said, adding that the condition appeared to have much in common with gender identity disorder, which is associated with a desire to change sex. However, the researchers cautioned that there is a need for more in-depth neurological examinations with a larger sample of patients.

Several other curious findings emerged. For example, there appeared to be a sex difference in amputation desire. Whereas 12 of the 17 male patients desired the amputation of a single limb, the three female patients all wished for multiple amputations - one wanted all her limbs removed, one wanted to lose two legs and an arm, and the other wanted both legs truncated.

Among the patients' descriptions of their amputation desire were the following typical accounts: "It [the leg] feels foreign and it does not belong to me", "I should not have been born with my legs", and "My leg is somehow too much, I am not connected to my body".
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Blanke O, Morgenthaler FD, Brugger P, & Overney LS (2009). Preliminary evidence for a fronto-parietal dysfunction in able-bodied participants with a desire for limb amputation. Journal of neuropsychology, 3 (Pt 2), 181-200.

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