case report We will describe four patients with an obsessive-compulsive desire for amputation of a perfectly healthy part of one of their legs, a syndrome that has been called body integrity identity disorder (biid). Our four patients display typical characteristics of biid, such as the feeling that the limb is not a part of  their body, and the longing for surgical removal of the unwanted body part to feel complete. These patients are otherwise healthy, do not suffer from delusions or psychosis and are well educated with jobs and stable relationships. Although there is hardly any knowledge about the causes of biid, it as been suggested sensory information from a body part is not properly integrated in the brain, and might therefore not feel like your own. We will discuss new fmri findings on neural responses to touch and motor task in biid patients. The results show reduced activation during touch of the unwanted compared to the wanted body part in various multisensory regions and reduced motor activation when the toes of the unwanted leg compared to the wanted leg were moved. The brain regions correspond to regions previously implicated to be important for making distinctions between self and others and feelings of embodiment.
method It is fascinating that a small decrease in brain activity in these ‘body ownership areas’ might underlie a grave disorder and cause such lifelong distress to biid patients.