Friday, February 19, 2021

The People Who Desire to Amputate Their Healthy Legs: The Neural Correlates of Body Ownership



People with Body Identity Integrity Disorder (BIID)--also called Body Identity Dysphoria--feel that their legs or arms are so alien to them that they obsessively think about their need to amputate them, although their limbs are perfectly healthy.   For half or more of these people amputation is sexually arousing, and they seek out amputees for sexual relations.  Most of them are men, although a few are women.  

The feeling of estrangement from one of their legs or arms begins when they are children and lasts throughout their life.  For most of them, it's the left leg that they want to be rid of.  And there's a clear line on the leg where they want the amputation--perhaps just below or above the knee.  Below that line, they have sensation and control over the leg, but they feel they won't be "complete" until that part of their leg is removed.

A few of them have found surgeons willing to amputate a healthy leg, and they report that they feel fine about themselves after the amputation.  There are some reports, however, that even after an amputation, those will BIID might then become unhappy with other limbs that they want to amputate.  Most surgeons refuse to do this because it seems to be a clearly unethical form of medical malpractice.  Some of those with this disorder will find ways to intentionally mangle their leg so badly that a surgeon will agree that amputation is necessary.

For most of us this is incomprehensible, because we identify with our whole bodies as belonging to us; and the idea of amputating one of our healthy limbs is horrifying.  We all normally have a sense of bodily self-ownership.  But why and how do we have that sense of self-embodiment?  If we could explain what the people with this disorder lack, that might explain what normal people have that sustains their identification of self and body.

Thinking about this disorder also raises questions about my account of the 20 natural desires, particularly the desires for sexual identity, sexual mating, and bodily health.  Are the people with this disorder expressing these natural desires in their desires for amputation and the sexual satisfaction associated with amputation?  Or are their desires unnatural because they are abnormal?  Or are they natural in the sense that they have natural causes?  If the good is the desirable, would it be good for them to satisfy their unusual desires?  In a free society, should they be free to have surgeons amputate their healthy limbs if this is what they need to be happy?  (I have written about the 20 natural desires here and here.)

Body Identity Dysphoria is so rare that there was little public knowledge of it until about forty years ago.  But in recent years, there has been a growing body of scientific research--psychological and biological--studying this condition (Sedda and Bottini 2014). 

The first public recognition of this disorder was in 1972 in a series of letters published in the men's magazine Penthouse.  The writers described their erotic obsession with having their healthy limbs amputated.  Some of them reported that they had succeeded in doing this.  For some of the readers this was so unbelievable that they thought it was a prank.


PSYCHIATRIC/PSYCHOLOGIAL EXPLANATIONS

In 1977, the famous "sexologist" John Money of Johns Hopkins University and Hospital published the first scientific report about this disorder (Money 1977).  In 1965, Money had established the Gender Identity Clinic at Johns Hopkins.  In 1966, the Johns Hopkins Hospital began performing sexual reassignment surgeries for transsexuals who wanted to change their bodies through surgery and hormone treatment to conform to their gender identity--men becoming women or women becoming men.  Money had actually coined the term "gender identity" in the 1950s.  (I have written posts on Money, intersexuality, and the desire for sexual identity herehere, and here.)

Money's article was about two men who had come to Johns Hopkins asking for the amputation of a healthy limb.  Having heard about the sex change surgeries for transsexuals at Hopkins, they assumed that they could find surgeons there willing to amputate their limbs to satisfy their sexual fantasy of being an amputee.  Money offered them psychological counselling, but he refused to refer them for surgical amputation.

He identified their condition as a paraphilia that he called apotemnophilia.  Using words derived from Greek words, he had popularized the term paraphilia--"love (philia) beyond (para) the usual"--as a non-pejorative substitute for words like "sexual perversion." He coined the word apotemnophilia to denote "amputation love"--"away from" (apo), "piece cut off" (temno), "love" (philia).  The American Psychiatric Association adopted Money's term paraphilia for the Diagnostic and Statistical Manual of Mental Disorders, in which the "paraphilic disorders" include sexual conditions like voyeurism, exhibitionism, masochism, sadism, pedophilia, and transvestism.  But the DSM has never included apotemnophilia as one of the paraphilic disorders. 

Money has a long list of over 30 paraphilias, which include asphyxiophilia (self-strangulation), autoassassinophilia (own murder staged), autonepiophilia (diaperism), narratophilia (erotic talk), and zoophilia (animals) (Money 1986, 441).

Money tried to explain apotemnophilia as caused by a psychological or psychiatric condition of unusual erotic obsession.  He noted that both of his cases were men, which was not surprising since all of the paraphilias occur predominantly in men.  He saw this desire for amputating a limb as related primarily to eroticization of the stump and secondarily to an erotic imagery of overachievement, in which visualizing an amputee surmounting a physical handicap became an erotic turn-on.

In the years following Money's article, psychologists followed Money's lead in looking for psychiatric/psychological causes for this disorder.  But then in 2005, Michael First moved this research in a different direction.  He interviewed 52 people who desired amputation (all but four were men).  The six who had obtained amputations reported that they were satisfied, because without the foreign limb they "felt complete" for the first time in their lives.

First noted that sexual arousal was only a secondary motivation for most of these people, and so he suggested that Money was wrong about this being a paraphilia.  The primary motivation seemed to be identity--the desire to "feel complete" in one's body without an alien limb.  To replace the term apotemnophilia, he proposed Body Integrity Identity Disorder (BIID), which would suggest the parallel to Gender Identity Disorder.  Others have proposed that a better term for this would be xenomelia ("foreign limb") (McGeoch et al. 2011).


NEUROLOGICAL EXPLANATIONS

Over the past 20 years, there has been a move away from psychological or psychiatric explanations of this disorder to neurological explanations.  Neuroscientists have pointed to the neural correlates of BIID, which indicate how this disorder is rooted in the brain.  But as is so often the case with research like this, correlation is not necessarily causation:  given the plasticity of the brain, we cannot be sure whether the neural correlates of BIID are the causes or the effects of the disorder.  Do abnormalities in the structure and functioning of the brain cause BIID?  Or does living with this disorder create these abnormalities in the brain?  Or do we need to see a complex interaction of multiple causes--mind, brain, and society?

The primary reason for believing that there must be neural correlates for BIID was that for over a hundred years neurologists had studied the loss of body ownership--mostly on the left side of the body--after damage to the right hemisphere of the brain, which suggested that the sense of bodily self-ownership is largely based in the right cerebral hemisphere.

For example, in 1914, the French neurologist Joseph Babinski introduced a new neurological term anosognosia, coined from three Greek words--a (without), nosos (disease), gnosis (knowledge)--for a disorder suffered by some patients with extensive damage to the right hemisphere of the brain: the left side of their body was paralyzed, but they were unaware, or seemed to be unaware, of this paralysis.  Later, this term was broadened to include a broad range of disorders in which people fail to recognize the presence or the severity of their neurological deficits from brain damage (Jenkinson 2014).

Anosognosia is now seen as one of a long list of bodily disorders (including BIID) in which some dimension of bodily awareness has been disrupted by an abnormality in the brain, often caused by damage from stroke to the right cerebral hemisphere of the brain (Case et al 2020).  A list of such neurological and psychiatric bodily disorders compiled by Frederique de Vignemont (2020, pp. 212-14) numbers over 50.

This list includes:

Autoprosopognosia.  Inability to recognize one's own face.

Cotard syndrome.  Delusional belief that one is dead, does not exist, is putrefying, or has lost one's blood or internal organs.

Delusional parasitosis.  Tactile hallucination associated with the delusion that small creatures are infesting one's skin.

Embodiment delusion.  Feeling another individual's left arm as being one's own.

Heutoscopy.  Seeing a double of oneself at a distance.

Negative heutoscopy.  Inability to see one's reflection in a reflecting surface.

Out of body experience.  Visual awareness of one's own body from a location outside the physical body.

Phantom limb.  Awareness of a non-existing limb, often after amputation.

Somatoparaphrenia.  Denial of ownership of one's own body part.

As de Vignemont notes, bodily disorders like this are not rare.  There is one report that over half of the stroke patients in a neurological department has some kind of impairment in bodily awareness (Denes 1990; Schwoebel and Coslett 2005).  If these disorders seem rare, it's because often they appear for only a few days or weeks and then disappear.

Since the most common pattern is damage to the right cerebral hemisphere causing bodily disorder in the left side of the body, those looking for the neural correlates of BIID have suspected that they are most likely to be found mostly in the right hemisphere.  And, indeed that seems to be the case.

One thorough examination through brain imaging of 15 males with a strong desire for amputation of one or both legs found predominantly right-sided cortical abnormalities in the parietal lobe and the right anterior insula (Berti 2013; Hilti et al. 2013).  A recent brain imaging study of 16 men desiring the amputation of the left healthy leg found structural and functional abnormalities in the target limb sensorimotor area and in the right superior parietal lobe (rSRL).  The greater the atrophy in the rSPL the stronger was the desire for amputation (Saetta et al. 2020).  

This suggests that the brain has evolved to have a neural network to establish and maintain a sense of body ownership, but that a disruption in this network can break down this normal bodily ownership in a way that inclines people to feel a desire for amputating healthy limbs that feel alien to them.

Neural abnormality might also explain the erotic connotations of BIID.  Although it is a speculative explanation, these erotic fantasies "may have their roots in the proximity of primary somatosensory cortex for leg representation, whose surface area was reduced in the participants with xenomelia, with that of the genitals."  Or "the spatial adjacency of secondary somatosensory cortex for leg representation and the anterior insula, the latter known to mediate sexual arousal beyond that induced by direct tactile stimulation of the genital area, might play a role" (Hilti et al. 2013, 318).  

Some of the same areas in the brain that are associated with the xenomelic/BIID disorder partially overlap with the brain areas that are damaged in the disorder known as somatoparaphrenia, in which people deny the ownership of their left legs or arms and often say these limbs belong to someone else.  While somatoparaphrenia is an acquired abnormality from severe lesions in the right hemisphere, xenomelia might arise from a congenital abnormality in the brain.  Even if there is some uncertainty as to whether the abnormal neurocircuitry of xenomelia is cause or effect, it is clear that the desire for amputating one's healthy limb is imprinted in one's brain.

In the next post, I will say more about somatoparaphrenia, and how it illuminates the neural basis of bodily ownership.


REFERENCES

Berti, Anna. 2013. "This Limb Is Mine But I Do Not Want It: From Anatomy to Body Ownership." Brain 136: 11-13.

Case, Laura K., Marco Solca, Olaf Blanke, and Nathan Faivre. 2020. "Disorders of Body Representation." In K. Sathian and V. S. Ramachandran, eds., Multisensosry Perception: From Laboratory to Clinic, 401-422. London: Academic Press.

Denes, Gianfranco. 1990. "Disorders of Body Awareness and Body Knowledge." In F. Boller and J. Grafman, eds., Handbook of Neuropsychology, 2: 207-228. Amsterdam: Elsevier.

First,  Michael. 2005. "Desire for the Amputation of a Limb: Paraphilia, Psychosis, or a New Type of Identity Disorder?"  Psychological Medicine 35: 19-28.

Hilti, Leonie Maria, Jurgen Hanggi, Deborah Vitacco, Bernd Kraemer, Antonella Palla, Roger Luechinger, Lutz Jancke, and Peter Brugger. 2013. "The Desire for Healthy Limb Amputation: Structural Brain Correlates and Clinical Features of Xenomelia." Brain 136: 318-329.

Jenkinson, Paul M., and Aikaterini Fotopoulou. 2014. "Understanding Babinski's Anosognosia: 100 Years Later." Cortex 61: 1-4.

McGeoch, Paul D., David Brang, Tao Song, Roland R. Lee, Mingxiong Huang, and V. S. Ramachandran. 2011. "Xenomelia: A New Right Parietal Lobe Syndrome." Journal of Neuroscience, Neurosurgery, and Psychiatry 82: 1314-1319.

Money, John. 1977. "Apotemnophia: Two Cases of Self-Demand Amputation as a Paraphilia." The Journal of Sex Research 13: 115-125.

Money, John. 1986. Venuses Penuses: Sexology, Sexosophy, and Exigency Theory. Buffalo, NY: Prometheus Books.Schwoebel, J., and H. B. Coslett. 2005. "Evidence for Multiple, Distinct Representations of the Human Body." Journal of Cognitive Neuroscience 17: 543-553.

Saetta, Gianluca, Jurgen Banggi, Martina Gandola, Laura Zapparoli, Gerardo Salvato, Manuela Berlingeri, Maurizio Sherna, Eraldo Paulesu, Cabriella Bottini, and Peter Brugger. 2020. "Neural Correlates of Body Integrity Disorder." Current Biology 30: 2191-2195.

Schwebel, J., and H. B. Coslett. 2005. "Evidence for Multiple, Distinct Representations of the Human Body." Journal of Cognitive Neuroscience 17: 543-553.

Sedda, Anna, and Gabriella Bottini. 2014. "Apotemnophia, Body Integrity Identity Disorder or Xenomelia? Psychiatric and Neurological Etiologies Face Each Other." Neuropsychiatric Disease and Treatment 10: 1255-1265.

de Vignemont, Frederique. 2020. Mind the Body: An Explanation of Bodily Self-Awareness.  Oxford: Oxford University Press.

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