Apr 16 2013

Body Integrity Identity Disorder

Imagine that one of your limbs did not feel as if it belonged to you or was a natural part of your body. In a weird way the “extra” limb makes you feel incomplete, less than your whole self. The limb functions, you can feel it, and its completely healthy – it’s just not yours. It is a constant irritant. Eventually you become obsessed with the idea of amputating the limb. You fantasize about amputation and imagine yourself without the offensive body part.

This desire to amputate a healthy limb was described and named apotemnophilia  by Money in 1977. It has recently been renamed Body Integrity Identity Disorder (BIID). This is a rare and interesting disorder – at first it was thought to be psychological, but it is more likely to be a neurological disorder.

Recent fMRI evidence suggests that people with BIID have decreased activation of their right superior parietal lobe when the “extra” limb is touched. This likely relates to the brain’s internal map or schema of the body.

We take for granted that we feel as if we occupy our bodies, that we own the various parts of our bodies, and that we control them, but each of these sensations is actively constructed by circuits in the brain. These circuits can be disrupted.

When those parts of the brain involved in the network that makes us feel as if we occupy our body are disrupted the result is an out-of-body experience. This active brain construction relies upon sensory information, which for sighted people is mostly visual, but also sensory. This fact can be exploited using virtual reality technology. Essentially a subject can view a virtual image of themselves being touched, while the corresponding body part is actually touched. This can trigger the brain to construct their physical location in the virtual image – they will feel as if they physically occupy their virtual self.

Control is a similar phenomenon. Circuits in the brain compare the intention to move a limb with the actual movement, monitored by sight and sensation (tactile and proprioception, which is the sense of where a body part is in three-dimensional space). When the intention to move and the actual movement match, the brain constructs the sensation that you control the relevant body part. If this circuit is disrupted the result is called alien-hand syndrome – sufferers feel as if they do not control a body part, which acts on its own as if it is under alien control.

Finally there can be a mismatch between the brain’s internal map of the body (through a network called the ownership module) and the body itself. This is most often seen with phantom limb syndrome – after losing a limb some people still feel its presence, because their brain is still mapping to the missing limb. There are also cases of supernumerary phantom limb, when stroke or other brain damage disconnects the ownership module from the paralyzed limb, and it temporarily creates an extra phantom limb to own.

Interestingly, although rare, congenital phantom limb syndrome has been described. This is very interesting for it raises the question (very relevant to BIID) of why someone’s brain would map to a limb that never existed. This is a bit of a controversy that has not yet been resolved.

The simplest explanation is that the brain’s body map is genetically determined and hard-wired. In other words – it is independent of the development of the body itself. This contradicts to some extent the notion that brain areas actively map to body parts during development, so-called somatotopic mapping, which requires sensory feedback from the body part. Without the sensory feedback, why would the brain allocate resources to a non-existent limb.

An alternate theory is that the brain does interactively map to the body, but it is not entirely dependent on internal sensation. The process may also involve seeing other people and mirror neurons mapping to the image of what people look like. Body image is therefore partly learned from experience.

Given this as background, BIID can be seen as fitting nicely into this set of disorders that represent a mismatch between the brain’s actively constructed model of self and the physical reality of self. In the case of BIID the body is whole but the brain’s map of it is missing a piece, so that body part does not feel like it belongs.

BIID is rare, and so we mostly have case reports to go on in understanding this disorder, with only preliminary fMRI studies. A review of published case reports does provide some useful information. They found among cases: low age of onset, male predominance, no preferred sexual orientation, an association with gender identity disorder, no pertinent family psychiatric history, no preferred side of the unwanted limb, association with exposure to an amputee at a young age, no history of trauma to the unwanted limb, frequent attempts at self-amputation, and association with certain personality disorders, such as borderline personality disorder.

In terms of treatment the reviewers found that selective serotonin reuptake inhibitors (SSRIs) and cognitive behavioral therapy (CBT) were sometimes effective in relieving the stress and depression associated with BIID, but they did not diminish BIID itself. The desire for amputation was unchanged. Further, in patients who did have the limb amputated, 70% had resolution of the desire for amputation, while 30% had a recurrence of the desire.

It is not yet clear what all this means, but there are some suggestions. Probably BIID is not one discrete disorder, but is the final result of several possible underlying causes that result in the brain-body mismatch.

The onset at young age and exposure to amputees is interesting, as these facts are compatible with the theory that body mapping occurs during young development and is partly due to experience. Perhaps, therefore, some people with BIID developed their internal body image based upon exposure to an amputee, and the missing limb therefore became the model of a whole body.  It’s also possible that exposure to the amputee was simply a trigger but the predisposition has to be present already.

Regardless of how it develops, it will likely prove difficult to “cure” BIID. We do not yet have the technology to alter the brain’s wiring in a way that would be necessary to change the internal body image. The brain does have plasticity (the ability to change its wiring), but this plasticity is limited. Some basic functions can only develop at a young age, and once the window of development closes the wiring cannot be changed.

Perhaps brain plasticity may be able to reduce or correct BIID, but I could not find any research even attempting such an intervention.

Current treatments focus on reducing the negative consequences of BIID rather than BIID itself, namely the distress and depression. This seems like a reasonable approach, and should at least be tried prior to amputating a healthy limb, an intervention with only a 70% success rate.

The ethics of amputating a healthy limb to treat BIID are unclear. It is not unreasonable, however, based upon the principle of autonomy, and it does appear to improve the quality of life in most BIID patients who have an amputation. But this should be considered a last resort, only after serious attempts at non-invasive treatment have been made.

It is time, however, for BIID to come out of the shadows. It should not be stigmatized. It is simply a neurological disorder. Even though we do not yet have anything close to a cure, it can be addressed medically.

 

 

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13 responses so far

13 Responses to “Body Integrity Identity Disorder”

  1. Ori Vandewalleon 16 Apr 2013 at 11:48 am

    I find it interesting that there’s a correlation with gender identity disorder. That could certainly just mean that individuals who are physically male but feel female naturally don’t feel as if their penis is their own, but I could imagine the reverse being the case.

    If for whatever reason your homonculus never mapped your genitalia correctly, then you may respond by taking body image cues from women. By the time you’ve developed your own self-image, you will feel female on the inside.

    (And I imagine all of this could be true for female to male transgenders as well.)

  2. jreon 16 Apr 2013 at 5:54 pm

    I was massively intrigued by Anil Ananthaswamy’s article in Matter, as I suppose anyone would be — the first time you hear about BIID it sounds more bizarre than anything you could have imagined.

    And I happened on that article by accident. Tom Levenson recommended another excellent article by Cynthia Graber, currently a fellow in Tom’s science journalism program. With those two articles, I was hooked. I subscribed to Matter, and have never regretted it.

  3. Dianeon 17 Apr 2013 at 7:45 am

    @Ori

    Funny; I, too, have wondered whether there might be some similarities between body integrity disorder and gender identity disorder. It would be nice if there were some way for people to get their gender identity (or mental image of their body) and their physical body into agreement without the use of surgery and hormones. But we are very far from figuring out what could be done, and in the meantime both people with BID and transgender people are likely to be very offended by the suggestion that their deeply-felt understanding of who they are is a manifestation of a neurological problem. So I would be surprised if much progress is made on this issue anytime soon.

  4. Ori Vandewalleon 17 Apr 2013 at 8:38 am

    Diane:

    I’m sympathetic to the fact that transgendered people don’t want to be labeled as neurologically wrong. I think it’s better to look at it from this point of view: a very large number of variables play into how our brains develop. Most of the time, those variables converge on a gender identity and physical sex that seem to coincide. Sometimes, they don’t. But what this means is that no matter what your mental image of yourself is, it’s dependent on your neurological development. All of what a human is can be deconsructed into something physical, but that doesn’t make it any less genuine; that’s just what genuine actually means.

    But if a person is unhappy with their identity for whatever reason, there should be resources available to help.

  5. HHCon 17 Apr 2013 at 5:30 pm

    Would not the amputation of a healthy limb in a person with BIID be considered fraud by a healthcare insurance provider?

  6. superdaveon 17 Apr 2013 at 6:46 pm

    What we really need to is to dissociate biologically uncommon with sociologically wrong.

  7. Marshallon 18 Apr 2013 at 11:27 am

    Steve, the link to your most recent blog post on Predicting the Future appears to be broken.

  8. Steven Novellaon 18 Apr 2013 at 11:58 am

    Thanks. Working now.

  9. HHCon 18 Apr 2013 at 9:17 pm

    If we have to use disassociation to accept this phenomenon, will vanity influence insurance economics?

  10. HHCon 19 Apr 2013 at 5:43 pm

    If persons with BIID in the U.S.A. pay out of pocket over $20,000 for amputation, do they attempt to recover their intentional disability from our social security system?

  11. daedalus2uon 22 Apr 2013 at 9:47 pm

    The connections of sensory nerves to the brain pretty much have to be learned. There simply isn’t enough data in the genome to specify each connection.

  12. postmanon 06 May 2013 at 8:57 am

    @Diane:

    Are you saying that changing the wiring of the brain would be less invasive than a simple surgery or hormone therapy? Yes, I would be offended in their place, too.

    I think that even if such therapies are available , it should be the individual’s choice how to deal with their situation.

  13. tashiegirlon 27 Jul 2013 at 1:57 am

    Hi, I think i might have an interesting case of BIID. I’m totally congenitally blind, but my homonculus is sighted, or as sighted as it can be, given that I can’t see with my physical eyes. I find the mismatch between my brain and body to be quite strange, and I’m working on trying to develop a way to experience color with my fingertips so that I can feel more myself.

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