I was born as 'situs inversus totalis'. I'm right-handed. Does that mean I am really left-handed? Does that mean that my Broca's area is on the right side?

Asked by virtualist (2452

) September 26th, 2009

I was born with my internal organs , spatially, a mirror image of ‘normal’ .. .like holding a mirror to yourself. Everything functions totally normally.

I have asked this question , regarding whether there are other ‘functional’ inversions, of many of my medical colleagues .. and they do not know. I’ve wondered whether fMRI or PET scan could answer these questions… I think the answer is yes but these expensive imaging procedures cannot be ‘prescribed’ and reimbursed, just to satisfy my curiosity.

The incidence for ‘SIV’ is ~1:10,000 and the highest worldwide incidence is in Greenland. There is one complicating syndrome which can accompany this SIV and which I fortunately do not have… it involves the cilia of the lungs and sperm ducts, e.g. not functioning properly…. all proving rather lethal.

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6 Answers

I believe that situs inversus is limited to the viscera, so I think your brain is probably normative.

dpworkin (27090

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According to eMedicine it is indeed limited to the organs of the chest and abdomen. The fact that yours is ‘totalis’ means that your heart is also reversed, just like Dr. No in the James Bond book of the same title. Your brain is not affected by it.

Darwin (21877

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There was a 1999 study (“Structural and functional brain asymmetries in human situs inversus totalis”) that performed fMRIs on three subjects with situs inversus totalis. It found that while there was a reversal of the frontal and occipital petalia (asymmetries in the fore and aft distribution of volume between the two hemispheres), all of the subjects still showed left hemisphere language dominance, as well as strong right-handedness. The study concludes that the genetic factors for situs invertus appear to determine the petalia, but that the determining factors for language laterality are separate.

Harp (19179

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Harp…... so where, exactly, does the anti-asymmetry of ‘function’ occur, given the successful asymmetry of ‘form’ induced by SIV ?? ....thanks…..

virtualist (2452

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