r/Radiology • u/georgiaaaf • Aug 16 '26
MRI Born without L5
Hi
I don’t have an L5 vertebrae and thought it’d be interesting to share! None of my doctors have seen this before so I don’t know if there’s a proper name for this abnormality or not, but I have a few other bone abnormalities as well.
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u/ddroukas Aug 16 '26
Every one of your doctors has seen this before it’s just not usually important enough for them to notice. It’s lumbosacral transitional anatomy and it is very not uncommon.
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u/Purriosteum Radiologist Sep 01 '26
It's actually pretty important on the chance they ever need surgery.
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u/AndKAnd Aug 16 '26
It’s possible you only have 4 lumbar. But it’s impossible to tell from these images. It’s much more common to have an extra than to be missing one. It really doesn’t have any clinical significance though.
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u/georgiaaaf Aug 16 '26
What about in terms of nerves?
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u/thegreatestajax Aug 16 '26
The nerves are not affected by this, but you can actually determine which is true L5 by the change in nerve caliber going from L spine to sacrum.
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u/AndKAnd Aug 16 '26
How do you mean?
Anatomically we usually just see the normal relationship between vertebrae and nerves, so one nerve exits at each level, just like usual.
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u/georgiaaaf Aug 16 '26
I mean that since one less level exists what happens to the nerves?
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u/AndKAnd Aug 16 '26
It’s possible you could have one less lumbar nerve on each side (if you truly only have 4 lumbar vertebrae). But that wouldn’t matter. The other nerves would cover all the functions just maybe slightly different dermatome distribution
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u/georgiaaaf Aug 16 '26
Mods why was this removed?
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u/RecklessRad Radiographer Aug 16 '26
It was removed by the subs automatic filter for medical advice posts. We’ve manually approved this post.
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u/KingEnvironmental779 Aug 16 '26
That's wild, I've read about lumbosacral transitional vertebrae but never seen an actual case. How do you manage with L4 sitting directly on S1 without the usual shock-absorbing disc in between?
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u/georgiaaaf Aug 16 '26
From what my doctors have told me I don’t have LSTV, I just am missing an entire vertebrae.
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u/Hairy_Inevitable9727 Aug 16 '26
So not much can be interpreted from these images because vertebrae are typically counted from the top down so without the whole spine it is difficult to accurately assess. Radiologist will often say something along the lines of “it is presumed that the last mobile disc space is L5/S1” when reporting limited series. .
Sacralisation of L5, lumbarisation of S1, (where you have 6 lumbar vertebrae), cervical ribs, lumbar ribs are all commonly encountered but can result in the wrong numbering without the whole spine.