How does a LP cause herniation with increased ICP?

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I have googled and gotten nowhere. I see an increased ICP is a contraindication for a LP d/t risk of herniation. But how would the LP cause herniation?

Thanks!

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My classmates and I were pondering this the other day! We figured it was because :

1. the pressure is the same throughout the brain and spinal cord, inside and out.

2. you are relieving pressure on the outisde of the brain, down low.

3. The pressure from the ventricles can't equalize that fast, and since the spinal cord now has less pressure than the brain, that's where the pressure inside the brain goes.

How does that sound? Just our theory!

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Simply put......things will follow the path of lesser resistance. The brain is packed in tight getting tighter and tighter pressing the sides and you poke a whole in it......wooosh! Think finger in the dam or a tightly filled water balloon that is poked with a big pin!

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Simply put......things will follow the path of lesser resistance. The brain is packed in tight getting tighter and tighter pressing the sides and you poke a whole in it......wooosh! Think finger in the dam or a tightly filled water balloon that is poked with a big pin!

Year, that what we thought. The problem is that I don't think you get herniation with a ventriculostomy, which is done from the top o' the head. But I might be wrong.

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Let's also realize that people love to get caught up in the drama of LP's killing people from herniation, when in fact it's not exactly a common occurrence.

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Specializes in Hospice.

Although I have seen it ... once in 38 years at the bedside.

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I had read it was very rare, but a contraindication none-the-less. Thanks for the answer, it makes sense :)

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Lots of things are rare. Doesn't make them any less important to know, as well as the mechanism. I don't get the hate directed toward understand how something works.

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Specializes in Hospice.

Over the years, I have learned that if badness can happen, it eventually will. Best to have the info and not need it than to need it and not have it.

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I searched:

"Neurology Why is lumbar puncture contraindicated with increased intracranial pressure?"

Found abstracts... found an interesting one discussing Peds/meningitis/LP, and some others as well. I don't think anyone is a hater of knowledge, it's just that it's a procedure that has from what I read in the opinion of some to have been over-catastrophized - some think not. You'd have to agree it warrants concern.

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Lots of things are rare. Doesn't make them any less important to know, as well as the mechanism. I don't get the hate directed toward understand how something works.

No hate, I just want to place emphasis on the fact that this is rare and even debatable in some circles. Sometimes these rare things can take off and become scarecrows like the hypoxic drive.

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Specializes in ER.

Rare but potential exist regardless. As a provider I would never consider doing a LP on anyone with increased ICP, the evidence does not support performing the procedure and therefore would be negligent on my part to do so. The outcome is death and the reason that it's rare may be reflected by the fact that increased ICP is a contraindication in performing LP's.

On a side note, not sure what you mean by the Hypoxic drive scarecrow thing. I assume your talking about COPD pts and O2 use but may be wrong.

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