LP question

[Blondbondgirl]

---

Members do not see this ad.

So I don't quite understand the whole LP contraindication with increased ICP for three reasons:
1- It is indicated (relative indication, blah blah blah) for SAH!?
2- People lose all CSF during spinal surgery and they're fine!? (after a couple of days on their backs, but whatever)
3- Draining off CSF can be therapeutic!

So... what exactly is the danger!? The only thing I find in books is the list of contraindications and relative contraindications...😕

Thanks!

 

[SoCuteMD]

They can have an uncal or transtentorial herniation. Uncal herniation = death.

 

[EternalMD]

herniation = death.

Just had to agree with and emphasize the above statement.

 

[strv04]

since when has death been a contraindication

 

[obiwan]

I read that you don't do LP if patient presents with symptoms of ICP in addition to meningial signs... however, isn't headache common to both presentations?

 

[SoCuteMD]

I read that you don't do LP if patient presents with symptoms of ICP in addition to meningial signs... however, isn't headache common to both presentations?

If an adult has any symptoms of ICP, they get a CT first. In fact, pretty much every adult that gets an LP gets a CT first. The same applies to children with closed fontanelles.

 

[Blondbondgirl]

Thanks for your help-

but I still don't understand why death is risked for SAH and therapeutic LPs! Can't that happen then, too?

 

[SoCuteMD]

Thanks for your help-

but I still don't understand why death is risked for SAH and therapeutic LPs! Can't that happen then, too?

Patients ALWAYS get a CT to rule out increased ICP before they get an LP for SAH - hence a much much much lower risk of herniation (I won't say 0, as we all know it's never 0). As for therapeutic LPs - these patients have also had a CT and they do have increased ICP but it's due to underabsorption of CSF (at least that's the hypothesis, I think they don't know for sure). They take off a controlled amount of CSF in these patients to avoid herniation. My guess would be that you'd have a hard time finding someone willing to tap a patient with suspected idiopathic intracranial hypertension. It would get done eventually, but would probably fall to neurology.

 

[KidDr]

If an adult has any symptoms of ICP, they get a CT first. In fact, pretty much every adult that gets an LP gets a CT first. The same applies to children with closed fontanelles.

Just a correction--in evaluating for meningitis or encephalitis, there is rarely an indication to do a head CT prior to performing an LP in kids with closed fontanelles. The main exceptions to this would be a kid with an abnormal neuro exam, or a kid who presented with a focal seizure.

In terms of doing an LP for reasons other than looking for intracranial infection in kids with closed fontanelles, the main indications I can think of (excluding medically complex hospitalized kids who undergo LP for lots of reasons) are:
--benign intracranial hypertension (pseudotumor cerebri), which is a diagnosis of exclusion (and the diagnosis is also based on ophthalmologic exam), and these kids have almost invariably already undergone head CT as part of their diagnostic workup.
--as part of the work up of afebrile seizures in young children; usually these kids have already undergone intracranial imaging

Just wanted to clarify that, because in peds we do a ton of LPs w/o doing head CTs---in the adult world it's usually the opposite. In my experience and in talking with my adult EM colleagues, they usually do a head CT prior to doing an LP.

 

[Blondbondgirl]

Thanks a latte!