This is Steve Carroll, and you're listening to EM Basic Essential Evidence. Today we'll be talking

about a paper that has some people changing their practice when it comes to working up subarachnoid

hemorrhage, while others have said, well, not so fast. The big question is, do we still need to

do a lumbar puncture in these patients? Today we'll talk about a paper that answers that question

with a maybe.

As always, this podcast doesn't represent the views or opinions of the Department of Defense,

the U.S. Army, or the Fort Hood Post Command. The title of this article is

sensitivity of computed tomography performed within six hours of onset of headache

for diagnosis of subarachnoid hemorrhage, prospective cohort study.

It was published in the British Medical Journal on July 18, 2011.

The first author is Jeffrey Perry, and a second author is the well-known Canadian EM researcher Ian Steele.

So let's talk about the background for this article.

In a patient with suspected subarachnoin

hemorrhage, the current standard of care is to perform a non-contrast head CT

followed by a lumbart puncture if the head CT is negative. With the resolution of CT

scanners increasing year by year, the question is, do we still have to do a lumbar puncture

if the CT is negative?

So let's talk about the study design.

So this was a prospective cohort study.

A cohort is just a way of saying a group of patients that share something in common.

In this study, a sudden onset of an acute headache.

The prospective nature of it means that the data was collected in a looking

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