PL para hemorragia subaracnoidea
LP for Subarachnoid Hemorrhage: The 700 Club
Is it worth 700 LPs to find one aneurysmal subarachnoid hemorrhage?
By David H Newman, MD. on December 4, 2012
"The literature on this topic is both fresh and remarkably good. The studies are recent, large and prospective, with excellent follow-up. And the results are straightforward. It turns out that following classic dogma means performing roughly 700 lumbar punctures for every one aneurysmal subarachnoid hemorrhage detected...
There’s more. The 700 calculation presumes that patients undergoing LP have acute onset, first time, mostly worst-of-life headaches. In relevant studies roughly 8-10% of such patients have a subarachnoid hemorrhage, making this a high risk group. But that’s not most headache patients. In patients with half the risk, the ratio of LPs to aneurysmal SAH jumps from 700 to 1400. And for those with lower risk headaches the number is in the thousands, which helps to explain why finding an aneurysmal SAH by LP is a Ghostbusters moment...
This is a revelation. According to our best calculations, unless a patient has high risk headache features (syncope, stiff neck, etc.) the most beneficial approach to diagnosing SAH is a CT scan—with no LP—because the scan typically gets you well under the 1% mark..."
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