Interesting study in Annals this month: Sensitivity of Noncontrast Cranial CT for the ED Diagnosis of SAH Anyone hoping that imaging will save us from the annoying CT/LP paradigm for working up suspected SAH is out of luck. This study shows that CT alone is just as insensitive for SAH (missing ~7%) as we always thought. The real problem is that the CT/LP mantra translates to having to do a lot of LPs, an invasive, painful procedure that is sometimes technically difficult, often time consuming and have several significant complications. The reason is that anyone who describes their headache as the worst theyve ever had or as sudden onset is under suspicion of SAH even though thats a huge population of those who come to the ED for headache. Theres an interesting editorial attached to the article by Clifton Callaway (that you can only get if youre an Annals subscriber. He brings up a few really interesting points: - Future imaging technology my help but not anytime real soon. - It may not be necessary to rule out tiny amounts of blood from non-treatable lesions. This is analogous to the If you cant see the PE with the CT chest its too small to worry about argument. - We need a better definition of the low risk patient for SAH. This last point is the most interesting to me. Is there a way we can identify patients who are low risk enough to skip the LP? We need a NEXUS style tool for this clinical entity. I smell research project! Lastly, some good news. Perry, et. al. studied the CT/LP regimen and found that it is sensitive enough to effectively rule out SAH. Thank goodness for that. Is the Combination of Neg CT and Neg LP Sufficient to RO SAH?