1. Subarachnoid hemorrhage diagnosis-what to do J. Stephen Huff, MD Fourth-Year student elective director Professor of Emergency Medicine and Neurology University of Virginia Virginia College of Emergency Physicians Hot Springs, Virginia 2016 Corey Heitz, MD Director, Undergraduate Medical Education Assistant Professor of Emergency Medicine Virginia Tech Carilion

2. Disclosures none

3. Objectives Rule out SAH without performing an LP every time!

4. What are we looking for? Aneursymal SAH or Non-aneurysmal SAH

5. Aneurysmal SAH High morbidity and mortality Possibility of “sentinel bleeding”

6. Non-aneurysmal SAH Aka perimesencephalic SAH Usually venous Minimal long term effects

7. Point #1: We aren’t just looking for blood, we are looking for aneurysmal bleeding

8. Testing algorithm POSITIVE: NO LP NEGATIVE, LP POSITIVE NEGATIVE, LP NEGATIVE CT angio done

9. Proposed revision POSITIVE NEGATIVE* CT Angio (CTA) DONE Angio (CTA)

10. Let’s talk about LP Invasive Sometimes painful Complications Doesn’t diagnose aneurysm!

11. But if it’s a good test… 2 true positives in 302 patients ~1 in 200 after negative head CT

12. Risk/Benefit NND: 150-200 NNH: 10-20

13. Point #2: LPs are low yield, high adverse effects

14. But is CT good enough? Perry et al 2011: 953 patients CTed within 6 hours: all SAHs diagnosed Backes et al 2012: validated sens/spec of 100%

15. But is CT good enough? Dubosh 2016 8907 patients 13 missed SAH on CT 1.46 per 1000 CTs LR- for CT: 0.010 (0.003-0.034) NND for LP: 700

16. Proposed revision POSITIVE NEGATIVE* CT Angio (CTA) DONE Angio (CTA)

17. Proposed revision POSITIVE NEGATIVE* CT Angio (CTA) DONE Angio (CTA)

18. Proposed revision POSITIVE NEGATIVE* CT Angio (CTA) DONE Angio (CTA)

19. Proposed revision POSITIVE NEGATIVE* CT Angio (CTA) DONE Angio (CTA)

20. Summary LPs are low yield and fair # of complications CT within 6 hours is excellent Positives go to angio anyway 700 LPs to diagnose 1 missed bleed? Insane