R.E.B.E.L.EM - Posted by Salim Rezaie
"Background: The traditional standard workup for ruling out subarachnoid hemorrhage (SAH) has been a non-contrast head CT and, if negative, a lumbar puncture. The thought behind this is that the sensitivity of head CT to rule out SAH is not 100% and declines over time and missing a SAH is potentially devastating. There has been a series of studies published in the past few years looking at the value of a negative head CT scan performed within 6 hours of headache onset in ruling out SAH. I have heard many say that if they have a negative Head CT at 6 hours or less in a neurologically intact patient they would not perform a lumbar puncture.
What Trials are we Reviewing?
- Perry JJ et al. Sensitivity of Computed Tomography Performed Within Six Hours of Onset of Headache for Diagnosis of Subarachnoid Haemorrhage: Prospective Cohort Study. BMJ 2011; 343: d4277. PMID: 21768192
- Backes D et al. Time-Dependent Test Characteristics of Head Computed Tomography in Patients Suspected of Nontraumatic Subarachnoid Hemorrhage. Stroke 2012; 43(8): 2115 – 9. PMID: 22821609
- Blok KM et al. CT Within 6 Hours of Headache Onset to Rule Out Subarachnoid Hemorrhage in NonAcademic Hospitals. Neurology 2015; 84(19): 1927 – 32. PMID: 25862794
Clinical Take Home Point: In patients with a history consistent with SAH, normal mental status, no focal neurologic deficits, and a negative head CT performed within 6 hours, a shared decision strategy should be used as this is not a 100% sensitive strategy, but should also be balanced with the risk of complications such as post LP headache and false positive testing."