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Stroke. 2012 Aug;43(8):2115-9. doi: 10.1161/STROKEAHA.112.658880. Epub 2012 Jul 19.

Time-dependent test characteristics of head computed tomography in patients suspected of nontraumatic subarachnoid hemorrhage.

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Department of Neurology and Neurosurgery, UMC Utrecht Stroke Center, Utrecht, The Netherlands.



A recent study suggested that in patients with acute headache suspicious of nontraumatic subarachnoid hemorrhage (SAH), cerebrospinal fluid (CSF) analysis is not needed to rule out SAH if head CT performed ≤6 hours after ictus is negative. Before implementation in daily practice, these results need replication. Therefore, we investigated test characteristics of head CT in patients with a clinical suspicion of SAH.


Patients suspicious of SAH and a normal level of consciousness presenting to our tertiary care hospital between 2005 and 2012 were included. All patients had a head CT interpreted by experienced neuroradiologists and CSF spectrophotometry if head CT was negative or inconclusive. We determined test characteristics with 95% confidence intervals (CI) for nontraumatic SAH of head CT performed ≤6 or >6 hours after onset of headache.


Sensitivity of head CT ≤6 hours after ictus (n=137) was 98.5% (95% CI, 92.1%-100%), diagnosing all patients with aneurysmal and perimesencephalic SAH, but not with a cervical arteriovenous malformation. Sensitivity of head CT performed >6 hours after ictus (n=113) was 90.0% (95% CI, 76.3-97.2). After exclusion of patients with an atypical presentation without headache, sensitivity, specificity, negative predictive value, and positive predictive value of head CT ≤6 hours were all 100%.


In patients presenting with acute headache and a normal head CT ≤6 hours after ictus, as interpreted by experienced neuroradiologists, there is no added value of CSF analysis. In patients with an atypical presentation without headache and in patients presenting >6 hours after ictus, CSF analysis is still indicated.

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