Brain Aneurysms Are Effectively Identified By New Tool
The Ottawa Subarachnoid Hemorrhage (SAH) rule effectively identifies subarachnoid hemorrhage in patients with acute headache, according to a recent study.
Previously, the researchers derived the Ottawa SAH Rule to identify subarachnoid hemorrhage among patients presenting with an acute headache at emergency departments (EDs). To validate this rule, the researchers conducted a prospective cohort study at 6 EDs in Canada from January 2010 to January 2014. Using the SAH rule, ED staff scored adults presenting with a headache that peaked within 1 hour after onset who were alert and neurologically intact. Then the staff would investigate the cause of the headache using computed tomography or a spinal tap.
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The researchers defined subarachnoid hemorrhage as visible subarachnoid blood in computed tomography of the head, xanthochromia in the cerebrospinal fluid, or the presence of erythrocytes in the final tube of cerebrospinal fluid, with an aneurysm or arteriovenous malformation visible on cerebral angiography.
Of the 1153 patients enrolled in the study, 67 had subarachnoid hemorrhage.
Overall, the Ottawa SAH rule had a 100% sensitivity and a 13.6% specificity compared with neuroimaging rates, which were at about 87%.
“We found that the Ottawa SAH Rule was sensitive for identifying subarachnoid hemorrhage in otherwise alert and neurologically intact patients,” the researchers concluded. “We believe that the Ottawa SAH Rule can be used to rule out this serious diagnosis, thereby decreasing the number of cases missed while constraining rates of neuroimaging.”
—Melissa Weiss
Reference:
Perry JJ, Sivilotti MLA, Sutherland J, et al. Validation of the Ottawa subarachnoid hemorrhage rule in patients with acute headache [published online November 13, 2017]. CMAJ. doi:10.1503/cmaj.170072.