A New Clinical Decision Rule for Subarachnoid Hemorrhage

In patients with acute headache, detection of subarachnoid hemorrhage (SAH) is important because ruptured aneurysm is the most common cause and is amenable to surgical repair. Investigators prospectively assessed the accuracy of several decision rules for SAH in a cohort of 2131 patients who had nontraumatic headache that peaked within 1 hour and normal neurologic examination findings at 10 academic urban Canadian emergency departments.

SAH was diagnosed in 132 patients (6.2%), although 35 patients (0.02%) were lost to follow-up. The final decision rule called for specific investigation of patients with any of the following characteristics: age ≥40, neck pain or stiffness, limited neck flexion, witnessed loss of consciousness, onset during e…