New Tool Identifies Headache Patients at Risk of Aneurysm

A new study tests a tool that identifies potentially fatal aneurysms in emergency department (ED) patients with headaches who seem otherwise well.

The Ottawa Subarachnoid Hemorrhage Rule, developed at the University of Ottawa (Canada), Université Laval (Canada), and other institutions, requires that an investigation for subarachnoid hemorrhage (SAH) be initiated if one or more of the following symptoms is presented by the patient: neck pain or stiffness; age over 40 years; witnessed loss of consciousness; onset during exertion; thunderclap headache (i.e., peak pain instantly); and limited neck flexion upon examination. To validate the rule, the researchers conducted a multicenter prospective cohort study at six EDs in Canada from January 2010 to January 2014.

The study included 1,153 alert, neurologically intact adult patients with a headache peaking within one hour of onset, of which 67 were found to be suffering from SAH. The results revealed that the Ottawa SAH Rule showed 100% sensitivity and a specificity of 13.6%, whereas neuroimaging identification rates were similar to previous studies, at about 87%. The researchers therefore suggest that the validated rule could help identify high-risk patients, rule out SAH in low-risk patients, and limit ED imaging needs. The study was published on November 13, 2017, in the Canadian Medical Association Journal (CMAJ).

“Although rare, accounting for only 1-3% of headaches, these brain aneurysms are deadly. Almost half of all patients with this condition die, and about two out of five survivors have permanent neurological deficits,” said lead author Jeffrey Perry MD, MSc, of the University of Ottawa. “Patients diagnosed when they are alert and with only a headache have much better outcomes, but can be challenging to diagnose as they often look relatively well.”

“Before any clinical decision rule can be used safely, it must be validated in new patients to ensure that the derived 'rule' did not come to be by chance, and that it is truly safe. This is especially true with a potentially life-threatening condition such as subarachnoid hemorrhage,” concluded Dr. Perry. “We estimate that this rule could save 25 lives in Ontario each year. We hope this tool will be widely adopted in emergency departments to identify patients at high risk of aneurysm, while cutting wait times and avoiding unnecessary testing for low-risk patients.”

SAH is defined as detection of any of the following findings: subarachnoid blood visible upon computed tomography (CT) of the head; xanthochromia in the cerebrospinal fluid (CSF) by visual inspection; or the presence of erythrocytes (> 1 × 106/L) in the final tube of CSF, with an aneurysm or an arteriovenous malformation visible upon cerebral angiography.

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University of Ottawa
Université Laval