Diagnosis of subarachnoid hemorrhage in the emergency department

Headaches are nearly ubiquitous; patients with this complaint account for 1% to 2% of all emergency department (ED) visits. Approximately 1% of all patients presenting to an ED with headache have subarachnoid hemorrhage (SAH), where failure to or delay in diagnosis may lead to significant morbidity and mortality. Despite the widespread availability of neuroimaging equipment, misdiagnosis remains surprisingly common, occurring in 23% to 53% of patients with SAH on their first physician consultation. There are three generic causes for the misdiagnosis rate: failure to appreciate the spectrum of clinical presentation, failure to understand the limitations of computed tomography, and failure to perform and correctly interpret the results of lumbar puncture. This article identifies which patients should be evaluated for SAH and how the work-up should proceed. Improvements in these areas would likely reduce the frequency of misdiagnosis.