Diagnostic Workup of Acute Headache and Subarachnoid Hemorrhage in a Norwegian Population: an Observational Study

BackgroundAcute headache may be the primary symptom of subarachnoid hemorrhage (SAH). Recent guidelines suggest that non-contrast computed tomography (CT) is adequate to exclude aneurysmal SAH if performed within 6 h after symptom onset. However, most studies of acute headache including CT, lumbar puncture and SAH are multicenter studies from referral hospitals with highly selected patient populations. The main purpose of this study was to describe the diagnostic properties of head CT and cerebrospinal fluid (CSF) spectrophotometry for detecting SAH in an unselected primary hospital population with acute headache.MethodsA retrospective cross-sectional study conducted at a large primary hospital serving roughly 10% of the Norwegian population. Diagnostic workup from consecutive patients evaluated for acute headache in 2009-2020 were collected. All CSF-spectrophotometry reports were standardized and the same CT scanner was used during the study.ResultsA total of 3227 patients were included. Median age was 45 years and 63% were women. In total, 170 (5.3% of all acute headache patients) had SAH. Of 3071 CT-negative patients, 2852 (93%) underwent lumbar puncture. Of the CSF reports, 2796 (98%) were negative for xanthochromia. Overall, the rate for detection of aneurysmal SAH by positive xanthochromia was 9 in 2852 cases (3 parts per thousand). The miss rate for the detection of an aneurysmal SAH with a CT scan within 6 h was 0 and within 12 h 1 in 2852 cases (0.3 parts per thousand).ConclusionIn acute headache, a CT scan taken within 6 h in 100% sensitive for detecting any SAH.