Sudden headache, lumbar puncture, and the diagnosis of subarachnoid hemorrhage in patients with a normal computed tomography scans

Objective. To assess the usefulness of computed tomography (CT) to identify subarachnoid bleeding in patients with neurologic deficits seeking emergency care for sudden headache within 6 hours of onset of symptoms. Methods. Retrospective observational study of patients presenting with sudden nontraumatic headache peaking during the previous hour in the absence of neurologic deficits. We ordered CT scans for all patients, and if the scan was normal we performed a lumbar puncture. All patients were then followed for 6 months. Results. Eighty-five patients were included. Subarachnoid bleeding was identified in 10 (10.2%) patients by CT. Seventy-four lumbar punctures were performed in patients with negative CTs; the lumbar puncture was positive in 1 patient and inconclusive in 2 patients. In all 3 patients, bleeding was ruled out with later images; thus, no cases of subarachnoid hemorrhage were confirmed in the 74 patients who underwent lumbar puncture. Nor were any cases found in any of these patients during follow-up. Conclusions. A CT scan taken within 6 hours of onset of sudden headache is sufficient for confirming or ruling out subarachnoid bleeding in patients with sudden headache who have no neurologic deficits.