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Suspected subarachnoid hemorrhage — ABIM Board MCQ

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HardNeurologySuspected subarachnoid hemorrhageABIM Board

A 49-year-old woman has a thunderclap headache and neck stiffness. Noncontrast head CT performed 10 hours after onset is negative. Neurologic examination is normal, eGFR is 18 mL/min/1.73 m² and she previously had anaphylaxis to iodinated contrast. Which study should be obtained next?

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Correct answer: A — Perform lumbar puncture for red cells and xanthochromia assessment

The best answer is “Perform lumbar puncture for red cells and xanthochromia assessment”. CT sensitivity for subarachnoid blood declines when imaging occurs more than six hours after onset. Additional evaluation is required. Lumbar puncture is the appropriate next study here because both severe kidney disease and prior contrast anaphylaxis make CT angiography unattractive; red-cell pattern and xanthochromia aid interpretation.

Reference: 2023 AHA/ASA Guideline for Aneurysmal Subarachnoid Hemorrhage: https://pubmed.ncbi.nlm.nih.gov/37212182/