Subarachnoid haemorrhage — SCE Neurology MCQ

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HardHeadacheSubarachnoid haemorrhageSCE Neurology

A patient has an exertional thunderclap headache with neck stiffness. Non-contrast CT performed 10 hours after onset is normal and there is no contraindication to lumbar puncture. What is the next diagnostic step for suspected subarachnoid haemorrhage?

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Correct answer: E — Lumbar puncture after 12 hours for CSF bilirubin spectrophotometry

The best answer is “Lumbar puncture after 12 hours for CSF bilirubin spectrophotometry”. When CT is performed more than six hours after onset and remains negative despite clinical suspicion, NICE recommends considering lumbar puncture; waiting until at least 12 hours permits bilirubin formation for reliable spectrophotometry. “Outpatient observation after a delayed negative non-contrast CT” is less appropriate because CT sensitivity declines with time and does not always end evaluation after six hours “Serum D-dimer testing as a definitive haemorrhage exclusion test” is less appropriate because D-dimer cannot rule out aneurysmal subarachnoid bleeding “Carotid Doppler assessment as the primary vascular investigation” is less appropriate because carotid ultrasound does not examine the subarachnoid space or intracranial aneurysm “Routine brain MRI after a prolonged symptom-surveillance interval” is less appropriate because delayed outpatient imaging is unsafe after a high-risk thunderclap presentation

Reference: NICE NG228: Subarachnoid haemorrhage caused by a ruptured aneurysm. https://www.nice.org.uk/guidance/ng228/chapter/Recommendations