28th May 2025

A 45-year-old woman with no past medical history presents to A&E with a sudden onset of a severe occipital headache with pain radiating down to her neck.

A 45-year-old woman with no past medical history presents to A&E with a sudden onset of a severe occipital headache with pain radiating down to her neck. There is no history of preceding trauma. Her initial non-contrast CT brain is normal, and she goes on to have a lumbar puncture which is positive for xanthochromia.

Which of the following options is the correct next investigation?