13th August 2024

A 36-year-old male is seen in A&E. He reports experiencing a sudden, extremely severe headache

A 36-year-old male is seen in A&E. He reports experiencing a sudden, extremely severe headache whilst having sexual intercourse with his partner approximately 8 hours ago. The pain came on within a few seconds just before orgasm and then reduced in intensity over the following hours. These symptoms have occurred once in the past, 3 years ago. He is usually well and takes no regular medications. His full neurological examination is normal and there is no evidence of neck stiffness or photophobia. His BP is 130/80 mmHg in his right arm and 126/74 mmHg in his left arm. His observations are: HR 96 bpm, oxygen saturations 98% and temperature 36.9 degrees Celsius. He has normal heart sounds and a regular pulse with no radio-radial delay. You are concerned about the history and order the following investigations:


CT brain without contrast: normal appearances CT venogram brain: no abnormalities	CT angiogram of head and neck: No abnormalities

CT brain without contrast: normal appearances

CT venogram brain: no abnormalities

CT angiogram of head and neck: No abnormalities


Lumbar puncture opening pressure: 18 cmH₂O (5-20)	CSF WBC (white blood cells)/mm³: 6 (lymphocytes) (<5) CSF RBC/mm³: <1 (<5) CSF protein: 0.46 g/L (0.2-0.45)	CSF xanthochromia: negative CSF culture -ve (CSF = cerebrospinal fluid)

Lumbar puncture opening pressure: 18 cmH₂O (5-20)

CSF WBC (white blood cells)/mm³: 6 (lymphocytes) (<5)

CSF RBC/mm³: <1 (<5)

CSF protein: 0.46 g/L (0.2-0.45)

CSF xanthochromia: negative

CSF culture -ve

(CSF = cerebrospinal fluid)

What is the most likely diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.