Sudden headache, third nerve palsy and visual deficit: thinking outside the subarachnoid haemorrhage box

A 75-year-old lady presented with sudden severe headache and vomiting. Examination was normal, and CT and lumbar puncture not convincing for subarachnoid haemorrhage. Shortly thereafter, she developed painless diplopia. Examination confirmed right third cranial nerve palsy plus homonymous left inferior quadrantanopia. Urgent cerebral MRI with angiography was requested to assess for a possible posterior communicating artery aneurysm, but revealed an unsuspected pituitary mass. Pituitary adenoma with pituitary apoplexy was diagnosed. Pituitary apopolexy is a syndrome comprising sudden headache, meningism, visual and/or oculomotor deficits, with an intrasellar mass. It is commonly due to haemorrhage or infarction within a pituitary adenoma. Treatment includes prompt steroid administration, and potentially surgical decompression. While subarachnoid haemorrhage is an important, well-recognised cause of sudden severe headache, other aetiologies, including pituitary apoplexy, should be considered and sought.