An unusual case of spontaneous subarachnoid haemorrhage - a ruptured aneurysm of a basilar perforator artery.

A 51-year-old gentleman with no significant past medical history presented with a WFNS grade 1 subarachnoid haemorrhage. Initial angiographic investigations revealed no cause, but repeat tests showed a small basilar perforator aneurysm. Following a failed attempt at endovascular treatment, a craniotomy and excision of the aneurysm was performed. Post-operatively the patient made a good recovery. This case highlights the importance of delayed repeat catheter angiography in selected patients with suspicious initial CT head results.