intracranial aneurysm

Introduction and aims: Traditionally, neurologically pristine patients with a thunderclap headache are investigated with a non-contrast computed tomography (CT) brain scan, which if negative is followed by a lumbar puncture (LP) to exclude important secondary causes, particularly subarachnoid haemorrhage (SAH). However, misdiagnosis of such patients is still a cause of significant human and financial cost and a regular reason for medical litigation.