The investigation of acute severe headache suggestive of probable subarachnoid haemorrhage: a hospital-based study.

We reviewed the diagnostic approach to patients presenting with headache suggestive of subarachnoid haemorrhage (SAH) and normal cranial imaging, both locally and using a questionnaire, in other units throughout the United Kingdom. We emphasize the correct timing of cranial imaging and lumbar puncture (LP), the importance of proceeding to LP and utilizing spectrophotometry in patients with normal cranial imaging, and the appropriate use of angiography.