Investigations Summary

At present, evidence and opinion dictate that all patients presenting with acute severe headache <2 weeks from the index episode should undergo non-contrast CT scanning of the brain.

If this is reported as normal (ideally by a neuroradiologist) then an LP should be undertaken at least 12 hours from the start of the headache.” to “If this CT scan is completed within 6 hours of onset of symptoms, and reported by a radiologist, then further investigation should not be routinely offered. If the scan is more than 6 hours from the onset of symptoms, an LP should be undertaken at least 12 hours from the start of the headache.