Best evidence topic report. Timing of lumbar puncture in suspected subarachnoid haemorrhage.

A short cut review was carried out to establish how long after onset of headache a lumbar puncture should be carried out to rule out subarachnoid haemorrhage. Altogether 142 papers were found using the reported search, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this best paper are tabulated. A clinical bottom line is stated.