High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study

The print (“pico”) version (and its associated pdf) of this research paper by Jeffrey J Perry and colleagues (BMJ 2010;341,c5204, doi:10.1136/bmj.c5204) erroneously suggests that lumbar puncture precedes computed tomography, which could be dangerous. The first sentence of the section headed, “What is known and what this paper adds” is wrong: “It is currently recommended that all emergency patients with abrupt onset headache undergo lumbar puncture followed by computed tomography to exclude subarachnoid haemorrhage.” The full (online) version of the paper is correct and states, “Patients with suspected subarachnoid haemorrhage are typically investigated with unenhanced computed tomography and a lumbar puncture if the scan result is negative.”