Abstract

So there you are, in the emergency department, on a night shift. You have just seen a young woman with an unremarkable past medical history who had come to hospital because of an excruciating headache. The pain had come on in seconds, or at most two minutes, about three hours beforehand, while she was clearing the kitchen. Even though the examination was normal you have ordered a CT scan, as you are well aware that it can take 6 h or more for neck stiffness to develop after subarachnoid haemorrhage (SAH). To your surprise there is no evidence of subarachnoid blood or other abnormality on any of the CT slices; the radiology resident has the same opinion. Since you may now be feeling a little nonplussed, if only briefly, the next section is meant to help you get quickly back on your feet again.

IS THE CT SCAN REALLY NORMAL?