Thoughts from the darkroom…

One of the commonest requests for out of hours imaging is for cranial CT in patients with possible meningitis. Telephone conversations like this may be familiar: "Hello I’m the medical SHO on call….I’d like to request a CT brain please…to rule out raised intracranial pressure before lumbar puncture…no we couldn’t get a good look at his fundi….they didn’t have any tropicamide in A and E…well, perhaps you’d like to do the LP if you don’t think a CT is necessary…" This type of request in fact may or may not be justified depending on the clinical scenario. The perception of radiologists is that few patients with possible meningitis require head CT before lumbar puncture; the perception of physicians is that the majority do. Pole-positions like this invariably generate conflict between our specialities. Can we use the available literature to guide us to a more evidence-based approach which both groups will find acceptable ?