Any guideline that gives priority to the prompt identification of patients at risk of brain injury deserves to be supported and timely imaging (CT brain scan or skull radiograph, or both) is an essential part of this process. Recently published guidelines recognise the increased availability of emergency CT in the UK.^1–3 The Scottish Intercollegiate Guidelines Network Publication number 46 (August 2000) recommends the increased use of CT brain scans for selected patients with mild head injury including those with the radiological demonstration of a skull fracture.²

The National Institute for Clinical Excellence: Clinical Guideline (2003)³ includes an adapted form of The Canadian CT head rules,⁴ which lowers the threshold for scanning patients with mild head injury much further and relies very little on the use of skull radiographs.

A concern is whether such guidelines can be safely and effectively implemented if hospitals in the UK lack the necessary resources for easy access to out of hours CT.

The Canadian CT head rules were …