Supplementary material online:
The translated German full-text version of this article is available at SpringerLink (under supplemental dx.doi.org/10.1007/s10049-015-0040-x).
This paper describes using the rule of 4 of the brainstem to help emergency physicians readily identify patients with brainstem problems. It is a simple set of four rules that demystify the brainstem. It is not designed to discuss patients presenting with coma, of which brainstem problems are only one of the many causes. It will also discuss cerebellar infarction and haemorrhage, because although not strictly part of the rule of 4, these are medical emergencies that can, at times, easily be missed.