Confusion. Agitation. Irritability. A wander around any emergency department or neurology ward will yield an abundance of observations that can fall under these categories and yet these are not all due to long waiting times or general hospital mayhem. All these symptoms are common presentations of neurological dysfunction and they are features of that syndrome that neurologists call encephalopathy, which refers to a state of altered consciousness that is typically accompanied by changes in cognition or perception. Working out why someone has encephalopathy is challenging and can take time. While some diagnoses are easier to pick, such as systemic infection, in other cases symptoms can be so non-specific that finding a unifying diagnosis can be very hard despite the wonders of modern medical technology.

In this month’s issue of JNNP, Sutter and Kaplan have published an outstanding review that addresses neuroimaging in acute encephalopathy http://jnnp.bmj.com/content/86/4/446.abstract . Their paper provides an excellent outline of changes in MRI and CT which occur in various conditions that result in encephalopathy. They have gone through common and even rare causes of encephalopathy, indulging those related to immune and infectious mechanisms, and have complied useful lists of specific changes in brain areas that are characteristically involved in each condition.

This review will prove to be a very useful resource, for neurologists, emergency specialists and general physicians, all of whom will be called upon to manage these patients at one time or another.