A clinical approach to diagnosing encephalopathy

Encephalopathy refers to dysfunction of the level and/or contents of consciousness due to brain dysfunction and can result from global brain insults or focal lesions. The underlying causes of encephalopathy include both primary neurologic and systemic conditions. This article discusses the differential diagnosis of encephalopathy, with a focus on primary neurologic causes. A practical schema for organizing the differential diagnosis is to group etiologies by their pace of onset and evolution (e.g., sudden, acute, subacute, chronic).