Delirium.

The concept of delirium has been with us for over two thousand years.Greek physicians, such as Hippocrates, described its essential features' and the Roman writer Celsus distinguished it from mania and depression.2Galen differentiated between primary (idiopathic) and secondary (symptomatic) forms of the disorder.'Delirium is common in the hospital set- ting.4It often goes undiagnosed in its early stages5 and may therefore present as a neuro- logical emergency.If untreated, it is associa- ted with a high mortality.6The following article will therefore pay close attention to the diagnosis of the condition and its proper management.In addition, we will review its epidemiology, aetiology and pathogenesis.