Delirium

Delirium is a serious and often undetected neuropsychiatric syndrome. Failure to recognize and manage delirium can lead to longer hospital stays and increased morbidity and mortality, especially among the elderly.

This article reviews definitions and diagnosis. The Diagnostic and Statistical Manual of Mental Disorders, 4th edition, and the International Statistical Classification of Diseases and Related Health Problems, 10th edition, criteria are quite similar in their diagnostic criteria. Risk factors include advanced age, preexisting brain disease or cognitive impairment, multiple medications, and severe medical problems. Delirium in the elderly can be more subtle and recovery more prolonged. Diagnosis is more complex if there is already an underlying dementia. An organized approach should be used to discover etiology and in ordering appropriate laboratory studies. At the cellular level, delirium is considered to be a reversible disregulation of neuronal membrane function. This involves a selective vulnerability of certain populations of neurons and neurotransmitter dysfunction. Practical treatment issues are reviewed.

Despite advances, delirium is usually still diagnosed at the bedside. Having an organized approach to diagnosis and understanding the underlying pathophysiology should help with overall evaluation and treatment.