Delirium

What it is

Delirium is a transient disturbance of consciousness with marked impairment in attention that develops over hours to days and waxes and wanes with time. Acute confusional state is an old term for delirium. It is a medical condition that requires urgent intervention.

Causes and risk

Being elderly and being an inpatient are the risk factors named. Hospitalized patients, particularly those recovering from brain injuries, burns, or cardiac procedures, are especially susceptible to episodes of delirium. Delirium also turns up as a feature of particular conditions:

• Heat stroke, where a core body temperature above 40°C (104°F) comes with central nervous system dysfunction: slurred speech, irritability, inappropriate behavior, agitation, ataxia and other signs of poor coordination, altered mentation, delirium, seizures, and coma.
• Thyroid storm, where the mental status runs through agitation, delirium, psychosis and, late, coma, with hyperthermia often above 40°C and tachycardia.
• Alcohol withdrawal, as delirium tremens.
• Hepatic encephalopathy, which can present as an acute confusional state.

One worked case sets the risk factors out. A patient who is febrile and less responsive needs to be evaluated medically, because these symptoms highly suggest delirium; and what put him at risk were his age, a two years history of forgetfulness, and medical comorbidities.

Read the three together: the fever is the insult, the two years of forgetfulness are the brain it fell on, and the comorbidities are the rest. None of the three on its own is the diagnosis, and all three named as risk factors is why the first move is to evaluate him medically.