Delirium

Delirium refers to an acute impairment in attention that compromises cognitive function; it is often associated with fluctuating arousal. Attention can be easily assessed at the bedside by asking the patient to perform “serial 7s” (subtract 7 from 100 and then repetitively subtracting 7 from each new total) or to repeat a series of numbers forward and then backward. The delirious patient may have periods of seeming lucidity followed by profound agitation and confusion. Hallucinations and combative behavior are common. Delirium is one of the most frequent neurologic conditions encountered in hospitalized patients, and is particularly common in the elderly. Medications commonly used for delirium are presented in Table 10.1 (contained in Appendix 1).

A.

Numerous underlying conditions predispose to delirium. The most common risk factors are advanced age, infection, dementia, immobility, electrolyte imbalance, malnutrition, and urinary catheterization. A careful search for underlying causes and reversible risk factors should be undertaken in all patients with delirium. Diagnostic testing should be tailored to the specific clinical scenario, but commonly includes a serum chemistry panel and complete blood count, urinalysis, urine and blood cultures, chest radiography, and toxicology screening. The presence of focal neurologic findings on examination should prompt urgent brain imaging. Electroencephalography and lumbar puncture may be necessary in some cases.
B.

In all patients with delirium, a focus on nonpharmacological measures is critical. These include redirection, promoting a normal sleep-wake cycle, removal of unnecessary lines, drains, or catheters, and transfer to a quiet environment whenever possible.
C.

Drug intoxication and alcohol withdrawal can mimic delirium. In stimulant intoxication and alcohol withdrawal, patients often have tachycardia, hypertension, diaphoresis, and tremor. Opiate intoxication is usually accompanied by bradycardia, hypotension, hypoventilation, and miosis. Prompt, specific treatment, especially for alcohol withdrawal and opiate overdose, can be life-saving.
D.

Alcohol withdrawal is treated with symptom-driven benzodiazepine administration, often using a prespecified protocol such as the Clinical Institute Withdrawal Assessment for Alcohol Scale (CIWA-Ar) to quantify symptom severity and guide dosing. (See the CIWA-Ar protocol in the Appendix.) Patients with severe withdrawal symptoms may require intensive care management. Patients with delirium related to either alcohol intoxication or withdrawal should receive intravenous thiamine as the risk of concomitant thiamine deficiency and thus Wernicke encephalopathy is increased. A typical starting dose is 500 mg IV tid.
E.

Delirium may be subdivided into hyperactive, hypoactive, and mixed types. Hyperactive delirium occurs when cognitive impairment is accompanied by agitation and increased motor and speech output, whereas hypoactive delirium is associated with lethargy and decreased motor and speech output. Most patients demonstrate a mixed delirium type. Hypoactive delirium should be treated with nonpharmacological measures alone. For hyperactive and mixed delirium, antipsychotics such as haloperidol are typically used. Atypical antipsychotics or valproic acid should be used if there is a high risk for electrocardiographic QT interval prolongation or for patients at high risk of extrapyramidal side effects (i.e., comorbid Parkinsonism).