Delirium is an acute neuropsychiatric syndrome characterized by a sudden onset of disturbances in attention, awareness, and cognition, often accompanied by restlessness, agitation, disorientation, and perceptual disturbances such as hallucinations or illusions.

• The condition typically develops rapidly over hours to days and is usually reversible if the underlying cause is identified and treated.

• Delirium commonly occurs in older adults, critically ill patients, and those with metabolic, infectious, or toxic insults.

Pathophysiology

The pathophysiology of delirium is multifactorial and incompletely understood but involves:

• Neurotransmitter imbalances:

  • Decreased acetylcholine contributes to impaired attention and memory.

  • Dopamine excess may lead to agitation and hallucinations.

• Inflammatory processes:

  • Cytokine release in infections or systemic illness disrupts neuronal signaling.

• Metabolic and endocrine disturbances:

  • Electrolyte imbalances, hypoglycemia, or thyroid dysfunction impair neuronal function.

• Structural or functional CNS impairment:

  • Trauma, hemorrhage, or seizures may trigger acute cognitive changes.

These mechanisms lead to dysregulated cortical and subcortical networks, producing the hallmark features of delirium.

Examination Technique

Patient Observation

• Assess level of consciousness (fluctuating alertness).

• Observe attention and orientation to time, place, and person.

• Note psychomotor activity: hypoactive, hyperactive, or mixed.

• Watch for hallucinations, illusions, and emotional lability.

Structured Assessment

• Confusion Assessment Method (CAM): Validated tool for rapid delirium detection.

• Mini-Mental State Examination (MMSE) or bedside cognitive tests may help quantify cognitive deficits.

• Vital signs and general examination: Identify systemic causes (fever, hypotension, hypoxia).

Clinical features

Differential Diagnosis

Pediatric considerations

• Less common but may occur with infections, high fever, hypoxia, or medication effects.

• Presentation may include irritability, inconsolable crying, or unusual sleep-wake patterns.

Geriatric considerations

• Older adults are highly susceptible due to polypharmacy, sensory deficits, and baseline cognitive impairment.

• Delirium in elderly patients often predisposes to prolonged hospitalization, falls, and functional decline.

Limitations

• Fluctuating nature may cause under-recognition, especially in hypoactive delirium.

• Requires careful collateral history from caregivers or staff.

• Screening tools (e.g., CAM) are supportive, not diagnostic; clinical judgment is essential.

Patient counseling

• Explain that delirium is usually reversible once the underlying cause is treated.

• Emphasize monitoring and safety, particularly in older adults.

• Educate caregivers to report sudden behavioral changes, confusion, or agitation promptly.

Management

Identification and Correction of Underlying Cause

• Review medications, correct metabolic disturbances, treat infections, and manage pain.

Supportive Care

• Ensure hydration, nutrition, oxygenation, and safe environment.

• Minimize sensory deprivation; provide reorientation cues.

Symptomatic Management

• Low-dose antipsychotics (e.g., haloperidol) for severe agitation or psychosis, only if necessary.

• Avoid benzodiazepines except in alcohol or sedative withdrawal.

Conclusion

Delirium is an acute, reversible neuropsychiatric syndrome marked by confusion, agitation, and perceptual disturbances. Prompt recognition and treatment of underlying causes are essential to prevent complications and improve outcomes, especially in vulnerable populations such as the elderly and critically ill.

References

1. Inouye SK. Delirium in older persons. N Engl J Med. 2006;354:1157–1165.

2. American Psychiatric Association. DSM-5: Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: APA; 2013.

3. Han JH, et al. Delirium in the elderly: epidemiology, pathophysiology, and management. Clin Geriatr Med. 2012;28:575–601.

4. Marcantonio ER. Delirium in hospitalized older adults. N Engl J Med. 2017;377:1456–1466.

5. Ely EW, et al. Delirium in mechanically ventilated patients: validity and reliability of the Confusion Assessment Method for the ICU (CAM-ICU). JAMA. 2001;286:2703–2710.