Epidemiology
Etiology
- A transient syndrome of acute brain dysfunction, not a specific disease.
- Results from a wide range of underlying medical conditions, substance intoxication/withdrawal, or medications.
- Key Pathophysiology: Believed to involve widespread disturbances in brain metabolism, neurotransmitter function (especially ↓ acetylcholine, ↑ dopamine), and inflammation.
Risk factors
- Advanced age
- Neurologic disorder (e.g. dementia, stroke)
- Sensory impairment (e.g. hearing loss)
- Sleep disruption
- Immobilization
Precipitating causes
- Drugs (eg, narcotics, sedatives, antihistamines, muscle relaxers, polypharmacy)
- Infections (eg, pneumonia, urinary tract infection, meningitis)
- Electrolyte disturbances (eg, hyponatremia, hypercalcemia)
- Metabolic derangements (eg, volume depletion, vitamin B12 deficiency, hyperglycemia)
- Systemic illnesses (eg, congestive heart failure, hepatic failure, malignancy)
- CNS conditions (eg, seizure, stroke, head injury, subdural hematoma)
Pathophysiology
Clinical features
- Acute onset (hours to days) and a fluctuating course are hallmarks.
- Core feature: Disturbance in attention and awareness.
- Associated features include disorganized thinking, altered sleep-wake cycle, perceptual disturbances (visual hallucinations are common), and psychomotor changes.
- Can be hyperactive (agitation), hypoactive (lethargy, more common and often missed), or mixed.
- Typically occurs in elderly, hospitalized, or post-operative patients, especially those with pre-existing cognitive impairment like dementia.
Diagnostics
- Differential diagnostics
- Mania: cognition is intact; not disoriented; treated with lithium
Treatment
- Polypharmacy/psychoactive drug avoidance
- Sleep facilitation: bright day/dim night lighting
- Visual/hearing aids
- Mobilization: out of bed, restraint avoidance
Treatment of agitation in delirium
- Agitation should initially be managed with nonpharmacologic strategies.
- Avoid physical restraints as much as possible in older patients with delirium, as they can worsen distress and agitation, as well as contribute to preventable injuries.
- Pharmacotherapy
- Antipsychotics
- Typical antipsychotics: e.g., haloperidol (most commonly used)
- Atypical antipsychotic options
- Risperidone
- Olanzapine
- Antipsychotics
Warning
- Avoid antipsychotics in patients with underlying alcohol withdrawal or benzodiazepine withdrawal (due to the risk of seizures) and in patients at high risk for QTc prolongation (due to the risk of torsades de pointes).
- Benzodiazepines are deliriogenic. Do not treat delirious patients with benzodiazepines unless the delirium is due to alcohol or benzodiazepine withdrawal.