- Clinical science
Delirium is a neurocognitive disorder characterized by impaired attention, awareness (reduced orientation to the environment), and other disturbed cognitive functions (e.g., memory, language, or perception). Symptoms develop acutely and tend to fluctuate throughout the day. Delirium occurs as a direct physiological consequence of another medical condition. It is most often a complication of polypharmacy, especially in elderly patients, and is also commonly seen in patients admitted to the ICU. Although delirium is a reversible confusional state, it warrants urgent medical attention because it may be the first sign of serious underlying disease. Treatment of delirium focuses on treating the underlying illness and reducing exposure to exacerbating factors. Antipsychotic medications are used for the treatment of agitation in delirious patients.
- The exact mechanism responsible for delirium is unknown. 
- Pediatric, elderly (> 65 years), and hospitalized patients are particularly susceptible.
- Typically secondary to:
- Metabolic diseases (most common cause; also referred to as metabolic encephalopathy)
- Infection such as UTIs (most common cause in elderly patients), pneumonia, meningitis
- Trauma (e.g., hip fracture, head injury)
- CNS pathology (e.g., stroke, brain tumor)
- Hypoxia (e.g., anemia, cardiac failure, COPD, pulmonary embolism)
- Acute cardiovascular disease (MI, shock, vasculitis)
Drugs and toxins (also referred to as toxic encephalopathy)
- Benzodiazepines, barbiturates
- Antidepressants and antipsychotics (especially those with anticholinergic activity, e.g., quetiapine)
- Antihistamines (particularly in elderly patients)
- Diuretics (may cause electrolyte abnormalities)
- Recreational drugs (intoxication/withdrawal)
- Alcohol use disorder and alcohol withdrawal
- Heavy metals (e.g., arsenic, lead, mercury)
- Sleep deprivation
- Major surgery
- Hearing or vision loss
- Ongoing symptoms, including:
I WATCH DEATH: Infection, Withdrawal, Acute metabolic disorder, Trauma, CNS pathology, Hypoxia, Deficiencies, Endocrine, Acute vascular, Toxins/drugs, and Heavy metals are the major causes of delirium.
- The main symptom is an acute (hours to days) alteration in the level of awareness and attention.
- Other features may include:
- The severity of symptoms fluctuates throughout the day and worsens in the evening (termed sundowning).
- Symptoms are reversible; their duration and severity depend on the underlying illness.
- Delirium is commonly described based on the type of alteration that is seen:
|Psychomotor activity||Patient groups|
|Mixed type delirium||Fluctuates or stays at baseline||Most common type in the general population|
|Hypoactive delirium||Decreased||Most common type in the elderly population|
|Hyperactive delirium||Increased (agitation)||Usually seen in delirium due to substance use or substance withdrawal|
- If the cause of delirium is not obvious based on the patient history and physical findings:
- Start with complete blood count, serum glucose, electrolytes, and urinalysis.
- If medication or substance use is suspected: urine toxicology or serum drug levels
- If a metabolic etiology is suspected: serum creatinine, BUN, liver function tests, arterial blood gas
- If pneumonia is suspected: chest x-ray
- If a cardiac etiology (e.g., myocardial infarction, arrhythmia) is suspected: ECG
- If the patient has focal neurological deficits or the initial workup is negative, further tests may include:
- Further diagnostics that may be considered include:
In older patients, it is important to differentiate delirium from dementia.
|Delirium vs. dementia|
|Onset|| || |
|Course|| || |
|Level of consciousness|| || |
|Attention|| || |
|Memory|| || |
|Thought process|| || |
|Hallucinations|| || |
|Psychomotor activity|| || |
|EEG|| || |
|Reversibility|| || |
The differential diagnoses listed here are not exhaustive.
- Identify and treat the underlying cause (e.g., discontinue causative medications such as anticholinergics)
- Supportive medical care
- Manage agitation initially with nonpharmacologic strategies (see “Prevention” below).
- Administer antipsychotics if the patient is agitated and/or poses harm to themselves or others.
- Initiate cognitive stimulation therapy to improve cognitive function.
- Reduce pain, preferably with nonopioid medications.
- Prevent aspiration, incontinence, and skin breakdown.
Benzodiazepines are deliriogenic. Do not treat delirious patients with benzodiazepines unless the delirium is due to alcohol or benzodiazepine withdrawal, in which case haloperidol is contraindicated because it lowers the seizure threshold!
- Reduce exposure to modifiable risk factors.
Reorient the patient regularly.
- Keep a clock and/or calendar near the patient to help with orientation.
- Provide visual and hearing aids for patients with impairments.
- Reduce the amount of noise, procedures, and medication administration occurring at night.; (because delirium more frequently occurs and worsens at night, uninterrupted sleep is important for both prevention and management of delirium)
- Arrange for regular visits from family and friends.
- Arrange for constant observation, preferably by a family member or friend.
- Provide physical and occupational therapy to mobilize the patient as soon as possible.
- Minimize the use of physical restraints as much as possible.
- Pharmacologic