Delirium is sudden severe confusion and rapid changes in brain function that occur with physical or mental illness.

Acute confusional state; Acute brain syndrome

Delirium is most often caused by physical or mental illness and is usually temporary and reversible. Many disorders cause delirium, including conditions that deprive the brain of oxygen or other substances.

Causes include:

• Alcohol or sedative drug withdrawal
• Drug abuse
• Electrolyte or other body chemical disturbances
• Infections such as urinary tract infections or pneumonia (more likely in people who already have brain damage from stroke or dementia)
• Poisons
• Surgery

Delirium involves a quick change between mental states (for example, from lethargy to agitation and back to lethargy).

Symptoms include:

• Changes in alertness (usually more alert in the morning, less alert at night)
• Changes in feeling (sensation) and perception
• Changes in level of consciousness or awareness
• Changes in movement (for example, may be slow moving or hyperactive)
• Changes in sleep patterns, drowsiness
• Confusion (disorientation) about time or place
• Decrease in short-term memory and recall
  • Unable to remember events since delirium began (anterograde amnesia)
  • Unable to remember events before delirium (retrograde amnesia)
• Disrupted or wandering attention
  • Inability to think or behave with purpose
  • Problems concentrating
• Disorganized thinking
  • Speech that doesn't make sense (incoherent)
  • Inability to stop speech patterns or behaviors
• Emotional or personality changes
  • Anger
  • Agitation
  • Anxiety
  • Apathy
  • Depression
  • Euphoria
  • Irritability
• Incontinence
• Movements triggered by changes in the nervous system (psychomotor restlessness)

The following tests may have abnormal results:

• An exam of the nervous system (neurologic examination), including tests of feeling (sensation), thinking (cognitive function), and motor function
• Neuropsychological studies

The following tests may also be done:

• Ammonia levels in the blood
• Blood chemistry (comprehensive metabolic panel)
• Blood gas analysis
• Chest x-ray
• Cerebrospinal fluid (CSF) analysis
• Creatine kinaselevel in blood
• Drug, alcohol levels (toxicology screen)
• Electroencephalogram(EEG)
• Head CT scan
• Head MRI scan
• Liver function tests
• Mental status test
• Serum magnesium
• Thyroid function tests
• Urinalysis
• Vitamin B1 and B12 levels

The goal of treatment is to control or reverse the cause of the symptoms. Treatment depends on the condition causing delirium. Diagnosis and care should take place in a pleasant, comfortable, nonthreatening, physically safe environment. The person may need to stay in the hospital for a short time.

Stopping or changing medications that worsen confusion, or that are not necessary, may improve mental function significantly. Medications that may worsen confusion include:

• Alcohol
• Analgesics, especially narcotics such as codeine, hydrocodone, morphine, or oxycodone
• Anticholinergics
• Central nervous system depressants
• Cimetidine
• Illicit drugs
• Lidocaine

Disorders that contribute to confusion should be treated. These may include:

• Anemia
• Decreased oxygen (hypoxia)
• Heart failure
• High carbon dioxide levels (hypercapnia)
• Infections
• Kidney failure
• Liver failure
• Nutritional disorders
• Psychiatric conditions (such as depression)
• Thyroid disorders

Treating medical and mental disorders often greatly improves mental function.

Medications may be needed to control aggressive or agitated behaviors. These are usually started at very low doses and adjusted as needed.

Medications include:

• Antidepresssants (fluoxetine, citalopram), if depression is present
• Dopamineblockers (haloperidol, quetiapine, or risperidone are most commonly used)
• Sedatives (clonazepam or diazepam) in cases of delirium due to alcohol or sedative withdrawal
• Thiamine

Some people with delirium may benefit from hearing aids, glasses, or cataract surgery.

Other treatments that may be helpful:

• Behavior modification to control unacceptable or dangerous behaviors
• Reality orientation to reduce disorientation

Acute conditions that cause delirium may occur with chronic disorders that cause dementia. Acute brain syndromes may be reversible by treating the cause.

Delirium often lasts only about 1 week, although it may take several weeks for mental function to return to normal levels. Full recovery is common.

• Loss of ability to function or care for self
• Loss of ability to interact
• Progression to stupor or coma
• Side effects of medications used to treat the disorder

Call your health care provider if there is a rapid change in mental status.

Treating the conditions that cause delirium can reduce its risk. In hospitalized patients, avoiding sedatives, staying still (immobilization), and bladder catheters, and using reality orientation programs will reduce the risk of delirium in those at high risk.

Inouye Sk. Delirium and other mental status problems in the older patient. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 26.