Health Encyclopedia

Delirium

Definition

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

Alternative Names

Acute confusional state; Acute brain syndrome

Causes, incidence, and risk factors

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:

Drug abuse
Infections such as urinary tract infections or pneumonia (in people who already have brain damage from stroke or dementia)
Poisons
Fluid/electrolyte or acid/base disturbances

Patients with more severe brain injuries are more likely to get delirium from another illness.

Symptoms

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 inactive or slow moving)
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 past events (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
- Anxiety
- Apathy
- Depression
- Euphoria
- Irritability
Movements triggered by changes in the nervous system (psychomotor restlessness)

Signs and tests

The following tests may have abnormal results:

An exam of the nervous system (neurologic examination)
Psychologic studies
Tests of feeling (sensation), thinking (cognitive function), and motor function

The following tests may also be done:

Ammonia levels
B12 level
Blood chemistry (chem-20)
Blood gas analysis
Chest x-ray
Cerebrospinal fluid (CSF) analysis
CPK
Drug, alcohol levels (toxicology screen)
Electroencephalogram (EEG)
Glucose test
Head CT scan
Head MRI scan
Liver function tests
Mental status test
Serum calcium
Serum electrolytes
Serum magnesium
Thyroid function tests
Thyroid stimulating hormone level
Urinalysis

Treatment

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. Medications that may worsen confusion include:

Alcohol and illegal drugs
Analgesics
Anticholinergics
Central nervous system depressants
Cimetidine
Lidocaine

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

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

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:

Dopamine blockers (haloperidol, olanzapine, risperidone, clozapine)
Mood stabilizers (fluoxetine, imipramine, citalopram)
Sedating medications (clonazepam or diazepam)
Serotonin-affecting drugs (trazodone, buspirone)
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

Expectations (prognosis)

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.

Complications

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

Calling your health care provider

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

Prevention

Treating the conditions that cause delirium can reduce its risk.

Review Date:2/13/2008
Reviewed By:Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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