Delirium

Definition
A condition of severe confusion and rapid changes in brain function, usually the result of treatable physical or mental illness. It may also be referred to as acute confusional state or acute brain syndrome.
Delirium involves a rapid alternation between mental states (for example, from lethargy to agitation and back to lethargy), with attention disruption, disorganized thinking, disorientation, changes in sensation and perception and other symptoms.
Symptoms
Attention disturbance
Inability to maintain goal-directed thinking
Inability to concentrate
Disorganized thinking
Incoherent speech
Inability to stop speech patterns or behaviors
Disorientation to time or place
Changes in sensation and perception
Illusions or hallucinations
Altered level of consciousness or awareness
Altered sleep patterns, drowsiness
Alertness may vary
Decrease in short-term memory and recall
Unable to recollect events since the onset of delirium or past events
Changes in motor activities, movement
Movements triggered by changes in the nervous system
Anxiety
Anger
Apathy
Depression
Euphoria
Irritability
Complications
Inability to function or care for self
Loss of ability to interact
Stupor or coma
Side effects from the medications used to treat the disorder
Other complications vary, depending on the causative disorder
Causes
Acute confusional states are usually the result of a physical or mental illness and are usually temporary and reversible.
Disorders that cause delirium are numerous and varied. They may include conditions that deprive the brain of oxygen or other substances. Delirium may be caused by diseases of body systems other than the brain, by poisons, by fluid/electrolyte or acid/base disturbances and by other serious, acute conditions.
Neurologic examination may reveal abnormalities, including atypical reflexes and unusual levels of normal reflexes. Psychologic studies and tests of sensation, cognitive function and motor function may be abnormal.
Treatment
The goal of treatment is to control or reverse symptoms. Treatment varies with the specific condition causing delirium. The person should be in a pleasant, comfortable, nonthreatening, physically safe environment for diagnosis and initial treatment. Hospitalization may be required for a short time.
The cause should be identified and treated.
Stopping or changing medications that worsen confusion, or that are not essential to the care of the person, may improve cognitive functioning even before treatment of the underlying disorder. Medications that may exacerbate confusion include anticholinergics, analgesics, cimetidine, central nervous system depressants, lidocaine and other medications.
Disorders that contribute to confusion should be treated. These may include heart failure, decreased oxygen (hypoxia), excessive carbon dioxide levels (hypercapnia), thyroid disorders, anemia, nutritional disorders, infections, kidney failure, liver failure and psychiatric conditions such as depression. Correction of coexisting medical and psychiatric disorders often greatly improves mental functioning.
Medications may be required to control aggressive or agitated behaviors that are dangerous to the person or to others. These are usually given in very low doses, with adjustment as required.
Medications that may be considered for use include:
Thiamine, sedating medications such as clonazepam or diazepam, serotonin-affecting drugs (trazodone, buspirone), dopamine blockers (such as haloperidol, olanzapine, risperidol, clozapine) and fluoxetine, imipramine, celexa (may help stabilize mood).
Formal psychiatric treatment may be necessary. Behavior modification might be helpful for some people to control unacceptable or dangerous behaviors. This consists of rewarding appropriate or positive behaviors and ignoring inappropriate behaviors (within the bounds of safety). Reality orientation, with repeated reinforcement of environmental and other cues, may help reduce disorientation.
Acute disorders that cause delirium may coexist with chronic disorders that cause dementia. Acute brain syndromes are potentially reversible with treatment of the underlying cause. Delirium often lasts only about one week, although it may take several weeks for cognitive function to return to normal levels. Full recovery is common.
Source: National Institutes of Health