Delirium

Delirium - What is Delirium?

Delirium (acute confusional state) is a common and severe neuropsychiatric syndrome with core features of acute onset and fluctuating course, attentional deficits and generalized severe disorganization of behavior.

It typically involves other cognitive deficits, changes in arousal (hyperactive, hypoactive, or mixed), perceptual deficits, altered sleep-wake cycle, and psychotic features such as hallucinations and delusions.

It is often caused by a disease process 'outside' the brain, such as common forms of infection (UTI, pneumonia) or by drug effects, particularly anticholinergic or other CNS depressants (benzodiazapenes and opioids). It can also be caused by virtually any primary disease of the central nervous system.

Though hallucinations and delusions are sometimes present, these are not required for the diagnosis, and the symptoms of delirium are clinically distinct from those induced by psychosis or hallucinogens.

Although commonly referred to as a primary disorder of attention, other core cognitive processes are disrupted, particularly working memory and virtually all aspects of executive functions (planning and organization of behavior).

Although it is commonly regarded as reversible, induction of delirium in patients with dementia due to Alzheimer's disease appears to accelerate cognitive decline, suggesting that efforts to prevent and minimize the induction of confusional states in the elderly should be given high priority.

Unfortunately, many instances of confusional state (delirium) are iatrogenic (caused by medicines or hospital-borne pathogens/bacteria or surgeries and anesthesia).

In medical usage it is not synonymous with drowsiness, and may occur without it. Delirium is not the same as dementia (the two entities have different diagnostic criteria), though it commonly occurs in demented patients.

Delirium may be of a hyperactive variety manifested by 'positive' symptoms of agitation or combativeness, or it may be of a hypoactive variety (often referred to as 'quiet' delirium) manifested by 'negative' symptoms such as inability to converse or focus attention or follow commands.

While the common non-medical view of a delirious patient is one who is hallucinating, most people who are medically delirious do not have either hallucinations or delusions.

Delirium is commonly associated with a disturbance of consciousness (e.g., reduced clarity of awareness of the environment). The change in cognition (memory deficit, disorientation, language disturbance) or the development of a perceptual disturbance, must be one that is not better accounted for by a pre-existing, established, or evolving dementia. Usually the rapidly fluctuating time course of delirium is used to help in the latter distinction.

Delirium itself is not a disease, but rather a clinical syndrome (a set of symptoms), which result from an underlying disease or new problem with mentation. Like its components (inability to focus attention, mental confusion and various impairments in awareness and temporal and spatial orientation), delirium is simply the common symptomatic manifestation of early brain or mental dysfunction (for any reason).

Without careful assessment, delirium can easily be confused with a number of psychiatric disorders because many of the signs and symptoms are conditions present in dementia, depression, and psychosis.

Delirium is probably the single most common acute disorder affecting adults in general hospitals. It affects 10-20% of all hospitalized adults, and 30-40% of elderly hospitalized patients and up to 80% of ICU patients.

Treatment of delirium requires treatment of the underlying causes. In some cases, temporary or palliative or symptomatic treatments are used to comfort patients or to allow better patient management (for example, a patient who, without understanding, is trying to pull out a ventilation tube that is required for survival).

Educational information is available for medical and non-medical persons with videos, management protocols, links to references, lectures, recent evidence from studies, implementation packets for hospitals, and even comments to families and loved ones for those witnessing someone going through a delirious episode.

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Delirium Causes

The highest prevalence of delirium (often 50% to 75% of patients) is generally seen in critically ill patients in the intensive care unit or ICU (which used to be referred to by the misnomer ICU Psychosis, a term largely abandoned now for the more widely accepted and scientifically supported term delirium).

Since the advent of validated and easy to implement delirium instruments for ICU patients such as the Confusion Assessment Method for the ICU (CAM-ICU). For example, fever, pain, poisons (including toxic drug reactions), brain injury, surgery, traumatic shock, lack of food or water or sleep, and even withdrawal symptoms of certain drug and alcohol dependent states, are all known to cause delirium.

In addition, there is an interaction between acute and chronic symptoms of brain dysfunction; delirious states are more easily produced in people already suffering with underlying chronic brain dysfunction.

A very common cause of delirium in elderly people is a urinary tract infection, which is easily treatable with antibiotics, reversing the delirium.

Too many to list by specific pathology, major categories of the cause of delirium include:

Critical illness

The most common behavioral manifestation of acute brain dysfunction is delirium, which occurs in up to 60% to 80% of mechanically ventilated medical and surgical ICU patients and 50% to 70% of non-ventilated medical ICU patients.

During the ICU stay, acute delirium is associated with complications of mechanical ventilation including nosocomial pneumonia, self-extubation, and reintubation.

The elderly may be at particular risk for this spectrum of delirium and dementia. A firm understanding of the pathophysiologic mechanisms of delirium remains elusive despite improved diagnosis and potential treatments.

Substance withdrawal

Drug withdrawal is a common cause of delirium. The most notable are alcohol withdrawal and benzodiazepine withdrawal but other drug withdrawals both from licit and illicit drugs can sometimes cause delirium.

Gross structural brain disorders

  • Head trauma (i.e., concussion, traumatic bleeding, penetrating injury, etc.)
  • Gross structural damage from brain disease (stroke, spontaneous bleeding, tumor, etc.)

Neurological disorders

  • Various neurological disorders
  • Lack of sleep

Circulatory

  • Intracranial Hypertension

Lack of essential metabolic fuels, nutrients, etc.

  • Hypoxia,
  • Hypoglycemia
  • Electrolyte imbalance (dehydration, water intoxication)

Toxication

  • Intoxication various drugs, alcohol, anesthetics
  • Sudden withdrawal of chronic drug use ("de-tox") in a person with certain types of drug addiction (e.g. alcohol, see delirium tremens, and many other sedating drugs)
  • Poisons (including carbon monoxide and metabolic blockade)
  • Medications including psychotropic medications

Mental illness per se is not a cause, as a matter of definition

Some mental illnesses, such as mania, or some types of acute psychosis, may cause a rapidly fluctuating impairment of cognitive function and ability to focus. However, they are not technically causes of delirium, since any fluctuating cognitive symptoms that occur as a result of these mental disorders are considered ''by definition'' to be due to the mental disorder itself, and to be a part of it. Thus, ''physical'' disorders can be said to produce delirium as a mental side-effect or symptom; however primary ''mental'' disorders which produce the symptom cannot be put into this category, once identified. However, such symptoms may be impossible to distinguish clinically from delirium resulting from physical disorders, if a diagnosis of an underlying mental disorder has yet to be made.

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Delirium Diagnosis

Differential points from other processes and syndromes that cause cognitive dysfunction:

  • Delirium may be distinguished from psychosis, in which consciousness and cognition may not be impaired (however, there may be overlap, as some acute psychosis, especially with mania, is capable of producing delirium-like states).
  • Delirium is distinguished from dementia (chronic organic brain syndrome) which describes an "acquired" (non-congenital) and usually irreversible cognitive and psychosocial decline in function. Dementia usually results from an identifiable degenerative brain disease (for example Alzheimer disease or Huntington's disease). Dementia is usually not associated with a change in level of consciousness, and a diagnosis of dementia requires a chronic impairment.
  • Delirium is distinguished from depression.
  • Delirium is distinguished by time-course from the confusion and lack of attention which result from long term learning disorders and varieties of congenital brain dysfunction. Delirium has also been referred to as 'acute confusional state' or 'acute brain syndrome'. The key word in both of these descriptions is "acute" (meaning: of ''recent onset''), since delirium may share many of the clinical (i.e., symptomatic) features of dementia, developmental disability, or attention-deficit hyperactivity disorder, with the important ''exception'' of symptom duration.
  • Delirium is not the same as confusion, although the two syndromes may overlap and be present at the same time. However, a confused patient may not be delirious (an example would be a stable, demented person who is disoriented to time and place), and a delirious person may not be confused (for example. a person in severe pain may not be able to focus attention, but may be completely oriented and not at all confused).

It is a corollary of the above differential criteria that a diagnosis of delirium ''cannot'' be made without a previous assessment or knowledge of the affected person's ''baseline'' level of cognitive function.

Several valid and reliable rating scales now exist which can be used to accurately diagnose delirium by trained individuals. www.icudelirium.org

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Delirium Treatments

Delirium is not a disease, but a syndrome (i.e. collection of symptoms) indicating dysfunction of the brain, in the same way shortness of breath describes dysfunction of the respiratory system, but does not identify the disorder.

Treatment of delirium involves two main strategies.

First, treatment of the underlying presumed acute cause or causes.

Second, optimising conditions for the brain. This involves ensuring that the patient with delirium has adequate oxygenation, hydration, nutrition, and normal levels of metabolites, that drug effects are minimised, constipation treated, pain treated, and so on.

Detection and management of mental stress is also very important. Thus, the traditional concept that the treatment of delirium is 'treat the cause' is not adequate; patients with delirium actually require a highly detailed and expert analysis of all the factors which might be disrupting brain function.

The first line choice of pharmacological treatment for delirium depends on its cause.

Antipsychotics are the most commonly used drugs for delirium and the most studied. Benzodiazepines themselves can cause delirium or worsen it and are generally ineffective for most causes of delirium; however, if delirium is due to sedative-hypnotic withdrawal, e.g. alcohol withdrawal or benzodiazepine withdrawal or the patient cannot take antipsychotics (e.g. in Parkinson's disease then benzodiazepines are recommended and the most effective treatment.

Palliative or symptomatic treatment of delirium is sometimes necessary to make a patient comfortable.

Antipsychotics, preferably those with minimal anticholinergic activity, such as haloperidol or risperidone may be preferred.

Other evidence also suggests that non-pharmacological measures may also be effective in decreasing the incidence of delirium.

Because delirium is a mere symptom of another problem which may be very subtle, the wisdom of treatment of the delirious patient with drugs must overcome natural skepticism, and requires a high degree of skill.

There have been reports that cholinesterase inhibitors might be effective in treating delirium, but there is little evidence for this.

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Delirium Symptoms

In common usage, delirium is often used to refer to drowsiness, disorientation, and hallucination.

In broader medical terminology, however, a number of other symptoms, including a sudden inability to focus attention, and even (occasionally) sleeplessness and severe agitation and irritability, also define "delirium," and hallucination, drowsiness, and disorientation are not required.

Known before as 'acute confusional state', delirium is one of the oldest forms of mental disorder known in medical history.

There are several medical definitions of delirium (including those in the DSM-IV and ICD-10). However, all include some core features.

The core features are:

  • Disturbance of consciousness (that is, reduced clarity of awareness of the environment, with reduced ability to focus, sustain, or shift attention)
  • Change in cognition (e.g., problem-solving impairment or memory impairment) or a perceptual disturbance
  • Onset of hours to days, and tendency to fluctuate.

Common features also tend to include:

  • Intrusive abnormalities of awareness and affect, such as hallucinations or inappropriate emotional states.

This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Delirium" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.