In common usage, delirium is often used to refer to drowsiness, disorientation, and hallucination. In
medical terminology, however, a number of different symptoms, including temporary disturbance in consciousness, with reduced ability to focus attention and solve problems, are the core features of delirium. Occasionally sleeplessness and severe agitation and irritability are part of "delirium." Hallucination, drowsiness, and disorientation are not required, but may be contribute to the diagnosis.
Delirium is a syndrome encompassing an array of neuropsychiatric symptoms, including a disturbance in
consciousness/attention and
cognition that develops acutely and tends to fluctuate.
[8] The change in cognition (memory deficit, disorientation, language disturbance) or the development of a disturbance, must be one that is not better accounted for by a pre-existing, established, or evolving
dementia.
[10]Other symptoms can include
disorientation,
thought disorder,
memory problems, language disorder,
sleep disturbance,
delusions,
mood lability, psychomotor changes (changes in rate of activity/movement), and
hallucinations.
[8]
Delirium occurs as a stage of consciousness in the continuum between normal awakeness/alertness and coma. During the 20th century, delirium was described as a ‘clouding of consciousness’ but this rather nebulous concept has been replaced by a better understanding of the components of phenomenology that culminate in severely impaired higher order brain functions. Lipowski described delirium as a disorder of attention, wakefulness, cognition, and motor behaviour, while a disturbance in attention is often considered the cardinal symptom.
[8]Disrupted
sleep-wake cycles can result from a loss of normal circadian rhythm.
[8]
Accumulating evidence indicates three core domains of delirium phenomenology: cognition, composed of inattention and other cognitive deficits; higher level thinking processes, including impaired executive function, semantic expression and comprehension; and circadian rhythm, including altered motor activity and fragmented sleep-wake cycle.
[11]Phenomenology studies suggest that core symptoms occur with greater frequency while other less consistent associated symptoms may reflect the biochemical influence of particular aetiologies or genetic, neuronal or physiological vulnerabilities.
[11]
Delirium may present in hyperactive, hypoactive, or mixed forms. In its hyperactive form, it is manifested as severe confusion and disorientation, developing with relatively rapid onset and fluctuating in intensity. In its hypoactive form, it is manifested by an equally sudden withdrawal from interaction with the outside world. Delirium may occur in a mixed type where someone may fluctuate between both hyper- and hypoactive periods. Delirium as a syndrome is one which occurs more frequently in people in their later years. However, when it occurs in the course of a critical illness, delirium has been found to occur in young and old patients at relatively even rates.
Inattention and associated cognitive deficitsEdit
Inattention is the cardinal and required symptom to diagnose delirium and is noticeable on interview by distractibility and inability to shift and / or sustain
attention.
[12]More formal testing can include the months of the year backwards, serial sevens or digit span tests. Disorientation (another symptom of confusion, and usually a more severe one) describes the loss of awareness of the surroundings, environment and context in which the person exists. It may also appear with delirium, but it is not required, as noted. Disorientation may occur in time (not knowing what time of day, day of week, month, season or year it is), place (not knowing where one is) or person (not knowing who one is).
Memory impairment occurs
[8] and is linked to inattention. Reduction in formation of new long-term memory (which by definition survives withdrawal of attention), is common in delirium, because initial formation of (new) long-term memories generally requires an even higher degree of attention than do short-term memory tasks. Since older memories are retained without need of concentration, previously formed long-term memories (i.e., those formed before the period of delirium) are usually preserved in all but the most severe cases of delirium.
Higher level thinkingEdit
Delirious patients have diminished comprehension as evidenced by reduced ‘grasp’ of their surroundings and difficulties in connecting with their immediate environment,
executive dysfunction affecting abstraction, initiation/perseveration, switching mental sets, working memory, temporal sequencing and organization, insight and judgment. Though none of these cognitive deficits is specific to delirium, the array and pattern is highly suggestive.
Language disturbances in delirium include
anomic aphasia,
paraphasias, impaired comprehension,
agraphia, and word-finding difficulties. Incoherent or illogical / rambling conversation is reported commonly. Disorganised thinking includes tangentiality, circumstantiality and a proneness to loose associations between elements of thought which results in speech that often makes limited sense with multiple apparent irrelevancies. This aspect of delirium is common but often difficult for non-experts to assess reliably.
Sleep changesEdit
Disruption of sleep-wake cycle is almost invariably present in delirium and often predates the appearance of a full-blown episode. Minor disturbances with insomnia or excessive daytime somnolence may be hard to distinguish from other medically ill patients without delirium, but delirium typically involves more substantial alterations with sleep fragmentation or even complete sleep-wake cycle reversal that reflect disturbed circadian rhythm regulation. The relationship of circadian disturbances to the characteristic fluctuating severity of delirium symptoms over a 24-hour period or to motor disturbance is unknown.
Motor activity alterations are very common in delirium. They have been used to define clinical subtypes (hypoactive, hyperactive, mixed) though studies are inconsistent as to the prevalence of these subtypes.
[13]Cognitive impairments and EEG slowing are comparable in hyperactive and hypoactive patients though other symptoms may vary. Psychotic symptoms occur in both although the prevailing stereotype suggests that they only occur in hyperactive cases. Hypoactive cases are prone to non detection or misdiagnosis as depression. A range of studies suggest that motor subtypes differ regarding underlying pathophysiology, treatment needs, and prognosis for function and mortality though inconsistent subtype definitions and poorer detection of hypoactives impacts interpretation of these findings.
[14]
Psychotic symptoms occur in up to 50% of patients with delirium. 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. Thought content abnormalities include suspiciousness, overvalued ideation and frank delusions.
Delusions are typically poorly formed and less stereotyped than in schizophrenia or Alzheimer’s disease. They usually relate to persecutory themes of impending danger or threat in the immediate environment (e.g. being poisoned by nurses). Misperceptions include depersonalisation, delusional misidentifications, illusions and hallucinations. Hallucinations and illusions are frequently visual though can be tactile and auditory. Abnormalities of affect which may attend the state of delirium may include many distortions to perceived or communicated emotional states. Emotional states may also fluctuate, so that a delirious person may rapidly change between, for example, terror, sadness and jocularity.
[15]
Persistent deliriumEdit
It was thought for many years that all delirium was a transient state of brain dysfunction that fluctuated on an hourly basis. English medical writer
Philip Barrow noted in 1583 that if delirium resolves, it may be followed by a "loss of memory and reasoning power." Recent long-term studies bear this out, showing that many patients end up meeting criteria for delirium for an alarmingly long time.
[16] For example, in ICU cohorts, it is common to find that 10% of patients still have delirium at the time of hospital discharge.
[17]
Dementia in ICU survivorsEdit
Dementia is supposed to be an entity that continues to decline, such as Alzheimer’s disease. Another way of looking at dementia, however, is not strictly based on the decline component but on the degree of memory and executive function problems. It is now known, for example, that between 50% and 70% of ICU patients have tremendous problems with ongoing brain dysfunction that looks a lot like the degree of problems experienced by Alzheimer’s or TBI (traumatic brain injury) patients and which leaves too many ICU survivors disabled and unable to go back to work and unable to serve effectively as the matriarchs and patriarchs of their families.
[18]This is a distressing personal and public health problem that is getting an increasing amount of scrutiny in ongoing investigations. The implications of such an “acquired dementia-like illness” (note: the term here is being used in a circumstance in which not all patients continue to decline as some have persistent yet stable brain dysfunction and others with newly acquired brain problems can recover fully) are profound at the private level, dismantling the person’s life in very practical ways such as inability to find a car in a parking lot or even complete shopping lists or job-related tasks done previously for years. The societal relevance is also huge when one considers work-force issues related to the inability of a young wage earner being unable to work because of either being a newly disabled ICU survivor themselves or because they now have to care for their family member who is now suffering this “dementia-like” illness following ICU care.
Causes
Delirium arises through the interaction of a number of predisposing and precipitating factors. A predisposing factor might be any biological, psychological or social factor that increases an individual’s susceptibility to delirium. An individual with multiple predisposing factors is said to have "high baseline vulnerability". A precipitating factor is any biological, psychological or social factor that can trigger delirium. The division of causes into "predisposing" and "precipitating" is useful in order to assess an individual’s risk of suffering from delirium, and in guiding the management of delirium – however there may be a significant degree of overlap between the two categories.
Delirium most commonly affects the old age and those of ill health. Health results from physical and socioeconomic assets, and opposing factors come from physical and socioeconomic deficits. Individuals with significant predisposing factors don't compensate for physical or social stressors ("precipitating factors"). In such an individual, a single or mild precipitating factor could be sufficient to trigger an episode of delirium. Conversely, delirium may only result in a healthy individual if they suffer serious or multiple precipitating factors. It is important to note that the factors affecting those of an individual can change over time, thus an individual’s risk of delirium is in a state of flux.
Predisposing factorsEdit
The most important predisposing factors are listed below:
[19]
Precipitating factorsEdit
Any acute factors that affect neurotransmitter, neuroendocrine or neuroinflammatory pathways can precipitate an episode of delirium in a vulnerable brain. Clinical environments can also precipitate delirium, and optimal nursing and medical care is a key component of delirium prevention. Some of the most common precipitating factors are listed below:
- Metabolic [20]
- Infection
- Especially respiratory and urinary tract infections
- Medication
- General Anesthetic
- Vascular
- Physical/psychological stress
- Pain
- Iatrogenic event, esp. post-operative, mechanical ventilation in ICU
- Chronic/terminal illness, esp. cancer
- Post-traumatic event (e.g., fall, fracture)
- Immobilisation/restraint
- Severe constipation/fecal impaction
- Urinary retention
- Other
- Substance withdrawal (esp. alcohol, benzodiazepines)
- Substance intoxication
- Traumatic head injury
Neuropathology...... See www.wikipedia.org.wiki.org/delerium
In common usage, delirium is often used to refer to drowsiness, disorientation, and hallucination. In
medical terminology, however, a number of different symptoms, including temporary disturbance in consciousness, with reduced ability to focus attention and solve problems, are the core features of delirium. Occasionally sleeplessness and severe agitation and irritability are part of "delirium." Hallucination, drowsiness, and disorientation are not required, but may be contribute to the diagnosis.
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)[8]
- Change in cognition (e.g., problem-solving impairment or memory impairment) or a perceptual disturbance (hallucination)[8]
- Onset of hours to days, and tendency to fluctuate.[8]
- Behaviour may be either overactive or underactive, and sleep is often disturbed, with loss of the normal circadian rhythm.[8]
- Thinking is slow and muddled but the content is often complex.[9]
Signs and symptomsEdit
Delirium is a syndrome encompassing an array of neuropsychiatric symptoms, including a disturbance in
consciousness/attention and
cognition that develops acutely and tends to fluctuate.
[8] The change in cognition (memory deficit, disorientation, language disturbance) or the development of a disturbance, must be one that is not better accounted for by a pre-existing, established, or evolving
dementia.
[10]Other symptoms can include
disorientation,
thought disorder,
memory problems, language disorder,
sleep disturbance,
delusions,
mood lability, psychomotor changes (changes in rate of activity/movement), and
hallucinations.
[8]
Delirium occurs as a stage of consciousness in the continuum between normal awakeness/alertness and coma. During the 20th century, delirium was described as a ‘clouding of consciousness’ but this rather nebulous concept has been replaced by a better understanding of the components of phenomenology that culminate in severely impaired higher order brain functions. Lipowski described delirium as a disorder of attention, wakefulness, cognition, and motor behaviour, while a disturbance in attention is often considered the cardinal symptom.
[8]Disrupted
sleep-wake cycles can result from a loss of normal circadian rhythm.
[8]
Accumulating evidence indicates three core domains of delirium phenomenology: cognition, composed of inattention and other cognitive deficits; higher level thinking processes, including impaired executive function, semantic expression and comprehension; and circadian rhythm, including altered motor activity and fragmented sleep-wake cycle.
[11]Phenomenology studies suggest that core symptoms occur with greater frequency while other less consistent associated symptoms may reflect the biochemical influence of particular aetiologies or genetic, neuronal or physiological vulnerabilities.
[11]
Delirium may present in hyperactive, hypoactive, or mixed forms. In its hyperactive form, it is manifested as severe confusion and disorientation, developing with relatively rapid onset and fluctuating in intensity. In its hypoactive form, it is manifested by an equally sudden withdrawal from interaction with the outside world. Delirium may occur in a mixed type where someone may fluctuate between both hyper- and hypoactive periods. Delirium as a syndrome is one which occurs more frequently in people in their later years. However, when it occurs in the course of a critical illness, delirium has been found to occur in young and old patients at relatively even rates.
Inattention and associated cognitive deficitsEdit
Inattention is the cardinal and required symptom to diagnose delirium and is noticeable on interview by distractibility and inability to shift and / or sustain
attention.
[12]More formal testing can include the months of the year backwards, serial sevens or digit span tests. Disorientation (another symptom of confusion, and usually a more severe one) describes the loss of awareness of the surroundings, environment and context in which the person exists. It may also appear with delirium, but it is not required, as noted. Disorientation may occur in time (not knowing what time of day, day of week, month, season or year it is), place (not knowing where one is) or person (not knowing who one is).
Memory impairment occurs
[8] and is linked to inattention. Reduction in formation of new long-term memory (which by definition survives withdrawal of attention), is common in delirium, because initial formation of (new) long-term memories generally requires an even higher degree of attention than do short-term memory tasks. Since older memories are retained without need of concentration, previously formed long-term memories (i.e., those formed before the period of delirium) are usually preserved in all but the most severe cases of delirium.
Higher level thinkingEdit
Delirious patients have diminished comprehension as evidenced by reduced ‘grasp’ of their surroundings and difficulties in connecting with their immediate environment,
executive dysfunction affecting abstraction, initiation/perseveration, switching mental sets, working memory, temporal sequencing and organization, insight and judgment. Though none of these cognitive deficits is specific to delirium, the array and pattern is highly suggestive.
Language disturbances in delirium include
anomic aphasia,
paraphasias, impaired comprehension,
agraphia, and word-finding difficulties. Incoherent or illogical / rambling conversation is reported commonly. Disorganised thinking includes tangentiality, circumstantiality and a proneness to loose associations between elements of thought which results in speech that often makes limited sense with multiple apparent irrelevancies. This aspect of delirium is common but often difficult for non-experts to assess reliably.
