Delirium overview

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Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Delirium from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Criteria
History and Symptoms
Physical Examination
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Zand, M.D.[2] Pratik Bahekar, MBBS [3]; Vishal Khurana, M.B.B.S., M.D. [4]

Overview

Delirium is an acute and relatively sudden (developing over hours to days) decline in attention-focus, perception, and cognition. Delirium is commonly associated with a disturbance of consciousness or reduced clarity of awareness of the environment. The change in cognition including memory deficit, disorientation, language disturbance or the development of a perceptual disturbance may happen with rapid fluctuation course.The concept of delirium has been evolving over centuries. Delirium was first identified in the 16th century. In the second half of the 19th century, delirium was identified by French workers as chaotic thinking and cognitive failure, clouding of consciousness, temporospatial disorientation. The definition of confusion and delirium was established by Chaslin and Bonhoeffer as the stereotyped manifestations of acute brain failure. Delirium is classified on the basis of etiology, duration, and severity. Hyperactive delirium is defined as increased psychomotor activity, which may occur with increased mood lability, agitation, non cooperative attitude towards medical treatment. Hypoactive delirium is explained by a hypoactive level of psychomotor activity, which may exist along with increased lethargy or stupor, inattentiveness and motor slowness and is much more common among ICU admitted patients with severe disease.The exact pathophysiology of delirium is still being investigated. The roles of neurotransmitters like acetylcholine and dopamine seem to be important. It involves disrupted connectivity between cortical and subcortical areas of the brain, especially areas concerned with sleep and awakening. The role of increased inflammatory cytokines has been shown in delirious patients. Delirium may be caused by severe physical or mental illness, or any process which interferes with the normal metabolism or function of the brain such as fever, pain, poison (toxic drug reactions), brain injury, surgery, traumatic shock, severe lack of food or water or sleep, and even withdrawal symptoms of certain drug and alcohol dependent states. In addition, there is an interaction between acute and chronic symptoms of brain dysfunction. Delirious states are more easily produced in people already suffering from underlying chronic brain dysfunction. A very common cause of delirium in elderly people is a urinary tract infection, which is easily treatable with antibiotics. Delirium, like mental confusion, is a very general and nonspecific symptom of organ dysfunction. In addition to many organic causes relating to a structural defect or a metabolic problem in the brain, there are also some psychiatric causes, which may also include a component of mental or emotional stress, mental disease.Delirium is differentiated from other causes cognitive dysfunction such as psychiatric Disorders, dementia. Unlike dementia, the course of delirium is reversible with fluctuation in level of consciousness.The prevalence of delirium is approximately 23,000 per 100,000 hospitalized patients worldwide. Between May 2009 to August 2012, the incidence of delirium was estimated to be 8700 cases per 100,000 African-Americans in Indianapolis. Delirium is more commonly observed among elderly patients, especially age> 65 year-old. Male < 65 year-old are more commonly affected with delirium. Delirium is more commonly observed among Female≥ 85-year-old with medical comorbidities. There is no racial predilection for delirium. Young African-American patients are less likely to develop delirium compared with Caucasians of the same age.Common risk factors associated with delirium include older age, dementia, hypertension, emergency surgery or trauma before ICU admission, mechanical ventilation, metabolic acidosis, delirium on the prior day , coma.The duration of delirium may vary from hours to months. After remission , delirium may increase the risk of functional decline, cognitive dysfunction, and institutional placement, and with higher mortality. Delirium in the elderly, can cause many complications, which may include pneumonia and decubitus ulcers, prolonging hospital stays. Delirium was associated with longer postoperative recovery periods, longer hospital stays, and long-term disability after orthopedic surgery. Common complications associated with delirium include increased mortality, cognitive impairment, longer durations of mechanical ventilation, longer lengths of stay in the ICU. Prognosis is dependent on the severity of delirium, and the 1 year mortality rate of patients with delirium is approximately 10%-26%.The DSM V, and ICD-10 have provided diagnostic criteria for delirium. Definition based on DSM-5 include disturbance in attention and awareness (reduced ability to direct, focus, shift attention and reduced orientation to envinment), initiation of disturbance over a short period of time during several hours or days with fluctuation in severity over a day, disturbance in cognition (memory deficit, disorientation, language, visuospatial ability, perception, disturbance other than evolving neurocognitive disorder, disturbance due to medical condition, substance intoxication, or withdrawal. Other definitions of delirium include disturbance in cognition, impairment of immediate recall and recent memory, disorientation to time, place, person, disturbance in sleep wake cycle, Psychomotor disturbances,emotional disturbances in a period of less than 6 months.Delirium causes impairment in functions, sleep-wake cycle and also has a behavioral component. Common symptoms associated with delirium include altered level of consciousness, inattention, disorientation, hallucination, delusions, agitation, inappropriate speech, sleep–wake disturbances, Symptom fluctuation, emotional disturbance. Subclinical delirium or prodromal delirium may precede by 1 to 3 days prior to an overt delirium, which presents as restlessness, anxiety, irritability, distractibility, sleep disturbance with less severe cognitive impairment in comparison to delirium.It is important to do a thorough physical examination to find out the underlying etiology of delirium. Systemic physical examination includes testing vital signs such as temperature, pulse rate, blood pressure, and respiration and also evaluation of mental status. Patients may seem disoriented with difficulty in sustaining attention, problem in short-term memory, poor insight and impaired judgment.Laboratory findings may differ according to the etiology of delirium. Following investigations are done in delirium: pulse oximetry, electrolytes, blood glucose, liver function tests, blood urea nitrogen, creatinine, vitamin B12 , Folate levels, measurement therapeutic drug levels, urine drug screen for substance use, blood alcohol level, complete blood count, urinalysis, thyroid function testing, erythrocyte sedimentation rate, C-reactive protein, rapid plasma reagin screening for syphilis, acquired immune deficiency syndrome/human immunodeficiency virus (AIDS/HIV) screening.

Historical Perspective

The concept of delirium has been evolving over centuries. Delirium was first identified in the 16th century. In the second half of the 19th century, delirium was identified by French workers as chaotic thinking and cognitive failure, clouding of consciousness, temporospatial disorientation. The definition of confusion and delirium was established by Chaslin and Bonhoeffer as the stereotyped manifestations of acute brain failure.

Pathophysiology

The exact pathophysiology of delirium is still being investigated. The roles of neurotransmitters like acetylcholine and dopamine seem to be important. It involves disrupted connectivity between cortical and subcortical areas of the brain, especially areas concerned with sleep and awakening. The role of increased inflammatory cytokines has been shown in delirious patients.

Causes

Delirium may be caused by severe physical or mental illness, or any process which interferes with the normal metabolism or function of the brain such as fever, pain, poison (toxic drug reactions), brain injury, surgery, traumatic shock, severe lack of food or water or sleep, and even withdrawal symptoms of certain drug and alcohol dependent states. In addition, there is an interaction between acute and chronic symptoms of brain dysfunction. Delirious states are more easily produced in people already suffering from underlying chronic brain dysfunction. A very common cause of delirium in elderly people is a urinary tract infection, which is easily treatable with antibiotics. Delirium, like mental confusion, is a very general and nonspecific symptom of organ dysfunction. In addition to many organic causes relating to a structural defect or a metabolic problem in the brain, there are also some psychiatric causes, which may also include a component of mental or emotional stress, mental disease.

Differentiating [disease name] from other Diseases

Delirium is differentiated from other causes cognitive dysfunction such as psychiatric Disorders, dementia. Unlike dementia, the course of delirium is reversible with fluctuation in level of consciousness.

Epidemiology and Demographics

The prevalence of delirium is approximately 23,000 per 100,000 hospitalized patients worldwide. Between May 2009 to August 2012, the incidence of delirium was estimated to be 8700 cases per 100,000 African-Americans in Indianapolis. Delirium is more commonly observed among elderly patients, especially age> 65 year-old. Male < 65 year-old are more commonly affected with delirium. Delirium is more commonly observed among Female≥ 85-year-old with medical comorbidities. There is no racial predilection for delirium. Young African-American patients are less likely to develop delirium compared with Caucasians of the same age.

Risk Factors

Common risk factors associated with delirium include older age, dementia, hypertension, emergency surgery or trauma before ICU admission, mechanical ventilation, metabolic acidosis, delirium on the prior day , coma.

Natural History, Complications and Prognosis

The duration of delirium may vary from hours to months. After remission , delirium may increase the risk of functional decline, cognitive dysfunction, and institutional placement, and with higher mortality. Delirium in the elderly, can cause many complications, which may include pneumonia and decubitus ulcers, prolonging hospital stays. Delirium was associated with longer postoperative recovery periods, longer hospital stays, and long-term disability after orthopedic surgery. Common complications associated with delirium include increased mortality, cognitive impairment, longer durations of mechanical ventilation, longer lengths of stay in the ICU. Prognosis is dependent on the severity of delirium, and the 1 year mortality rate of patients with delirium is approximately 10%-26%.

Diagnosis

Diagnostic Criteria

The DSM V, and ICD-10 have provided diagnostic criteria for delirium. Definition based on DSM-5 include disturbance in attention and awareness (reduced ability to direct, focus, shift attention and reduced orientation to envinment), initiation of disturbance over a short period of time during several hours or days with fluctuation in severity over a day, disturbance in cognition (memory deficit, disorientation, language, visuospatial ability, [[perception, disturbance other than evolving neurocognitive disorder, disturbance due to medical condition, substance intoxication, or withdrawal. Other definitions of delirium include disturbance in cognition, impairment of immediate recall and recent memory, disorientation to time, place, person, disturbance in sleep wake cycle, Psychomotor disturbances,emotional disturbances in a period of less than 6 months.

History and Symptoms

Delirium causes impairment in functions, sleep-wake cycle and also has a behavioral component. Common symptoms associated with delirium include altered level of consciousness, inattention, disorientation, hallucination, delusions, agitation, inappropriate speech, sleep–wake disturbances, Symptom fluctuation, emotional disturbance. Subclinical delirium or prodromal delirium may precede by 1 to 3 days prior to an overt delirium, which presents as restlessness, anxiety, irritability, distractibility, sleep disturbance with less severe cognitive impairment in comparison to delirium

Physical Examination

It is important to do a thorough physical examination to find out the underlying etiology of delirium. Systemic physical examination includes testing vital signs such as temperature, pulse rate, blood pressure, and respiration and also evaluation of mental status. Patients may seem disoriented with difficulty in sustaining attention, problem in short-term memory, poor insight and impaired judgment.

Laboratory Findings

Laboratory findings may differ according to the etiology of delirium. Following investigations are done in delirium: pulse oximetry, electrolytes, blood glucose, liver function tests, blood urea nitrogen, creatinine, vitamin B12 , Folate levels, measurement therapeutic drug levels, urine drug screen for substance use, blood alcohol level, complete blood count, urinalysis, thyroid function testing, erythrocyte sedimentation rate, C-reactive protein, rapid plasma reagin screening for syphilis, acquired immune deficiency syndrome/human immunodeficiency virus (AIDS/HIV) screening.

CT scan

There are no CT scan findings associated with [disease name].

OR

[Location] CT scan may be helpful in the diagnosis of [disease name]. Findings on CT scan suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

There are no CT scan findings associated with [disease name]. However, a CT scan may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].

MRI

There are no MRI findings associated with [disease name].

OR

[Location] MRI may be helpful in the diagnosis of [disease name]. Findings on MRI suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

There are no MRI findings associated with [disease name]. However, a MRI may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].

Other Imaging Findings There are no other imaging findings associated with [disease name].

OR

[Imaging modality] may be helpful in the diagnosis of [disease name]. Findings on an [imaging modality] suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

Other Diagnostic Studies There are no other diagnostic studies associated with [disease name].

OR

[Diagnostic study] may be helpful in the diagnosis of [disease name]. Findings suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

Other diagnostic studies for [disease name] include [diagnostic study 1], which demonstrates [finding 1], [finding 2], and [finding 3], and [diagnostic study 2], which demonstrates [finding 1], [finding 2], and [finding 3].

Treatment

Medical Therapy

There is no treatment for [disease name]; the mainstay of therapy is supportive care. The mainstay of therapy for [disease name] is [medical therapy 1] and [medical therapy 2]. [Medical therapy 1] acts by [mechanism of action 1]. Response to [medical therapy 1] can be monitored with [test/physical finding/imaging] every [frequency/duration]. Surgery Surgery is the mainstay of therapy for [disease name]. [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of [disease name]. [Surgical procedure] can only be performed for patients with [disease stage] [disease name].

Prevention

There are no primary preventive measures available for [disease name]. Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3]. Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3].