Dr. Md. Rashidul Haque, MBBS, FCPS (Psychiatry)

Fig: Delirium

Delirium is an acute, fluctuating, generalized cognitive impairment in which the patient has altered consciousness and disorientation.

We have to understand some basic terms to know about delirium and other cognitive disorders.

Organic: Psychiatric disorders which has a biological or chemical etiology are called organic (e.g., dementia, hepatic encephalopathy, uremic syndrome, etc.).

Functional: Those brain disorders with no generally accepted organic basis were called functional disorders (e.g., depression, schizophrenia, anxiety disorder, etc.).

Neuropsychiatry: It focuses on the psychiatric aspects of neurological disorders and the role of brain dysfunction in psychiatric disorders.

Neuropsychiatry is sometimes used interchangeably with Organic  Psychiatry.

Organic Psychiatry: Neuropsychiatry + psychiatric disorders that arise from general medical conditions with their basis outside the brain (e.g. endocrine and metabolic disorders).

Cognition: Multiple domains of the brain include memory, language, orientation, judgment, conducting interpersonal relationships, performing actions (praxis), and problem-solving.

Cognitive disorders: Disruption in one or more of the above domains, and are also frequently complicated by behavioral symptoms. 

Fig: Cognition

Synonymous of Delirium:

Intensive care unit psychosis/Acute confusional state/Acute brain failure/Encephalopathy/Toxic metabolic state/Central nervous system toxicity/Paraneoplastic limbic encephalitis/Sundowning syndrome, Cerebral insufficiency/Organic brain syndrome.


The prevalence of delirium in the elderly is 1-2% in community samples. It is much more common elderly than for younger people. In the community studies, age 55 years or elder 1% & age 85 years and older 13% develop delirium.

Prevalence in General Medical setting – 10-30%, Emergency department – 7-10%, Orthopedic surgery patients – 33%, Open heart surgery patient – 30%, Post operative patients –  15-53%, ICU units – 70-87%, End of life care – 83%, Severe burns -21%, AIDS patients – 40%, Terminally ill patients – 80%.

Clinical features:

*Altered consciousness & disorientation in time and place. (Hallmark of delirium) *Impaired attention.

*Often psychomotor hyperactivity and hypoactivity.

*Emotional disturbances, Anxiety, irritability, depression, and emotional lability.

*Thought –Disorganization of thought processes (ranging from mild tangentiality to frank incoherence). Muddled thinking.

*Perceptual disturbances –Illusions & hallucination (visual and auditory hallucinations).

Fig: Perceptual disturbances

*Neurological symptoms –Autonomic hyperactivity or instability, myoclonic jerking, dysarthria, tremor, asterixis, nystagmus, incoordination, and urinary incontinence are common.

*Sleep disturbances –Disruption of the sleep-wake cycle (often manifested as fragmented sleep at night, with or without daytime drowsiness).

• Risk of delirium

Predisposing factors:

*Age 65 years and older *Male sex *Cognitive impairment

or Dementia. *Sensory impairment *Dehydration *Severe medical illness *Neurological diseases

*Treatment with drugs with anticholinergic properties.*Alcohol abuse *Chronic renal & hepatic disease *Metabolic derangement *Terminal illness

Precipitating factors:

*Drugs – ü Sedatives-hypnotics ü Anticholinergics ü Narcotics ü Polypharmacy ü Alcohol or drug withdrawal

*Inter-current infection – üInfections (e.g. UTI, RTI) üSepticaemia üHypoxia üShock üSevere acute illness üAnaemia üFever or hypothermia üDehydration üPoor nutritional status üLow serum albumin

* Primary neurological diseases-  Stroke • Meningitis • Encephalitis *  Surgery – 

*Environment- •  Admission to ICU •  Use of physical retrains •  Use of bladder catheter •  Pain •  Emotional stress •  Prolong sleep deprivation



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