14.4 Delirium

Acute Confusional State: Delirium is defined as an organically caused decline from a previous baseline mental functioning that develops over a short period of time, typically hours to days.
Syndrome: It encompasses disturbances in attention, consciousness, and cognition.
Neurological Deficits: May also involve other disturbances such as psychomotor disturbances (e.g., hyperactive, hypoactive, or mixed), impaired sleep-wake cycle, emotional disturbances, and perceptual disturbances (e.g., hallucinations and delusions). Not all features are required for diagnosis.
Cause: Arises from an acute organic process identifiable with structural, functional, or chemical problems in the brain, often resulting from external diseases affecting brain function.

Underlying Disease Processes: E.g. infections or hypoxia.
Medications: Side effects or withdrawal symptoms from drugs, sedation or over-consumption of alcohol and usage of hallucinogenic deliriants.
Health Factors: Includes malnutrition, pain, and psychiatric processes like schizophrenia or bipolar disorder, which do not meet the criteria for delirium.

Difficulty Diagnosing: Requires establishing a person's usual mental function; overlapping signs and symptoms can confuse diagnosis with psychiatric disorders or chronic organic brain syndromes, such as dementia and depression.
Differentiation from Dementia: Dementia describes chronic, often irreversible cognitive decline whereas delirium is often of acute duration and fluctuation in cognitive function.

Situational Awareness: Delirium results in difficulty in processing new information and situational awareness, with onset generally rapid (minutes to hours) but lasting a few hours to weeks.
Symptoms: Includes sudden cognitive changes, mood swings, uncharacteristic behaviors, and hallucinations.
Mental Disorders: Other disorders typically lead to gradual cognitive decline such as Alzheimer's disease, depression, and psychotic disorders.

Attribute	Delirium	Alzheimer's Disease	Depression	Psychotic Disorders
Onset	Sudden/acute/subacute	Gradual	Gradual	Acute or gradual
Progression	Shifts in severity, likely to resolve in days to weeks.	Worsens over time	Chronic with acute exacerbation	Acute or chronic with acute exacerbation
Hallucinations	May be present (mostly visual)	Mostly absent	May be present (exceptions: Lewy Body dementia, etc.)	Present
Delusions	Fleeting	Mostly not present	May be present	Present
Psychomotor Activity	Increased or decreased, may shift	May or may not change	Change	Change
Attention	Poor attention span and impaired short term memory.	Progressive worsening	May be altered	May be altered
Consciousness	Altered, rapidly shifts	Mostly intact until severe stages	Normal	Normal
Speech	Not coherent	Errors	Slow	Normal or pressured
Thought	Disorganized	Impoverished	Normal	Disorganized
Perceptions	Altered, rapidly shifts	Mostly intact until severe stages	Normal	May be altered
EEG	Moderate to severe background slowing	Normal or mild diffuse slowing	Normal	Normal
Reversibility	Mostly	Very rarely	Yes	Rarely

Stage of Consciousness: Delirium is positioned on a spectrum between normal wakefulness and coma. It necessitates an acute disturbance in consciousness, attention, and cognition.

Older age (> 65 years old)
Male sex
Cognitive impairment/dementia
Physical comorbidity (e.g., biventricular failure, cancer, cerebrovascular disease)
Psychiatric comorbidities (e.g., depression)
Sensory impairments (e.g., vision, hearing)
Functional dependence (needing assistance with self-care or mobility)
Dehydration/malnutrition
Drug and drug dependence, including alcohol dependence

Prolonged sleep deprivation
Environmental/physical/psychological stress
Inadequately controlled pain
Admission to an intensive care unit
Immobilization or physical restraints
Urinary retention or bladder catheterization
Emotional stress
Severe constipation or fecal impaction
Medications (e.g., sedatives, anticholinergics, dopaminergics, corticosteroids, polypharmacy)
Substance intoxication or withdrawal
Primary neurological diseases
Severe drops in blood pressure (orthostatic hypotension) causing inadequate blood flow (cerebral hypoperfusion)
Strokes or transient ischemic attacks (TIAs)
Intracranial bleeding
Brain inflammation (e.g., meningitis, encephalitis)
Concurrent illnesses and infections (e.g., pneumonia, urinary tract infections)
Latrogenic complications
Hypoxia, hypercapnea, anemia
Poor nutritional status, dehydration, electrolyte imbalances, hypoglycemia
Cardiac shock, heart attacks, heart failure
Metabolic derangements (e.g., SIADH, Addison's disease, hyperthyroidism)
Chronic or terminal illnesses (e.g., cancer)
Post-traumatic events (e.g., falls, fractures)
Surgeries (e.g., cardiac, orthopedic, prolonged cardiopulmonary bypass, thoracic surgeries)

Attention/Vigilance: 100% of cases show poor attention; 64-100% show memory impairment; 45-100% show clouding of consciousness; 43-100% display disorientation; 93% demonstrate acute onset; 59-95% show disorganized thinking; 77% have diffuse cognitive impairment; 41-93% may have language disorders; 25-96% experience sleep disturbances; 43-63% show mood lability; 38-55% exhibit psychomotor changes; 18-68% have delusions; 17-55% present with perceptual changes/hallucinations.

Delirium Rating Scale-Revised-98 (DRS-R-98): Assess various symptoms, helping in diagnosing and analyzing delirium features.
- Inattention: Required symptom; characterized by distractibility and inability to maintain attention.
- Memory Impairment: Linked to inattention; particularly affects formation of new long-term memories.
- Disorientation: This includes loss of awareness regarding self, time, or place.
- Disorganized Thinking: Often evident through incoherent speech and irrelevancies in thought.
- Language Disturbances: Involves impaired linguistic processing reflected in various speech difficulties.
- Sleep Changes: Show irregular circadian rhythms and may reflect nighttime activity with daytime sleep.
- Psychotic Symptoms: May exhibit delusions, with themes usually involving perceived threats.
- Mood Lability: Rapid fluctuations in emotional states.
- Motor Activity Changes: Classified into hypoactive, hyperactive, and mixed subtypes.

Identification and Management: Aim to address underlying causes and manage delirium symptoms while minimizing complications.
Temporary Treatments: May be required to comfort the patient or facilitate care (e.g., preventing removal of medical equipment).
Antipsychotic Use: Not supported for routine treatment or prevention in hospital settings.
Withdrawal Management: Benzodiazepines are used for alcohol or sedative-hypnotic withdrawal cases.

General Care: Evidence supports that systematic general care reduces the incidence of delirium among hospitalized patients.
Prevalence Statistics: Delirium affects 14-24% of hospitalized individuals, with general population prevalence at 1%-2% escalating to 14% among those over age 85, and occurs in 15-53% of older adults post-surgery, 60% in nursing homes or post-acute care, and poses a risk of death for critical care patients within a year.