Definition and Overview
Delirium is a brain dysfunction centered on impairment of attention and consciousness that develops acutely and fluctuates throughout the day. The ability to concentrate, maintain, and shift attention is reduced, and is accompanied by impairments in memory, perception, language, and perception. In ICD-10, it is classified as F05.
Delirium is not a disease with a single cause, but a syndrome that occurs when physical abnormalities affect brain function. Triggers include infection, drugs, metabolic abnormalities, and surgery, and even the same stimulus occurs more easily in patients who are elderly or have underlying cognitive decline. It occurs in a significant number of hospitalized elderly people, and in some groups, such as patients after surgery or in intensive care units, it occurs in up to half.
Differentiation from dementia
Delirium and dementia both show cognitive decline, but the course and reversibility are different.
- Onset: Delirium begins acutely within hours to days, and dementia progresses slowly over months to years.
- Progress: Delirium fluctuates significantly throughout the day, while dementia progresses relatively steadily.
- Attention/Consciousness: In delirium, decreased attention and changes in the level of consciousness are noticeable, but in dementia, consciousness is relatively maintained in the early to middle stages.
- Reversibility: Delirium is usually recovered when the cause is corrected, but degenerative dementia is progressive.
It is common for dementia patients to experience overlapping delirium, and in this case, the guardian's information is used to check whether there has been an acute deterioration in the usual cognitive state.
cause
Delirium is often caused by several factors working together.
- Infections: pneumonia, urinary tract infection, sepsis
- Medications: anticholinergics, benzodiazepines, opioids, polypharmacy, drug withdrawal
- Metabolic abnormalities: dehydration, electrolyte imbalance, hypoglycemia/hyperglycemia, hypoxia, liver/kidney dysfunction
- Surgery/Trauma: Post-operative condition, anesthesia, pain
- Environment/Other: Constipation, urinary retention, sleep deprivation, sensory block, physical inhibition
Old age, existing cognitive decline, severe illness, and impaired vision and hearing are vulnerable factors that can cause delirium even with little stimulation.
Subtype
Delirium is divided into three subtypes depending on psychomotor activity.
- Hyperactivity: Shows agitation, excitement, hallucinations, and aggression. Relatively easy to find.
- Hypoactivity: Shows drooping, drowsiness, and decreased responsiveness. Because it looks quiet, it can easily be mistaken for depression or fatigue and is easy to miss.
- Mixed: Both aspects appear alternately.
Hypoactive delirium tends to have a worse prognosis and requires active screening.
diagnosis
Diagnosis is based on clinical evaluation. Confusion Assessment Method (CAM) is a representative screening tool that evaluates acute onset and fluctuating course, decreased attention, disorganization of thinking, and changes in level of consciousness. In addition to screening, medical history and medication review, blood tests (electrolytes, blood sugar, kidney, liver function, and inflammation indicators), urine tests, and, if necessary, brain imaging and electroencephalography are performed to find the triggering cause.
Prevention and Treatment
The key to prevention and treatment is correction of triggering factors and non-pharmacological approaches.
- Cause correction: Infection treatment, fluid and electrolyte correction, adjustment of causative medication, management of pain, constipation, and urinary retention.
- Non-pharmacological treatment: orientation support, provision of glasses and hearing aids, maintenance of daytime activities and nighttime sleep, early mobilization, family involvement, and minimization of physical restraint.
- Pharmacological treatment: Antipsychotics are used short-term and in small doses only for severe agitation that cannot be controlled with non-pharmacological treatment and poses a risk to oneself or others.
Patients who experience delirium have a high risk of subsequent cognitive decline, prolonged hospitalization, and complications, so early detection and prevention are important.