Delirium
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Direct answer
Delirium is an acute disturbance of attention and awareness that develops over a short period (hours to days), fluctuates over the course of the day, and is caused by an underlying medical condition, substance intoxication or withdrawal, toxin exposure, or multiple aetiological factors. Inattention is its hallmark, accompanied by disorganised thinking, altered consciousness, perceptual disturbances (misperceptions and visual hallucinations), sleep-wake disruption and abnormal psychomotor activity ranging from hyperactive agitation to the commoner, easily missed hypoactive quiet state. It is a medical emergency of the elderly hospitalised patient; diagnosis is bedside-based with the Confusion Assessment Method, the EEG shows diffuse slowing, and management is treatment of the cause with environmental support and cautious low-dose antipsychotic medication.
What you must remember
- Four CAM features: acute onset and fluctuating course, inattention, disorganised thinking and altered consciousness — diagnosis needs the first two plus either of the last two.
- Rule of thirds by activity: hyperactive (agitated, hallucinating), hypoactive (quiet, withdrawn, easily missed, worst outcomes) and mixed — hypoactive is at least as common as hyperactive.
- EEG signature: diffuse background slowing in most causes; low-voltage fast activity in withdrawal states such as delirium tremens; a normal EEG argues against delirium.
- Common causes in the elderly: infection, dehydration and electrolyte disturbance, hypoxia, postoperative states, drugs (anticholinergics, benzodiazepines, opioids), retention and impaction, metabolic failure and stroke; polypharmacy is a dominant reversible driver.
- Withdrawal delirium: delirium tremens at 48-72 hours after alcohol cessation, with fast EEG activity, treated with benzodiazepines and thiamine — the one delirium where benzodiazepines are the specific answer.
- Management protocol: treat the cause, reorient, normalise sleep-wake cycles, sensory aids on, mobilise early, avoid restraint and minimise tethers; low-dose haloperidol (or quetiapine) for dangerous agitation, avoiding antipsychotics in Lewy body dementia where possible.
- Outcome: longer stay, higher mortality and increased risk of subsequent dementia; persistence in a third blurs the old "always reversible" teaching.
Common confusion
Dementia versus delirium is the high-yield table asked every year: delirium is acute, fluctuating, attention-first with clouded consciousness; dementia is chronic, progressive, memory-first with clear consciousness. Delirium versus acute psychosis turns on disorientation, visual hallucinations in medical illness and EEG slowing. Remember "sundowning" in dementia and that hypoactive delirium mimics depression in the quiet ward patient.
Exam-focused takeaway
NEET-PG presents an elderly patient two days after surgery, inattentive, awake at night seeing "people in the room", drifting between drowsiness and agitation — delirium with the Confusion Assessment Method as the diagnostic answer and a cause-hunt as the management answer. One-liners test the EEG finding (diffuse slowing), the hypoactive subtype, the 48-72 hour timing of delirium tremens, and haloperidol as the standard drug choice with benzodiazepines reserved for withdrawal. Expect multi-select style stems on risk factors: advanced age, dementia, infection, polypharmacy, sensory impairment and surgery.
Frequently asked questions
What is the hallmark feature of delirium?
Inattention — the patient cannot sustain or shift attention, shown by failed serial sevens or reverse-months testing.
Which screening tool is used for delirium at the bedside?
The Confusion Assessment Method: acute fluctuating onset plus inattention, with disorganised thinking or altered consciousness.
What does the EEG show in delirium?
Diffuse background slowing; low-voltage fast activity in withdrawal-related delirium.
What is hypoactive delirium?
A quiet, withdrawn presentation without agitation — common, often missed, with poor prognosis.
Which drug is preferred for agitation in delirium?
Low-dose haloperidol with ECG monitoring; benzodiazepines only for alcohol or sedative withdrawal.
How is delirium treated fundamentally?
By correcting the underlying cause, supported by reorientation, sensory aids and early mobilisation.