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Q1: Definition, classification and distinction from dementia (2 min)
- Define delirium using DSM-5. An acute, transient, fluctuating disturbance of attention/awareness caused by a medical condition, substance, medication or toxin — five DSM-5 elements (attention/awareness; acute onset + fluctuation; additional cognitive disturbance; not better explained by coma or pre-existing neurocognitive disorder; physiological consequence of a medical/substance cause).
- Classify by psychomotor subtype. Hyperactive (agitated, hallucinations, recognised), hypoactive (quiet, missed, worst prognosis), mixed (fluctuating between the two — commonest), no-subtype.
- Distinguish from dementia in one line. Delirium = acute + fluctuating + INATTENTION with clouded consciousness, usually reversible. Dementia = chronic + progressive + relatively preserved attention (early) with clear consciousness, usually irreversible. The two often coexist — any acute worsening of dementia is delirium until proven otherwise.
- Why is delirium a medical emergency? In-hospital mortality up to 25 percent; doubled 6-month mortality; predicts long-term cognitive decline; it is a marker of acute brain dysfunction, not a benign confusional state.
Q2: Pathophysiology (2 min)
- Central neurotransmitter model. Acetylcholine DEFICIENCY and dopamine EXCESS. Cholinergic failure explains the elderly vulnerability and why anticholinergic drugs precipitate delirium; dopaminergic excess explains the agitation/hallucinations and why haloperidol (D2 blockade) provides symptomatic relief.
- Neuroinflammation. Peripheral cytokines (IL-1beta, IL-6, TNF-alpha) cross the blood-brain barrier and activate microglia, disrupting synaptic transmission — exaggerated in a primed (ageing, demented) brain.
- Other contributors. Direct neuronal insult (stroke, trauma, hypoxia), network disconnection (default mode network), sleep-wake cycle disruption, HPA-axis dysregulation.
- Why does delirium predict long-term dementia? Sustained neuroinflammation and ischaemia may cause permanent neuronal injury, accelerating a pre-clinical neurodegenerative process — delirium is both a consequence of, and a risk factor for, dementia.
Q3: Diagnosis at the bedside (2 min)
- CAM rule. Features 1 AND 2 AND (3 OR 4): (1) acute onset + fluctuating course, (2) inattention, (3) disorganised thinking, (4) altered level of consciousness. Sensitivity ~94 percent.
- Bedside attention tests. Digit span (normal 7 forward, 5 backward), months of the year backwards, days of the week backwards, serial sevens, the "A test."
- 4AT. Score 4 or more = delirium; rapid, no equipment, suitable for wards and ED.
- CAM-ICU + RASS. Daily screening in intubated ICU patients.
- Investigations. Capillary glucose first; FBC, CRP, U&E, LFTs, Ca, glucose, TSH, urinalysis, CXR, ECG; CT brain if focal neurology, head trauma, anticoagulated with fall, or refractory; EEG to exclude non-convulsive status epilepticus (generalised slowing vs focal/3-Hz spike-wave).
Q4: Management (3 min)
- Overriding principle. Delirium is a syndrome — find and treat every precipitant. Sedatives are symptomatic only.
- Resuscitation. ABCDE; immediately exclude hypoxia (oxygen to SpO2 94-98 percent), hypoglycaemia (glucose; if low, 15-20 g carbohydrate), septic shock (Surviving Sepsis hour-1 bundle).
- Non-pharmacological (HELP bundle). Orientation (clock, calendar), sensory aids, hydration, sleep hygiene, early mobilisation, treat pain, fix constipation/retention, family involvement, deprescribe anticholinergics. Reduced incident delirium ~40 percent (Inouye NEJM 1999).
- Pharmacological — for severe agitation only. Haloperidol 0.5-1 mg PO/IM, lowest dose, caution with IV (QT prolongation — ECG).
- Drugs to avoid. Benzodiazepines WORSEN delirium — except alcohol/benzodiazepine withdrawal (CIWA-Ar protocol, lorazepam/chlordiazepoxide/diazepam) and seizures.
- Two special cases. Wernicke — IV thiamine (Pabrinex) BEFORE glucose. Parkinson's / Lewy body — NEVER typical antipsychotic; use quetiapine 25-50 mg.
- ICU. PADIS 2018 ABCDEF bundle; dexmedetomidine over benzodiazepines; routine antipsychotics do NOT improve outcomes (MIND-USA, NEJM 2018).
Q5: Prognosis and pitfalls (2 min)
- Prognosis. In-hospital mortality up to 25 percent; doubled 6-month mortality; ~30-50 percent still delirious at discharge; predicts accelerated cognitive decline and new incident dementia.
- Worst prognosis. Hypoactive subtype (missed), pre-existing dementia, age, severity/duration, ICU.
- Classic pitfalls. Missing hypoactive delirium; treating with sedatives instead of cause; misdiagnosing as dementia; using a typical antipsychotic in Parkinson's/Lewy body; missing Wernicke; missing non-convulsive status epilepticus; missing a subdural haematoma in an anticoagulated patient who has fallen; giving IV haloperidol without ECG monitoring.