About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
Key points
- Treat AMS as a syndrome, not a diagnosis: ABCs, glucose, oxygenation, infection, toxidrome and neurological signs first.
- Delirium is acute, fluctuating inattention with altered awareness; dementia is chronic decline with stable consciousness.
- Older adults often present with delirium from infection, medication, dehydration, pain, urinary retention or constipation.
- Focal deficits, meningism, seizure, trauma, anticoagulation or reduced GCS require urgent neurological workup.
- Non-pharmacological delirium care is first-line; antipsychotics are reserved for severe distress or danger after reversible causes are addressed.
Approach to the Presentation
Begin with reversible killers: hypoxia, hypoglycaemia, sepsis, shock, intoxication, withdrawal and intracranial catastrophe. Establish baseline cognition from collateral history and determine time course. Use CAM-style features: acute change/fluctuation, inattention, disorganized thinking and altered level of consciousness.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Hypoglycaemia | must-not-miss | Sweating, tremor, diabetes medication, seizure or coma | Point-of-care glucose |
| Sepsis / CNS infection | must-not-miss | Fever or hypothermia, tachycardia, hypotension, meningism, rash or immunosuppression | Cultures, lactate, CBC, LP when indicated |
| Stroke / intracranial haemorrhage | must-not-miss | Focal deficits, severe headache, anticoagulation, reduced consciousness | Urgent CT/CTA brain |
| Drug intoxication or withdrawal | must-not-miss | Opioids, benzodiazepines, alcohol, anticholinergics, sedatives; autonomic findings | Toxidrome assessment, medication review, targeted toxicology |
| Delirium from medical illness | common | Acute fluctuating attention impairment in older/frail patient; infection, dehydration, pain, retention, constipation | CAM, urinalysis only when urinary symptoms/systemic signs, labs directed by history |
| Electrolyte/endocrine encephalopathy | common | Sodium/calcium disorders, renal/hepatic failure, thyroid/adrenal disease | Electrolytes, renal/liver function, TSH/cortisol where indicated |
| Dementia | common | Chronic progressive decline without acute fluctuation; may have superimposed delirium | Collateral history and cognitive assessment after acute illness |
| Post-ictal state/non-convulsive status | less common | Recent seizure, fluctuating unresponsiveness, subtle automatisms | EEG if persistent unexplained AMS |
| Primary psychiatric disorder | less common | Psychosis or mood disorder with preserved attention/orientation; diagnosis after medical causes excluded | Mental status exam and collateral |
Red Flags & Key History
Symptoms
Reduced GCS, airway compromise or hypoxia
Fever, meningism or sepsis features
New focal neurological deficit or seizure
Recent fall/head trauma or anticoagulant use
Acute fluctuating inattention in an older patient
Signs
Hypoglycaemia
Meningism or petechial rash
Focal neuro signs
Urinary retention, dehydration, pain or constipation
Approach to Investigation
First-line
ABCs, oxygen saturation, glucoseImmediate bedside priorities.
Medication/toxin reviewAnticholinergics, sedatives, opioids, alcohol and polypharmacy are common.
CBC, electrolytes, creatinine, LFTs, calcium, urinalysis when indicatedTarget common metabolic/infectious precipitants.
ECGDrug toxicity, arrhythmia, QT effects.
Second-line
CT headFocal signs, trauma, anticoagulation, severe headache, reduced GCS or unexplained persistent AMS.
Lumbar punctureSuspected meningitis/encephalitis after imaging if indicated.
EEGSuspected non-convulsive status epilepticus.
Specialist
Geriatrics/psychiatry/neurologyPersistent delirium, safety concerns, suspected seizures/CNS disease or complex behavioural symptoms.
Management Principles
MCC Delirium objective + Canadian seniors mental health delirium guidance1
Immediate treatment
- Correct hypoxia and hypoglycaemia immediately
- Treat sepsis/meningitis empirically when suspected
- Reverse opioid toxicity with naloxone if respiratory depression
2
Delirium care
- Reorientation, glasses/hearing aids, hydration, sleep-wake normalization, mobilization and family presence
- Remove catheters/restraints where possible; treat pain, retention and constipation
3
Agitation
- Use verbal de-escalation and treat cause first
- Low-dose antipsychotic only if severe distress or danger; avoid routine benzodiazepines except alcohol/benzodiazepine withdrawal
Complications & Pitfalls
- Assuming UTI from confusion alone: asymptomatic bacteriuria is common; look for urinary/systemic features.
- Missing hypoglycaemia: glucose is immediate.
- Calling delirium dementia: delirium is acute and fluctuating.
- Using sedatives first: non-drug measures and cause treatment are core.
MCCQE1 Exam Tips
- 1Glucose is always a first test in AMS.
- 2Delirium = acute fluctuating inattention.
- 3Dementia does not usually reduce consciousness unless delirium is superimposed.
- 4Benzodiazepines worsen most delirium except withdrawal states.
- 5Collateral history is essential for baseline cognition.
- 6CT head is for focal signs, trauma, anticoagulation, severe headache or persistent unexplained AMS.
Put your reading into practice
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