Delirium: MCCQE1 Preparation Guide

Introduction

Delirium is a common, serious, and often preventable neuropsychiatric syndrome characterized by an acute and fluctuating disturbance in attention, awareness, and cognition. For MCCQE1 preparation, understanding delirium is critical as it represents a medical emergency associated with increased morbidity, mortality, and healthcare costs within the Canadian system.

It is a quintessential topic for the Medical Expert and Health Advocate CanMEDS roles, requiring a systematic approach to diagnosis, management, and prevention, particularly in the elderly population.

Pathophysiology and Etiology

The exact pathophysiology involves neurotransmitter imbalances (acetylcholine deficiency and dopamine excess) and neuroinflammation.

The “I WATCH DEATH” Mnemonic

For the MCCQE1, you must quickly generate a differential diagnosis. The standard mnemonic used in Canadian medical education is:

Clinical Presentation

Delirium presents in three motor subtypes. Recognizing these is vital for the exam, as hypoactive delirium is frequently missed.

1. Hyperactive: Agitation, hallucinations, restlessness (often mistaken for psychosis).
2. Hypoactive: Lethargy, sedation, slow responses (often mistaken for depression or fatigue). Most common in elderly.
3. Mixed: Fluctuates between the two.

Delirium vs. Dementia vs. Depression

A classic MCCQE1 task is differentiating these conditions.

Diagnosis

The diagnosis of delirium is clinical. The Confusion Assessment Method (CAM) is the gold standard diagnostic tool referenced in Canadian guidelines.

Management

Management involves treating the underlying cause and managing the symptoms. The Canadian Coalition for Seniors’ Mental Health (CCSMHL) emphasizes non-pharmacological approaches first.

Choosing Wisely Canada Recommendations

Canadian Guidelines & Epidemiology

• Prevalence: Delirium affects 15-50% of hospitalized older adults in Canada.
• Prevention: The Hospital Elder Life Program (HELP) is an evidence-based Canadian standard for preventing delirium in hospitalized seniors.
• Legal: In Canada, if a patient lacks capacity due to delirium, consent must be obtained from the Substitute Decision Maker (SDM). The hierarchy of SDMs varies by province (e.g., Ontario’s Health Care Consent Act).

Key Points to Remember for MCCQE1

• Definition: Acute, fluctuating, inattention.
• Workup: Always rule out life-threatening causes first (Hypoxia, Hypoglycemia, Sepsis).
• Diagnosis: Use CAM criteria. Collateral history is non-negotiable.
• Treatment: Treat the underlying cause. Non-pharm interventions are FIRST line.
• Drugs to Avoid: Benzodiazepines (unless withdrawal), Anticholinergics (Gravol/Dimenhydrinate, Diphenhydramine), Meperidine.
• Post-discharge: Delirium can persist for months; arrange follow-up.

Sample Question

Clinical Scenario

A 79-year-old female is admitted to the internal medicine ward for the management of pyelonephritis. On the second night of admission, the nursing staff calls you because the patient has become agitated, is pulling at her IV lines, and is shouting that there are “spies in the room.” Her vital signs are: Temperature 37.8°C, HR 102 bpm, BP 135/85 mmHg, RR 20/min, O2 sat 96% on room air. A review of her chart shows she has mild Alzheimer’s dementia. She received a dose of dimenhydrinate for nausea earlier in the evening.

Question

Which one of the following is the most appropriate initial management step?

• A. Administer Lorazepam 1 mg IV
• B. Order a CT head to rule out intracranial hemorrhage
• C. Apply soft wrist restraints to prevent removal of IV lines
• D. Administer Haloperidol 5 mg IM
• E. Implement 1:1 constant observation and reorientation

Explanation

The correct answer is:

• E. Implement 1:1 constant observation and reorientation

Explanation: This patient is presenting with hyperactive delirium, likely superimposed on dementia (delirium superimposed on dementia). The precipitants include infection (pyelonephritis) and medication (dimenhydrinate, which has strong anticholinergic properties).

• Option E is correct. Canadian guidelines and Choosing Wisely Canada emphasize non-pharmacological interventions as the first line of management. 1:1 observation ensures safety (preventing IV pull-out) and allows for reorientation without the risks associated with physical or chemical restraints.
• Option A is incorrect. Benzodiazepines (Lorazepam) can worsen delirium and cause paradoxical agitation in the elderly. They are indicated primarily for alcohol/benzo withdrawal.
• Option B is incorrect. While CNS pathology is a cause, this patient has clear precipitants (infection, anticholinergic use). A CT head is not the initial step unless there are focal neurological signs or history of trauma.
• Option C is incorrect. Physical restraints often worsen agitation, increase the risk of injury, and prolong delirium. They are a last resort.
• Option D is incorrect. While antipsychotics may be used for severe agitation, the dose of 5 mg is excessively high for an elderly, antipsychotic-naive patient (start low, e.g., 0.25–0.5 mg). Furthermore, pharmacotherapy should only be considered after non-pharmacological measures fail or if there is immediate severe danger.

References

1. Canadian Coalition for Seniors’ Mental Health (CCSMH). (2014). Guideline on the Assessment and Treatment of Delirium in Older Adults. Link 
2. Choosing Wisely Canada. Geriatrics: Five Things Physicians and Patients Should Question. Link 
3. Inouye, S. K., et al. (1990). Clarifying confusion: the confusion assessment method. A new method for detection of delirium. Annals of Internal Medicine.
4. Medical Council of Canada. MCCQE Part I Objectives: Mental Health. Link 
5. Toronto Notes 2024. Geriatric Medicine & Psychiatry Sections.