Cerebrovascular Accident And Transient Ischemic Attack Stroke

Introduction

Cerebrovascular accidents (CVAs) and transient ischemic attacks (TIAs) are critical topics for MCCQE1 preparation, particularly in the context of Canadian healthcare. This comprehensive guide will cover essential concepts, Canadian guidelines, and provide practice materials to help you excel in your MCCQE1 exam.

Definitions and Epidemiology

Cerebrovascular Accident (Stroke)

A cerebrovascular accident, commonly known as a stroke, is a sudden loss of neurological function due to a disturbance in the blood supply to the brain. It can be either ischemic (due to lack of blood flow) or hemorrhagic (due to bleeding).

Transient Ischemic Attack (TIA)

A transient ischemic attack is a temporary episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction. Symptoms typically resolve within 24 hours.

Types of Stroke

Risk Factors

Understanding risk factors is crucial for MCCQE1 preparation, especially in the Canadian context:

1. Non-modifiable risk factors:

   • Age (risk doubles every decade after 55)
   • Sex (higher risk in males)
   • Family history
   • Ethnicity (higher risk in Indigenous and South Asian Canadians)

2. Modifiable risk factors:

   • Hypertension (leading risk factor in Canada)
   • Smoking
   • Diabetes
   • Atrial fibrillation
   • High cholesterol
   • Physical inactivity
   • Obesity
   • Excessive alcohol consumption

Clinical Presentation

Common Symptoms

• Sudden weakness or numbness (often on one side of the body)
• Confusion or difficulty speaking
• Vision problems
• Dizziness or loss of balance
• Severe headache (more common in hemorrhagic stroke)

Canadian Stroke Best Practices: FAST

The Heart and Stroke Foundation of Canada promotes the FAST approach for recognizing stroke symptoms:

• Face: Is it drooping?
• Arms: Can you raise both?
• Speech: Is it slurred or jumbled?
• Time: Call 9-1-1 right away

Diagnosis

Management

Acute Ischemic Stroke

1. Thrombolysis:

   • Alteplase (tPA) within 4.5 hours of symptom onset
   • Contraindications include recent major surgery, active bleeding, and uncontrolled hypertension

2. Endovascular Thrombectomy:

   • Consider for large vessel occlusions within 6 hours of symptom onset
   • May be considered up to 24 hours in select patients with salvageable brain tissue

3. Supportive Care:

   • Blood pressure management
   • Glucose control
   • Temperature regulation
   • Early mobilization

Hemorrhagic Stroke

1. Blood Pressure Control:

   • Target SBP <140 mmHg within first 6 hours

2. Reversal of Anticoagulation (if applicable):

   • Vitamin K, prothrombin complex concentrate, or fresh frozen plasma

3. Neurosurgical Intervention:

   • Consider for large hematomas or cerebellar hemorrhages

Secondary Prevention

• Antiplatelet therapy (e.g., ASA, clopidogrel)
• Anticoagulation for atrial fibrillation
• Statins for hyperlipidemia
• Blood pressure control
• Lifestyle modifications (smoking cessation, diet, exercise)

Canadian Guidelines

The Canadian Stroke Best Practice Recommendations provide evidence-based guidelines for stroke care in Canada. Key points include:

1. Hyperacute stroke management within 24 hours of symptom onset
2. Acute inpatient stroke care
3. Secondary prevention of stroke
4. Stroke rehabilitation
5. Stroke in young adults

Key Points to Remember for MCCQE1

• Know the FAST approach for stroke recognition
• Understand the time-sensitive nature of stroke treatment
• Be familiar with Canadian stroke statistics and risk factors
• Know the indications and contraindications for thrombolysis
• Understand the differences in management between ischemic and hemorrhagic stroke
• Be aware of the role of Stroke Units in Canadian healthcare
• Recognize the importance of secondary prevention strategies

Sample Question

A 68-year-old woman presents to the emergency department with sudden onset of right-sided weakness and difficulty speaking that began 2 hours ago. Her past medical history includes hypertension and type 2 diabetes. On examination, she has a right facial droop, right arm drift, and slurred speech. Her blood pressure is 180/95 mmHg. A non-contrast CT scan of the head shows no evidence of hemorrhage. Which of the following is the most appropriate next step in management?

• A. Administer aspirin 325 mg
• B. Start heparin infusion
• C. Perform MRI of the brain
• D. Administer intravenous alteplase
• E. Consult neurosurgery for possible thrombectomy

Explanation

The correct answer is:

• D. Administer intravenous alteplase

This patient presents with symptoms suggestive of an acute ischemic stroke within the 4.5-hour window for thrombolysis. The non-contrast CT scan has ruled out hemorrhage, which is a contraindication to thrombolysis. Given the patient's presentation and the absence of contraindications, intravenous alteplase (tPA) is the most appropriate next step in management.

Option A (aspirin) is not the best initial treatment for acute ischemic stroke when thrombolysis is an option. Option B (heparin) is not routinely recommended in acute ischemic stroke. Option C (MRI) would delay treatment unnecessarily. Option E (thrombectomy) may be considered, but intravenous thrombolysis should be administered first if eligible.

References

1. Heart and Stroke Foundation of Canada. (2021). Stroke Report 2021. Retrieved from https://www.heartandstroke.ca/stroke/what-is-stroke/stroke-facts (opens in a new tab)

2. Boulanger, J. M., Lindsay, M. P., Gubitz, G., Smith, E. E., Stotts, G., Foley, N., ... & Butcher, K. (2018). Canadian stroke best practice recommendations for acute stroke management: prehospital, emergency department, and acute inpatient stroke care, update 2018. International Journal of Stroke, 13(9), 949-984.

3. Casaubon, L. K., Boulanger, J. M., Blacquiere, D., Boucher, S., Brown, K., Goddard, T., ... & Lindsay, M. P. (2015). Canadian stroke best practice recommendations: hyperacute stroke care guidelines, update 2015. International Journal of Stroke, 10(6), 924-940.

4. Powers, W. J., Rabinstein, A. A., Ackerson, T., Adeoye, O. M., Bambakidis, N. C., Becker, K., ... & Tirschwell, D. L. (2019). Guidelines for the early management of patients with acute ischemic stroke: 2019 update to the 2018 guidelines for the early management of acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke, 50(12), e344-e418.

5. Coutts, S. B., Wein, T. H., Lindsay, M. P., Buck, B., Cote, R., Ellis, P., ... & Gubitz, G. (2015). Canadian stroke best practice recommendations: secondary prevention of stroke guidelines, update 2014. International Journal of Stroke, 10(3), 282-291.