Makindo Medical Notes

Related Subjects: |Acute Stroke Assessment (ROSIER&NIHSS) |Atrial Fibrillation |Atrial Myxoma |Causes of Stroke |Ischaemic Stroke |Cancer and Stroke |Cardioembolic stroke |CT Basics for Stroke |Endocarditis and Stroke |Haemorrhagic Stroke |Stroke Thrombolysis |Brain Herniation syndromes |Haemorrhagic stroke |Traumatic Head/Brain Injury |Acute Hydrocephalus |Epidural Haematoma |Subdural haematoma |Basic Neuroscience |Basal Ganglia |Apraxia |Cerebral Angiography and Perfusion

Introduction

• Diagnosing the cause of a stroke can be like solving a mystery, similar to the detective work of Sherlock Holmes. A skilled stroke physician not only diagnoses stroke but also investigates its cause to prevent future occurrences. This means listening for carotid bruits, checking for atrial fibrillation, looking for signs like Horner's syndrome that suggest carotid dissection, or listening for a heart murmur indicative of endocarditis.
• The role of the stroke physician is to compile a list of likely causes based on the type of stroke, patient history, and examination findings. Using neuroscience knowledge, imaging, and targeted investigations—along with critical thinking and Bayesian analysis—helps identify the true cause. It’s crucial to avoid hastily attributing the stroke to an unrelated finding, like a patent foramen ovale (PFO), without proper analysis.
• For instance, finding a PFO doesn't necessarily mean it caused the stroke. It’s important to consider the full clinical context before making conclusions. In some cases, despite thorough investigation, no specific cause can be identified; this is termed a *cryptogenic stroke*. Accepting uncertainty is better than treating an innocent bystander.

Challenges for a Stroke Physician

• Accurately diagnose a stroke and distinguish it from stroke mimics.
• Determine the likely cause of the stroke in each individual patient.
• Use this information to create a tailored strategy to prevent further strokes.
• Communicate the findings and plan clearly to patients and their families.
• Avoid unnecessary, misleading, or potentially harmful tests while focusing on those with the highest diagnostic yield.

Reasoning

• In some cases, determining the cause of a stroke is straightforward—an ECG might reveal atrial fibrillation, or an echocardiogram may show a dilated left atrium. But complexity arises when multiple possible causes coexist. For example, an elderly patient might have both atrial fibrillation and a significant carotid stenosis. Which one caused the stroke? Should treatment focus on anticoagulation, carotid surgery, or both? Each decision involves weighing risks and benefits.
• Understanding stroke causes is essential because most strokes (around 80%) are ischaemic, caused by blockages, while others are due to spontaneous intracranial haemorrhage (15%) or subarachnoid haemorrhage (5%). Each category has numerous potential mechanisms, and sometimes multiple factors work together to cause a stroke. For example, a young woman who smokes, uses oral contraceptives, and has a history of migraines might face an increased risk of stroke due to the additive effects of these factors.
• Strokes can often result from a combination of risk factors and behaviors. Understanding the contributing elements allows for better prevention strategies, such as counseling a patient to avoid dehydration and excessive alcohol after a PFO-related stroke.

Aetiologies of Ischaemic Stroke

• Cardioembolic Stroke
• Artery-to-Artery Embolism
• Atrial Fibrillation
• Ischaemic Stroke
• Small Vessel Disease
• Hypertension
• Structural Cardiac Disease
• Infective Endocarditis
• Patent Foramen Ovale (PFO)
• Paradoxical Embolism
• Cerebral Venous Thrombosis
• Carotid Dissection
• Vertebral Dissection
• Fabry's Disease
• CADASIL/CARASIL
• Thrombophilias
• Sickle Cell Disease
• Giant Cell Arteritis
• Reversible Cerebral Vasoconstriction Syndrome (RCVS)

Aetiologies of Haemorrhagic Stroke

• Hypertension
• Cerebral Amyloid Angiopathy
• Vascular Anomalies
• Cerebral Venous Thrombosis

Mechanisms of Ischaemic Stroke

• In situ arterial thrombosis
• In situ venous thrombosis
• Embolism: artery-to-artery (e.g., from a ruptured plaque)
• Embolism: cardioembolic or paradoxical emboli
• Low flow: shock or hypotension causing watershed infarcts

Pathological Causes of Ischaemic Stroke

Miscellaneous Causes

Mechanisms of Haemorrhagic Stroke

Pathological Causes of Haemorrhagic Stroke

Causes of Subarachnoid Haemorrhage

• Saccular Aneurysm
• Arteriovenous Malformation
• Idiopathic/Perimesencephalic
• Trauma
• Anticoagulants
• Reversible Cerebral Vasoconstriction Syndrome (RCVS)
• Intracranial Dissection

Monogenic Causes of Stroke

• CADASIL
• CARASIL
• MELAS (Mitochondrial Disorder)
• Sickle Cell Disease