What are the causes of acute stroke?

Causes of Acute Stroke

Acute stroke is primarily classified into two major types: ischemic strokes (85% of all strokes) caused by blocked blood vessels to the brain, and hemorrhagic strokes (15%) caused by ruptured vessels in and around the brain. 1, 2

Ischemic Stroke Causes (85% of all strokes)

• Large-vessel atherosclerosis (20%): Atherosclerotic disease affecting extracranial or intracranial segments of carotid or vertebrobasilar arteries 1

• Small vessel disease/Penetrating artery disease (25%): Causes lacunar or subcortical strokes through arteriolosclerosis of small vessels 1

• Cardiogenic embolism (20%): Most frequently from atrial fibrillation, where blood clots form in the heart and travel to the brain 1

• Cryptogenic stroke (30%): Strokes for which the exact cause remains unknown despite thorough evaluation 1

• Other causes: Particularly in younger patients (<50 years), these may include:

  • Arterial dissection (especially extracranial) 2
  • Hypercoagulable states 3
  • Vasculitis 4

Hemorrhagic Stroke Causes (15% of all strokes)

Intracerebral Hemorrhage (ICH) (10% of all strokes)

• Hypertension: The number one cause, particularly for deep hemorrhages in basal ganglia and brainstem 1
• Cerebral amyloid angiopathy: Primary cause of lobar hemorrhages 2
• Bleeding disorders 1
• Vascular malformations 1, 2
• Excessive alcohol use/abuse 1
• Liver dysfunction 1
• Aging 1

Subarachnoid Hemorrhage (SAH) (3% of all strokes)

• Ruptured cerebral aneurysm: Primary cause 1
• Arteriovenous malformations 2
• Venous sinus thrombosis 2

Risk Factors for Stroke

Major Modifiable Risk Factors

• Hypertension: Most important modifiable risk factor across all stroke types 2, 5
• High body-mass index: Fastest growing risk factor between 1990-2019 5
• High fasting plasma glucose/Diabetes 5
• Ambient particulate matter pollution 5
• Smoking 5
• Atrial fibrillation: Particularly for cardioembolic stroke 1

Non-modifiable Risk Factors

• Age: Risk increases with advancing age 1, 5
• Sex: Women experience 60,000 more strokes than men annually 1
• Race/Ethnicity:
  • American Indian/Alaskan Native persons have highest prevalence (6.7%) 1
  • Black men and women have twice the prevalence of stroke as whites 1
  • Higher prevalence in Hispanic/Latino men (3.1%) compared to non-Hispanic white men (2.4%) 1

Clinical Considerations

• Acute ischemic stroke due to large-vessel occlusion is particularly severe and life-threatening 1
• Rapid identification and treatment are essential as every 30-minute delay in recanalization decreases the chance of good functional outcome by 8-14% 1
• Treatment options for ischemic stroke include intravenous thrombolysis (alteplase or tenecteplase) and endovascular therapy for large vessel occlusions 1, 4
• For hemorrhagic stroke, immediate management includes blood pressure control, reversal of anticoagulation if applicable, and consideration for neurosurgical intervention 1, 4

Global Burden

• Stroke is the second leading cause of death worldwide and third-leading cause of death and disability combined 5
• Mortality rates are 3.6 times higher in low-income countries compared to high-income countries 5
• The absolute number of strokes increased by 70% from 1990 to 2019, though age-standardized rates have decreased 5