What is a stroke?

What is a Stroke?

A stroke is an acute, sudden onset of focal neurological deficits caused by vascular injury to the central nervous system—either from blocked blood flow (ischemic) or bleeding (hemorrhagic)—and represents a medical emergency where every minute of delay results in the death of approximately 1.9 million brain cells. 1, 2

Types of Stroke

Stroke is not a single disease but encompasses distinct pathological types:

• Ischemic stroke accounts for approximately 85% of all strokes and results from complete occlusion of an artery, caused by small vessel disease, cardioembolism, or large artery atherothromboembolism 3
• Intracerebral hemorrhage represents approximately 15% of strokes worldwide, resulting from rupture of cerebral blood vessels with bleeding into brain tissue 3, 4
• Subarachnoid hemorrhage constitutes 9.7% of incident strokes, often caused by aneurysm rupture 4

Clinical Presentation

Cardinal Signs and Symptoms

The hallmark of stroke is awakening with or experiencing abrupt onset of focal neurological deficits 5. The most common presentations include:

• Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body 6, 1
• Speech disturbance including aphasia (impaired language production or comprehension) or difficulty understanding others 6, 1
• Visual disturbances such as sudden trouble seeing in one or both eyes, homonymous hemianopia, or diplopia 6, 1
• Sudden confusion or trouble understanding 6
• Sudden trouble walking, dizziness, loss of balance or coordination 6, 1
• Sudden severe headache with no known cause 6

Distinguishing Features by Stroke Type

Ischemic stroke typically develops suddenly with symptoms progressing over minutes to hours, presenting with focal neurological deficits corresponding to the affected brain region 1. Headache may be present but is less common than in hemorrhagic stroke 1.

Hemorrhagic stroke often presents with more severe headache that may have a thunderclap quality, is more likely to cause decreased level of consciousness, and commonly includes nausea and vomiting 1. Signs of increased intracranial pressure such as papilledema may be present 1.

Recognition Tools

The FAST (Face, Arms, Speech, Time) scale or Cincinnati Prehospital Stroke Scale is recommended to aid in recognition of acute stroke in adults, as these are the only tools validated for layperson administration 6. Both scales assess the same three physical examination items: face droop, arm weakness, and speech disturbance 6.

Time-Critical Nature

Stroke is a cerebral emergency requiring immediate EMS activation 6. The time-sensitivity cannot be overstated:

• Every minute of delay results in loss of 1.9 million brain cells, 13.8 billion synapses, and 12 km of axonal fibers 2
• Each hour without treatment causes the brain to age the equivalent of almost 3.6 years 2
• Fibrinolytic therapy administered within the first hours of symptom onset limits neurological injury and improves outcomes in selected patients with acute ischemic stroke 6

Epidemiology and Impact

Stroke remains a leading cause of death and severe, long-term disability:

• Nearly 800,000 people suffer stroke annually in the United States, with approximately 610,000 being first-time events 6
• Stroke is the second-leading cause of death globally (11.6% of total deaths) and the third-leading cause of death and disability combined 4
• Only 50% 5-year survival is observed in some clinical studies, with stroke severity at onset and patient age being the most important prognostic factors 7
• 20% of survivors require institutional care after 3 months, and 15-30% are permanently disabled 6

Risk Factors

The five leading risk factors contributing to stroke burden are:

• High systolic blood pressure (contributing to 55.5% of total stroke DALYs) 4
• High body-mass index (24.3% of stroke DALYs, and the fastest-growing risk factor) 4
• High fasting plasma glucose (20.2% of stroke DALYs) 4
• Ambient particulate matter pollution (20.1% of stroke DALYs) 4
• Smoking (17.6% of stroke DALYs) 4

Critical Action Steps

If stroke is suspected, the EMS system should be activated immediately 6. Community and professional education is essential to improve stroke recognition and early EMS activation 6. Patients at high risk for stroke, their family members, and basic life support providers should learn to recognize signs and symptoms and call EMS as soon as any signs are present 6.

EMS dispatchers should be trained to suspect stroke and rapidly dispatch emergency responders, and EMS personnel should perform out-of-hospital stroke assessment, establish time of symptom onset, provide cardiopulmonary support, and notify the receiving hospital 6.