What Is a Stroke? Understanding Types, Symptoms, and Prevention

Stroke, often referred to as a “brain attack,” is a serious medical emergency that occurs when the blood supply to part of the brain is interrupted or severely reduced. Deprived of oxygen and nutrients, brain cells begin to die within minutes. This can lead to lasting brain damage, long-term disability, or even death. Understanding what a stroke is, recognizing its symptoms, and knowing the risk factors are crucial for timely intervention and prevention.

There are primarily two main types of stroke: ischemic stroke and hemorrhagic stroke. Both types disrupt the brain’s blood flow, but they do so in different ways. Prompt medical attention is vital for both kinds to minimize brain damage and improve the chances of recovery. Recognizing the signs and acting FAST can significantly improve outcomes for individuals experiencing a stroke.

Types of Stroke: Ischemic and Hemorrhagic

Strokes are broadly classified into ischemic and hemorrhagic strokes, each requiring different treatment approaches. Ischemic strokes are far more common, accounting for about 85% of all stroke cases.

Ischemic Stroke: Blockage of Blood Flow

An ischemic stroke happens when an artery that carries blood to the brain becomes blocked or narrowed, significantly reducing or stopping blood flow. This blockage is most often caused by a blood clot. These clots can form in two main ways:

Thrombotic Stroke: A thrombus, or blood clot, develops within an artery in the brain, often in arteries already narrowed by atherosclerosis. Atherosclerosis is a condition where plaque, made up of fat, cholesterol, and other substances, builds up on the inner walls of arteries.
Embolic Stroke: An embolus, which is a blood clot or other debris, travels from another part of the body (often the heart or upper chest arteries) to the brain and lodges in a narrower brain artery, causing a blockage.

Regardless of the origin, the result is the same: a part of the brain is deprived of the oxygen and nutrients it needs to function, leading to potential brain cell damage. Conditions like atrial fibrillation, where the heart beats irregularly, can increase the risk of embolic strokes because clots can form in the heart and travel to the brain.

Hemorrhagic Stroke: Bleeding in the Brain

Hemorrhagic stroke occurs when a blood vessel in the brain ruptures and bleeds. This bleeding can happen in two main ways:

Intracerebral Hemorrhage: Bleeding occurs within the brain tissue itself. High blood pressure is the most common cause, as it can weaken arteries in the brain over time, making them more prone to rupture.
Subarachnoid Hemorrhage: Bleeding occurs in the space between the brain and the surrounding membrane (subarachnoid space). This type is often caused by a ruptured aneurysm, which is a bulge or weak spot in a blood vessel wall. Trauma, arteriovenous malformations (AVMs), and certain medications can also lead to hemorrhagic strokes.

The blood from a hemorrhagic stroke puts pressure on the surrounding brain tissue, damaging brain cells. This increased pressure, along with the lack of blood flow beyond the rupture point, contributes to the neurological damage associated with hemorrhagic strokes.

Transient Ischemic Attack (TIA): A Warning Sign

A transient ischemic attack (TIA), often called a “mini-stroke,” is a temporary disruption of blood flow to the brain. The symptoms of a TIA are similar to those of a full stroke, but they are temporary, usually lasting from a few minutes to less than an hour, and resolve completely without causing permanent brain damage.

TIAs are critical warning signs that a full stroke may be imminent. They indicate that there is an underlying problem with blood flow to the brain, such as narrowed arteries. Experiencing a TIA significantly increases the risk of having a major stroke in the future. It is crucial to seek immediate medical attention after a TIA to identify the cause and begin preventive treatment.

Recognizing Stroke: Act FAST

Recognizing the symptoms of a stroke quickly is critical because prompt treatment can significantly reduce brain damage and the potential for long-term disability. The acronym FAST is an easy way to remember the most common warning signs of a stroke:

F – Face Drooping: Ask the person to smile. Does one side of the face droop or look uneven? Facial weakness or drooping on one side is a hallmark sign of stroke.
A – Arm Weakness: Ask the person to raise both arms. Does one arm drift downward, or is the person unable to raise one arm at all? Weakness or numbness in one arm (or leg) is a common stroke symptom, often affecting one side of the body.
S – Speech Difficulty: Ask the person to repeat a simple sentence, like “The sky is blue.” Is their speech slurred, difficult to understand, or are they unable to speak at all? Stroke can affect the speech centers of the brain, leading to confusion, difficulty finding words, or slurred speech.
T – Time to Call Emergency Services: If you observe any of these signs, even if they are mild or go away quickly, time is critical. Call 911 or your local emergency number immediately. Do not wait to see if symptoms improve. Every minute counts in stroke treatment.

Beyond the FAST symptoms, other stroke symptoms can include:

Sudden numbness or weakness: Especially on one side of the body, affecting the face, arm, or leg.
Trouble seeing in one or both eyes: This can include blurred vision, double vision, or sudden vision loss in one eye.
Sudden, severe headache: Especially if it comes on suddenly and is unlike previous headaches. This is more common in hemorrhagic strokes.
Dizziness or loss of balance: Sudden unsteadiness, difficulty walking, or loss of coordination.
Confusion or trouble understanding: Difficulty understanding spoken words or sudden confusion.

It’s important to remember that stroke symptoms appear suddenly. If you or someone you know experiences any of these symptoms, seek immediate medical attention, even if the symptoms seem to come and go.

Stroke Causes and Risk Factors: Understanding Your Vulnerability

While a stroke can happen to anyone at any age, certain factors can significantly increase your risk. Understanding these risk factors empowers you to take proactive steps toward prevention.

The immediate causes of stroke are, as discussed, the blockage of an artery (ischemic stroke) or the rupture of a blood vessel (hemorrhagic stroke). However, several underlying conditions and lifestyle choices contribute to these events.

Lifestyle Risk Factors: Controllable Aspects

Many stroke risk factors are related to lifestyle choices that can be modified:

High Blood Pressure (Hypertension): This is the leading risk factor for stroke. High blood pressure puts extra strain on blood vessels, making them more likely to become damaged or rupture.
Smoking: Smoking damages blood vessels, increases blood clot formation, and raises blood pressure, significantly increasing stroke risk. Exposure to secondhand smoke also elevates risk.
High Cholesterol: High levels of LDL (“bad”) cholesterol contribute to the buildup of plaque in arteries (atherosclerosis), increasing the risk of ischemic stroke.
Unhealthy Diet: Diets high in saturated and trans fats, cholesterol, and sodium can contribute to high blood pressure, high cholesterol, and obesity, all stroke risk factors.
Physical Inactivity: Lack of regular exercise contributes to obesity, high blood pressure, high cholesterol, and diabetes, increasing stroke risk.
Obesity and Overweight: Excess weight is linked to high blood pressure, diabetes, high cholesterol, and sleep apnea, all of which elevate stroke risk.
Heavy Alcohol Consumption: Excessive alcohol intake can raise blood pressure and increase the risk of both ischemic and hemorrhagic strokes.
Illicit Drug Use: Drugs like cocaine and methamphetamine can dramatically increase blood pressure and lead to stroke.

Medical Risk Factors: Conditions to Manage

Certain medical conditions significantly increase stroke risk and require medical management:

Diabetes: Diabetes damages blood vessels and increases the risk of atherosclerosis and blood clots, raising the risk of ischemic stroke.
Cardiovascular Disease: Conditions like coronary artery disease, heart failure, atrial fibrillation, and carotid artery disease significantly increase stroke risk by affecting blood flow and clot formation.
Obstructive Sleep Apnea (OSA): OSA, a condition where breathing repeatedly stops and starts during sleep, is linked to high blood pressure, heart disease, and stroke.
Previous Stroke or TIA: Having had a stroke or TIA significantly increases the risk of future strokes.
Family History of Stroke: A family history of stroke suggests a genetic predisposition and shared lifestyle factors that can increase individual risk.
COVID-19 Infection: Emerging research suggests that COVID-19 infection may temporarily increase the risk of ischemic stroke, although more research is ongoing.

Non-Modifiable Risk Factors: Inherent Predispositions

Some stroke risk factors are inherent and cannot be changed, but awareness is still important:

Age: The risk of stroke increases significantly with age, doubling every decade after age 55.
Race and Ethnicity: African Americans and Hispanics have a higher stroke risk compared to Caucasians. This may be due to higher rates of conditions like high blood pressure and diabetes in these populations.
Sex: Men have a slightly higher risk of stroke overall, but women are often older when they have strokes and have a higher stroke mortality rate.
Hormones: Hormone replacement therapy and birth control pills containing estrogen can slightly increase stroke risk, particularly in women who smoke or have other risk factors.

Complications of Stroke: Potential Long-Term Effects

The complications of a stroke vary widely depending on the severity of the stroke, the area of the brain affected, and how quickly treatment is received. Stroke can lead to temporary or permanent disabilities, affecting various aspects of life.

Common stroke complications include:

Paralysis or Muscle Weakness: Stroke often causes paralysis or weakness on one side of the body (hemiparesis), affecting the face, arm, and leg. This can impact mobility, balance, and coordination.
Speech and Language Difficulties (Aphasia): Stroke can damage brain areas controlling language, leading to difficulties speaking (expressive aphasia), understanding speech (receptive aphasia), reading, and writing.
Swallowing Difficulties (Dysphagia): Weakness in the muscles of the mouth and throat can make swallowing difficult, increasing the risk of choking and aspiration pneumonia.
Memory Loss and Cognitive Difficulties: Stroke can affect memory, attention, learning, reasoning, judgment, and problem-solving abilities.
Emotional and Behavioral Changes: Stroke survivors may experience emotional lability (rapid mood swings), depression, anxiety, irritability, and personality changes.
Pain: Pain, numbness, or tingling sensations can occur in the parts of the body affected by stroke, often due to damage to sensory pathways in the brain.
Bowel and Bladder Control Issues: Stroke can disrupt nerve pathways that control bowel and bladder function, leading to incontinence.
Fatigue: Post-stroke fatigue is common and can significantly impact daily life.

Rehabilitation plays a crucial role in helping stroke survivors recover and manage these complications. This may include physical therapy, occupational therapy, speech therapy, and psychological support.

Stroke Prevention: Taking Control of Your Health

Preventing a stroke is often possible by addressing modifiable risk factors and adopting a healthy lifestyle. Even if you have already had a stroke or TIA, these measures can help reduce your risk of future events.

Key stroke prevention strategies include:

Manage High Blood Pressure: Regularly monitor blood pressure and work with your doctor to keep it within a healthy range through lifestyle changes and medication if needed.
Control Cholesterol: Eat a diet low in saturated and trans fats and cholesterol, and consider cholesterol-lowering medication if lifestyle changes are insufficient.
Quit Smoking: Quitting smoking is one of the most effective ways to reduce stroke risk. Seek support from healthcare professionals and cessation programs.
Manage Diabetes: Control blood sugar levels through diet, exercise, and medication as prescribed by your doctor.
Maintain a Healthy Weight: Achieve and maintain a healthy weight through a balanced diet and regular physical activity.
Eat a Healthy Diet: Emphasize fruits, vegetables, whole grains, and lean protein. Limit processed foods, sugary drinks, and unhealthy fats. The Mediterranean diet is often recommended.
Engage in Regular Exercise: Aim for at least 150 minutes of moderate-intensity aerobic exercise per week.
Limit Alcohol Consumption: If you drink alcohol, do so in moderation (up to one drink per day for women and up to two drinks per day for men).
Treat Obstructive Sleep Apnea: If you suspect you have OSA, get tested and treated. Treatment often involves using a CPAP machine.
Avoid Illicit Drug Use: Refrain from using illicit drugs like cocaine and methamphetamine.

In addition to lifestyle changes, your doctor may recommend preventive medications, especially if you have had a stroke or TIA or have other high-risk conditions:

Antiplatelet Medications: Aspirin, clopidogrel, and ticagrelor help prevent blood clots from forming.
Anticoagulant Medications: Warfarin, dabigatran, rivaroxaban, apixaban, and edoxaban are blood thinners used to prevent clots, especially in people with atrial fibrillation.

Understanding what a stroke is, recognizing its symptoms, and knowing your risk factors are essential steps in protecting your brain health. By adopting a healthy lifestyle and working closely with your healthcare provider, you can significantly reduce your risk of stroke and its potentially devastating consequences. Remember, acting FAST at the first sign of stroke symptoms can make a life-saving difference.

By Mayo Clinic Staff

Stroke care at Mayo Clinic

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Dec. 13, 2024

References

Walls RM, et al., eds. Stroke. In: Rosen’s Emergency Medicine: Concepts and Clinical Practice. 10th ed. Elsevier; 2023. https://www.clinicalkey.com. Accessed Sept. 13, 2023.
Ferri FF. Ferri’s Clinical Advisor 2024. Elsevier; 2024. https://www.clinicalkey.com. Accessed Sept. 13, 2023.
Patients and caregivers. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/public-education/know-stroke/patients-and-caregivers#. Accessed Sept. 13, 2023.
Stroke. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health-topics/stroke. Accessed Sept. 13, 2023.
Oliveira-Filho J, et al. Initial assessment and management of acute stroke. https://www.uptodate.com/contents/search. Accessed Sept. 13, 2023.
About stroke. Centers for Disease Control and Prevention. https://www.cdc.gov/stroke/healthy_living.htm. Accessed Sept. 13, 2023.
Effects of stroke. American Stroke Association. https://www.stroke.org/en/about-stroke/effects-of-stroke. Accessed Sept. 13, 2023.
Rehab therapy after a stroke. American Stroke Association. https://www.stroke.org/en/life-after-stroke/stroke-rehab/rehab-therapy-after-a-stroke. Accessed Sept. 13, 2023.
Arteriovenous malformations (AVMs). National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/arteriovenous-malformations-avms?search-term=arterial#. Accessed Oct. 2, 2023.
Cerebral aneurysms. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/disorders/patient-caregiver-education/fact-sheets/cerebral-aneurysms-fact-sheet. Accessed Sept. 13, 2023.
Transient ischemic attack. Merck Manual Professional Version. https://www.merckmanuals.com/professional/neurologic-disorders/stroke/transient-ischemic-attack-tia?query=transient%20ischemic%20attack#. Accessed Sept. 13, 2023.
Stroke. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Post-Stroke-Rehabilitation-Fact-Sheet. Accessed Sept. 13, 2023.
Rose NS, et al. Overview of secondary prevention of ischemic stroke. https://www.uptodate.com/contents/search. Accessed Sept. 13, 2023.
Prevent stroke: What you can do. Centers for Disease Control and Prevention. https://www.cdc.gov/stroke/prevention.htm#print. Accessed Sept. 13, 2023.
Know your risk for stroke. Centers for Disease Control and Prevention. https://www.cdc.gov/stroke/risk_factors.htm#. Accessed Oct. 2, 2023.
Powers WJ, et al. 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. 2019; doi:10.1161/STR.0000000000000211.
Papadakis MA, et al., eds. Quick Medical Diagnosis & Treatment 2023. McGraw Hill; 2023. https://accessmedicine.mhmedical.com. Accessed Sept. 13, 2023.
Tsao CW, et al. Heart disease and stroke statistics — 2023 update: A report from the American Heart Association. Circulation. 2023; doi:10.1161/CIR.0000000000001123.
Grotta JC, et al., eds. Stroke: Pathophysiology, Diagnosis, and Management. 7th ed. Elsevier, 2022. https://www.clinicalkey.com. Accessed Sept. 15, 2023.
Suppah M, et al. An evidence-based approach to anticoagulation therapy comparing direct oral anticoagulants and vitamin K antagonists in patients with atrial fibrillation and bioprosthetic valves: A systematic review, meta-analysis and network meta-analysis. American Journal of Cardiology. 2023; doi:10.1016/j.amjcard.2023.07.141.
Tyagi K, et al. Neurological manifestations of SARS-CoV-2: Complexity, mechanism and associated disorders. European Journal of Medical Research. 2023; doi:10.1186/s40001-023-01293-2.
Siegler JE, et al. Cerebrovascular disease in COVID-19. Viruses. 2023; doi:10.3390/v15071598.
Lombardo M, et al. Health effects of red wine consumption: A narrative review of an issue that still deserves debate. Nutrients. 2023; doi:10.3390/nu15081921.
Jim J. Complications of carotid endarterectomy. https://www.uptodate.com/contents/search. Accessed Oct. 2, 2023.
Van Nimwegan D, et al. Interventions for improving psychosocial well-being after stroke: A systematic review. International Journal of Nursing Studies. 2023; doi:10.1016/j.ijnurstu.2023.104492.
Hasan TF, et al. Diagnosis and management of acute ischemic stroke. Mayo Clinic Proceedings. 2018; doi:10.1016/j.mayocp.2018.02.013.
Ami TR. Allscripts EPSi. Mayo Clinic. Sept. 4, 2023.
Barrett KM, et al. Ambulance-based assessment of NIH stroke scale with telemedicine: A feasibility pilot study. Journal of Telemedicine and Telecare. 2017; doi:10.1177/1357633X16648490.
Sener U, et al. Ischemic stroke in patients with malignancy. Mayo Clinic Proceedings. 2022; doi:10.1016/j.mayocp.2022.09.003.
Quality check. The Joint Commission. https://www.qualitycheck.org/search/?keyword=mayo%20clinic. Accessed Oct. 4, 2023.
Quality care you can trust. American Heart Association. https://www.heart.org/en/professional/quality-improvement/hospital-maps. Accessed Oct. 4, 2023.
Attig JM. Allscripts EPSi. Mayo Clinic. Oct. 9, 2023.
How much physical activity do you need? American Heart Association. https://www.heart.org/en/healthy-living/fitness/fitness-basics/aha-recs-for-physical-activity-infographic. Accessed Oct. 12, 2023.
Graff-Radford J (expert opinion). Mayo Clinic. Oct. 11, 2023.
Healthcare. DNV Healthcare USA, Inc. https://www.dnvhealthcareportal.com/hospitals?search_type=and&q=mayo+clinic&c=&c=20806&c=&c=&prSubmit=Search. Accessed Nov. 1, 2023.