Stroke

Types of Stroke

There are three main types of stroke, each involving a different mechanism of blood flow disruption:

1. Ischemic Stroke (Most Common):
   • Cause: Ischemic stroke occurs when a blood clot blocks or narrows an artery supplying blood to the brain, causing a reduction in blood flow (ischemia).
   • Types of Ischemic Stroke:
     • Thrombotic Stroke: This type is caused by a blood clot (thrombus) that forms in one of the arteries supplying blood to the brain. This usually occurs in the context of atherosclerosis (narrowing and hardening of the arteries due to fatty deposits).
     • Embolic Stroke: This occurs when a blood clot or other debris forms elsewhere in the body (usually the heart) and travels through the bloodstream to the brain. This is called an embolus.
   • Risk Factors: High blood pressure, diabetes, high cholesterol, smoking, atrial fibrillation (an irregular heartbeat), and heart disease are common risk factors.
   • Symptoms: Symptoms of an ischemic stroke typically come on suddenly and may include:
     • Sudden numbness or weakness in the face, arm, or leg (especially on one side of the body).
     • Difficulty speaking or understanding speech.
     • Sudden confusion or trouble with vision in one or both eyes.
     • Trouble walking, dizziness, or loss of balance.
2. Hemorrhagic Stroke:
   • Cause: Hemorrhagic stroke occurs when a blood vessel in the brain ruptures, causing bleeding (hemorrhage) within the brain tissue or the spaces surrounding the brain.
   • Types of Hemorrhagic Stroke:
     • Intracerebral Hemorrhage: This is the most common type of hemorrhagic stroke, occurring when a blood vessel inside the brain ruptures and spills blood into the surrounding brain tissue.
     • Subarachnoid Hemorrhage: This occurs when there is bleeding in the space between the brain and the thin tissues covering it (the subarachnoid space). A common cause is the bursting of an aneurysm (a weakened, bulging area in a blood vessel wall).
   • Risk Factors: High blood pressure (hypertension), aneurysms, arteriovenous malformations (AVMs), head injury, blood thinners, and excessive alcohol consumption.
   • Symptoms: Symptoms of hemorrhagic stroke can include:
     • Sudden, severe headache (often described as the “worst headache of your life”).
     • Nausea and vomiting.
     • Sudden weakness or numbness, often on one side of the body.
     • Difficulty speaking or understanding speech.
     • Sudden vision changes or loss of coordination.
     • Seizures (in some cases).
3. Transient Ischemic Attack (TIA):
   • Cause: Often called a “mini-stroke,” a TIA is a temporary blockage or reduction in blood flow to part of the brain that causes stroke-like symptoms for a short period. TIAs are typically brief (lasting minutes to hours) and do not result in permanent brain damage.
   • Risk Factors: TIAs have the same risk factors as ischemic stroke and may be a warning sign of an impending stroke.
   • Symptoms: TIA symptoms are similar to those of ischemic stroke but resolve completely within a few hours. Immediate medical attention is crucial because TIAs are strong indicators that a full stroke may occur in the near future.

Symptoms of Stroke

Stroke symptoms can vary depending on the type of stroke and the area of the brain affected. Common signs of a stroke include:

• Sudden numbness or weakness: Especially on one side of the body (e.g., face, arm, or leg).
• Sudden confusion or trouble speaking: Difficulty understanding speech or speaking clearly.
• Sudden trouble seeing: Loss or blurriness of vision in one or both eyes.
• Sudden trouble walking: Dizziness, loss of balance, or lack of coordination.
• Sudden severe headache: Often described as the worst headache of one’s life, especially in the case of a hemorrhagic stroke.

The American Heart Association uses the FAST acronym to help recognize stroke symptoms quickly:

• F: Face drooping – Does one side of the face droop or is it numb? Ask the person to smile.
• A: Arm weakness – Is one arm weak or numb? Ask the person to raise both arms.
• S: Speech difficulty – Is speech slurred, or is the person unable to speak or hard to understand? Ask the person to repeat a simple sentence.
• T: Time to call 911 – If you observe any of these signs, even if they go away, call emergency services immediately.

Causes and Risk Factors

The causes of stroke are related to factors that either disrupt blood flow to the brain (ischemic stroke) or cause bleeding in the brain (hemorrhagic stroke). Common risk factors include:

1. High Blood Pressure (Hypertension): The leading cause of both ischemic and hemorrhagic stroke.
2. Atherosclerosis: Hardening or narrowing of the arteries due to plaque buildup increases the risk of ischemic stroke.
3. Heart Disease: Conditions like atrial fibrillation (irregular heartbeat) or heart failure can increase the risk of stroke, particularly embolic strokes.
4. Diabetes: Increases the risk of stroke by contributing to high blood pressure, high cholesterol, and artery damage.
5. Smoking: Damages blood vessels and accelerates atherosclerosis, increasing stroke risk.
6. Excessive Alcohol Use: Chronic heavy drinking increases the risk of both ischemic and hemorrhagic stroke.
7. Obesity: A risk factor for many conditions that increase stroke risk, including high blood pressure, high cholesterol, and diabetes.
8. Family History and Genetics: A family history of stroke or other cardiovascular diseases increases the risk of stroke.
9. Age: Stroke risk increases with age, particularly after age 55.
10. Gender: Men have a higher risk of stroke at a younger age, while women have a higher risk of stroke after age 55.
11. Physical Inactivity: A sedentary lifestyle increases stroke risk.
12. Previous TIA or Stroke: A history of stroke or TIA significantly increases the risk of having another stroke.

Diagnosis of Stroke

Early diagnosis of stroke is essential for effective treatment. Methods to diagnose stroke include:

1. Physical Examination: A doctor will check for signs of stroke, such as weakness, numbness, difficulty speaking, or trouble walking.
2. Imaging Tests:
   • CT Scan: A CT scan (computed tomography) is often the first test done to quickly identify whether the stroke is ischemic (blocked blood vessel) or hemorrhagic (bleeding).
   • MRI: Magnetic resonance imaging (MRI) provides a more detailed view of brain tissue and can help detect ischemic strokes earlier than CT scans.
3. Blood Tests: These may be used to check for clotting disorders, blood sugar levels, or infection.
4. Electrocardiogram (ECG): This test checks for irregular heart rhythms (such as atrial fibrillation), which can increase the risk of stroke.
5. Carotid Ultrasound: This test examines the blood flow in the carotid arteries to check for narrowing or blockages.
6. Cerebral Angiography: In some cases, an angiogram is used to visualize blood vessels in the brain and detect blockages or aneurysms.

Treatment of Stroke

The treatment of stroke depends on the type of stroke, its severity, and the timing of treatment. The goal is to restore blood flow to the brain or stop the bleeding to prevent further brain damage.

1. Ischemic Stroke:
   • Clot-Busting Medications (Thrombolytics): Tissue Plasminogen Activator (tPA) is the most common clot-busting drug used to treat ischemic stroke. It must be administered within 3 to 4.5 hours of symptom onset for maximum effectiveness.
   • Mechanical Thrombectomy: A procedure in which a clot is physically removed from a blocked artery in the brain. This is typically done within 6-24 hours of symptom onset, depending on the case.
   • Antiplatelet Drugs: Aspirin or other antiplatelet medications may be given to prevent further clot formation.
   • Anticoagulants: In cases of atrial fibrillation or other conditions that increase clotting risk, blood thinners may be prescribed.
2. Hemorrhagic Stroke:
   • Surgical Intervention: Surgery may be required to repair a ruptured blood vessel or to relieve pressure in the brain caused by bleeding.
   • Medication: Medications may be given to control blood pressure and prevent further bleeding.
   • Coiling or Clipping of Aneurysms: In cases of subarachnoid hemorrhage caused by a brain aneurysm, a procedure may be done to stop the bleeding by either coiling the aneurysm or placing a clip on it.
3. Post-Stroke Rehabilitation:
   • Rehabilitation is a crucial part of stroke recovery and may include physical therapy, speech therapy, occupational therapy, and psychological support.
   • Rehabilitation helps patients regain lost functions, improve mobility, and adjust to any permanent disabilities caused by the stroke.

Prevention of Stroke

Preventing stroke involves addressing the underlying risk factors:

• Control High Blood Pressure: Monitor and manage blood pressure through lifestyle changes and medications.
• Manage Diabetes: Keep blood sugar levels under control.
• Cholesterol Management: Maintain healthy cholesterol levels through diet, exercise, and medication if necessary.
• Quit Smoking: Smoking cessation greatly reduces stroke risk.
• Limit Alcohol Intake: Limit alcohol consumption to moderate levels.
• Exercise Regularly: Engage in regular physical activity to improve cardiovascular health.
• Dietary Modifications: Eat a heart-healthy diet rich in fruits, vegetables, whole grains, and lean proteins.
• Regular Medical Checkups: Regular checkups and screenings can help detect and treat risk factors such as high blood pressure or atrial fibrillation before they cause a stroke.

Prognosis

The prognosis after a stroke depends on various factors, including the type, severity, and location of the stroke, as well as the speed of medical intervention. Some people recover fully, while others may experience long-term disability. Early treatment and rehabilitation can significantly improve the chances of recovery. Prompt medical attention is critical for reducing the long-term impact of a stroke.