Ischemic Stroke: Causes, Risks, and Diagnosis

• Ischemic stroke occurs when blood supply to part of the brain is interrupted or reduced, preventing brain tissue from getting oxygen and nutrients

Causes and Risk Factors

• Thrombotic stroke: Caused by a blood clot that forms in the arteries supplying the brain
• Embolic stroke: Caused by a blood clot or other debris that travels from another part of the body (typically the heart) to the brain and blocks a blood vessel
• Risk factors include Hypertension, high cholesterol, heart disease, diabetes, obesity, smoking, and a family history of stroke.
• Atrial fibrillation, a type of irregular heartbeat, is a significant risk factor for embolic stroke

Pathophysiology

• Ischemia leads to an energy crisis in brain cells, disrupting ion homeostasis and causing cytotoxic edema
• Excitotoxicity occurs due to excessive release of glutamate, leading to neuronal damage
• Inflammation and oxidative stress contribute to further brain injury

Diagnosis

• Rapid recognition of stroke symptoms is crucial
• Common symptoms: Sudden numbness or weakness of the face, arm, or leg (especially on one side of the body), trouble speaking or understanding speech, vision problems, dizziness, loss of balance or coordination, and severe headache with no known cause
• Neurological examination assesses motor skills, sensory function, coordination, and reflexes
• Computed tomography (CT) scan of the brain is typically the first imaging test to rule out hemorrhage
• Magnetic resonance imaging (MRI) provides more detailed information about the extent and location of ischemic damage
• CT angiography (CTA) or magnetic resonance angiography (MRA) can visualize blood vessels and identify blockages
• Electrocardiogram (ECG) helps detect atrial fibrillation or other heart abnormalities.
• Blood tests assess clotting factors, blood sugar levels, and cholesterol levels

Treatment

• The primary goal of treatment is to restore blood flow to the affected area of the brain as quickly as possible
• Intravenous thrombolysis with recombinant tissue plasminogen activator (tPA) is the standard treatment for eligible patients within a specific time window (typically up to 4.5 hours from symptom onset)
• Endovascular thrombectomy: A mechanical procedure to remove the blood clot from a large blood vessel in the brain, typically performed within 6-24 hours of symptom onset
• Antiplatelet agents (e.g., aspirin, clopidogrel) are used to prevent further clot formation
• Anticoagulants (e.g., heparin, warfarin) are used in specific cases, such as stroke due to atrial fibrillation
• Supportive care: Includes managing blood pressure, controlling blood sugar, preventing complications (e.g., pneumonia, pressure ulcers), and providing nutrition
• Rehabilitation: Physical therapy, occupational therapy, and speech therapy help patients regain lost functions

Prevention

• Control risk factors: Manage hypertension, high cholesterol, diabetes, and obesity through lifestyle changes and medication
• Lifestyle modifications: Healthy diet, regular exercise, smoking cessation, and moderate alcohol consumption
• Antiplatelet therapy: Low-dose aspirin or other antiplatelet agents may be prescribed for individuals at high risk of stroke
• Anticoagulation: Warfarin or direct oral anticoagulants (DOACs) are used to prevent stroke in patients with atrial fibrillation
• Carotid endarterectomy or carotid artery stenting: Surgical procedures to remove plaque from the carotid arteries in patients with significant carotid artery stenosis

Complications

• Neurological deficits: Weakness or paralysis, speech problems, vision loss, cognitive impairment, and seizures
• Medical complications: Pneumonia, urinary tract infections, deep vein thrombosis (DVT), pulmonary embolism (PE), and pressure ulcers
• Psychological complications: Depression, anxiety, and emotional lability
• Recurrent stroke: Individuals who have had a stroke are at higher risk of having another stroke

Prognosis

• Varies depending on the severity and location of the stroke, the patient's age and overall health, and the timeliness of treatment
• Some patients recover completely or with minimal deficits, while others experience significant long-term disability
• Early rehabilitation and ongoing support can improve outcomes

Types of Ischemic Stroke

• Lacunar Stroke: Small, deep infarcts, often associated with hypertension and diabetes.
• Transient Ischemic Attack (TIA): A "mini-stroke" with temporary symptoms, serving as a warning sign for a future stroke.

Imaging Modalities in Detail

• Computed Tomography (CT): Quick, readily available, and useful for ruling out hemorrhagic stroke.
• Magnetic Resonance Imaging (MRI): More sensitive than CT for detecting early ischemic changes and small infarcts.
• Diffusion-Weighted Imaging (DWI): Detects acute ischemia within minutes of symptom onset.
• Perfusion Imaging: Assesses blood flow to the brain and helps identify salvageable tissue (penumbra).

Thrombolysis

• Recombinant Tissue Plasminogen Activator (rtPA): A thrombolytic drug that dissolves blood clots and restores blood flow.
• Time Window: Ideally administered within 3 hours of symptom onset, but may be given up to 4.5 hours in select patients.
• Contraindications: Include recent surgery, bleeding disorders, and uncontrolled hypertension.

Mechanical Thrombectomy

• A catheter-based procedure to remove large blood clots from major brain arteries.
• Performed in specialized stroke centers, typically within 6-24 hours of symptom onset, for patients with large vessel occlusions.

Medical Management

• Blood Pressure Control: Maintaining optimal blood pressure to prevent further brain injury.
• Glucose Control: Managing blood sugar levels in diabetic patients to avoid exacerbating ischemic damage.
• Temperature Control: Preventing fever, which can increase metabolic demand and worsen outcomes.
• Prevention of Secondary Complications: Addressing issues such as aspiration pneumonia, DVT, and pressure ulcers.

Rehabilitation

• Physical Therapy: Focuses on improving motor skills, balance, and coordination.
• Occupational Therapy: Helps patients regain skills needed for daily living activities.
• Speech Therapy: Addresses communication and swallowing difficulties.
• Psychological Support: Counseling and support groups to manage emotional and cognitive challenges.