Overview

This lecture summarizes the current evidence-based approach for diagnosing and managing acute ischemic stroke, focusing on time-sensitive treatments, imaging, and institutional protocols.

Initial Assessment & Diagnosis

• Assess time from stroke symptom onset to ED arrival; timing is critical ("time is brain").
• Determine last known well time, including whether it's a wake-up stroke.
• Evaluate severity of neurological deficits with the NIH Stroke Scale (NIHSS).
• Obtain a blood glucose to rule out stroke mimics like hypoglycemia.
• Order non-contrast CT head immediately to rule out hemorrhage; follow with advanced imaging (CT/CTA/MRI) as indicated.

Treatment Strategies

• IV alteplase (tPA) is first-line if less than 4.5 hours from symptom onset and NIHSS ≥ 6, no high bleeding risk, or irreversible brain injury.
• tPA dose: 0.9 mg/kg (max 90 mg), with 10% as bolus, rest over 60 minutes.
• Start tPA as soon as negative head CT confirms no bleed; do not wait for labs except for glucose.
• Strictly control BP to <185/110 mmHg before tPA, and <180/105 mmHg for 24h after.
• Mechanical thrombectomy indicated for large vessel occlusions (LVO), NIHSS ≥ 6, mainly within 6 hours (may be up to 24h for select patients).
• Both tPA and thrombectomy may be used together if eligible.

Extended & Alternative Therapies

• Wake-Up and extended window studies suggest tPA can benefit select patients up to 9 hours based on imaging and NIHSS < 25.
• Mechanical thrombectomy has benefit up to 16-24 hours post-onset for severe strokes with LVO, based on advanced imaging criteria.
• Tenecteplase (TNK) is an alternative to tPA; studies show similar efficacy and safety.

Supportive & Secondary Management

• Admit patients to stroke unit or neuro ICU for close monitoring and best outcomes.
• Avoid early antithrombotic therapy (aspirin, dual antiplatelet, anticoagulation) within 24 hours after tPA due to bleeding risk.
• Initiate aspirin 160–300 mg after 24h; dual antiplatelet therapy may be started if indicated.
• Routine anticoagulation not superior to aspirin except in special populations (e.g., afib).
• Provide DVT prophylaxis (compression stockings) if immobilized.
• Manage fever and maintain oxygen saturation >94%.
• Allow permissive hypertension unless giving tPA or hypertensive emergency present.

Key Terms & Definitions

• NIH Stroke Scale (NIHSS) — Objective tool for measuring stroke severity.
• Last Known Well Time — Last observed time patient was symptom-free.
• tPA (Alteplase) — Thrombolytic used for acute ischemic stroke within time window.
• Mechanical Thrombectomy — Procedure to remove clot from large brain vessel.
• Penumbra — Brain tissue at risk but not yet infarcted; salvageable with timely intervention.
• Modified Rankin Scale (mRS) — Measures degree of disability/dependence after stroke.
• Large Vessel Occlusion (LVO) — Blockage of major cerebral artery.

Action Items / Next Steps

• Review and follow your institution's specific acute stroke protocols.
• Read the summary algorithm in the referenced article for visual workflow.
• Practice NIHSS scoring and recognize tPA/mechanical thrombectomy criteria.
• Prepare to communicate time of onset, NIHSS, and imaging findings promptly in all suspected cases.

Certainly! Here's a comprehensive, detailed summary and review of the lecture on acute ischemic stroke, covering all key points and nuances:

Comprehensive Summary and Review: Acute Ischemic Stroke Management

Epidemiology and Context

• Acute ischemic stroke is a highly common and critical condition, with approximately 700,000 cases annually.
• It remains a "moving target" due to evolving research, conflicting literature, and rapidly changing treatment protocols.
• Institutional protocols vary widely; clinicians must stay updated on local guidelines while understanding the broader evidence base.

Initial Assessment and Diagnosis

Time Sensitivity

• Time from symptom onset to ED arrival is the most critical factor guiding treatment decisions.
• Always determine the Last Known Well (LKW) time:
  • Ask when the patient was last seen without symptoms.
  • Clarify if the stroke was a wake-up stroke (symptoms noticed upon waking), which complicates timing.
• "Time is brain" — every minute delay results in more irreversible brain damage.

Neurological Severity

• Use the NIH Stroke Scale (NIHSS) to objectively quantify neurological deficits.
• NIHSS score guides treatment eligibility and prognosis.
• Scores <6 generally indicate minor strokes; >6 indicate moderate to severe strokes.

Rule Out Stroke Mimics

• Check blood glucose immediately to exclude hypoglycemia, a common stroke mimic that can be rapidly reversed.
• Treat hypoglycemia promptly if detected.

Imaging

• Obtain a non-contrast CT head immediately to exclude hemorrhagic stroke.
• If CT is negative but suspicion remains high, advanced imaging is used to assess salvageable brain tissue:
  • CT Angiography (CTA) or MR Angiography (MRA) to detect large vessel occlusions (LVO).
  • CT Perfusion or Diffusion-Weighted MRI to identify ischemic penumbra (tissue at risk but not yet infarcted).
• Imaging findings guide decisions on thrombolysis and mechanical thrombectomy.

Treatment Modalities

Intravenous Thrombolysis (tPA - Alteplase)

• Standard window: Administer IV alteplase within 4.5 hours of symptom onset.
• Dose: 0.9 mg/kg (max 90 mg), with 10% as bolus over 1 minute, remainder infused over 60 minutes.
• Eligibility:
  • NIHSS ≥ 6 (not recommended for minor strokes with NIHSS < 6).
  • No evidence of intracranial hemorrhage or irreversible brain injury on imaging.
  • No excessive bleeding risk or coagulopathy.
• Administration:
  • Start immediately after negative non-contrast CT.
  • Do not delay for labs (except glucose).
  • Manage blood pressure to <185/110 mmHg before administration.
  • Maintain BP <180/105 mmHg for 24 hours post-infusion.
• Benefits:
  • Reduces disability.
  • Greatest benefit if given within 3 hours; some benefit up to 4.5 hours.
• Risks:
  • Increased risk of symptomatic intracranial hemorrhage (~6.8% vs 1.3% without tPA).
  • Must discuss risks and benefits with patients/families.

Extended Window Thrombolysis (Wake-Up Stroke and Beyond)

• Studies (e.g., WAKE-UP trial) show select patients may benefit from tPA up to 9 hours post LKW or if wake-up stroke.
• Criteria include:
  • NIHSS < 25.
  • Imaging showing salvageable penumbra.
  • No plan for thrombectomy.
• Institutional protocols vary; follow local guidelines.

Mechanical Thrombectomy

• Indicated primarily for large vessel occlusions (LVO) (e.g., internal carotid artery, proximal middle cerebral artery).
• Best outcomes if performed within 6 hours of symptom onset.
• Extended window thrombectomy (up to 16-24 hours) supported by trials like DAWN and DEFUSE 3 for select patients with favorable imaging and NIHSS ≥ 6 or 10.
• Often performed in conjunction with IV tPA if eligible.
• Procedure involves clot retrieval via catheter (stent retriever or aspiration).
• Blood pressure management during and after thrombectomy is less clearly defined but generally monitored closely.

Alternative Thrombolytic: Tenecteplase (TNK)

• TNK is a newer thrombolytic agent given as a single bolus.
• Advantages:
  • Easier and faster administration compared to alteplase infusion.
  • More fibrin-specific and resistant to plasminogen activator inhibitor.
• Studies show TNK is non-inferior to alteplase in efficacy and safety.
• Increasingly incorporated into guidelines as an alternative.

Supportive and Secondary Management

Monitoring and Admission

• Admit all acute ischemic stroke patients to a stroke unit or neuro ICU for specialized care.
• Continuous monitoring of neurological status, vital signs, and complications.
• Stroke units improve outcomes.

Blood Pressure Management

• If administering tPA, strict BP control is mandatory (<185/110 mmHg before, <180/105 mmHg after).
• If not receiving tPA, permissive hypertension is often allowed to maintain cerebral perfusion.
• Avoid aggressive BP lowering unless hypertensive emergency or other indications.
• For thrombectomy patients, BP targets are less clear; reasonable to maintain stable BP.

Antithrombotic Therapy

• Aspirin (160-300 mg) started 24 hours after tPA reduces risk of recurrent stroke and death.
• Dual antiplatelet therapy (aspirin + clopidogrel) may be considered in minor stroke or TIA to reduce recurrence risk.
• Therapeutic anticoagulation (e.g., heparin) within 48 hours is not superior to aspirin and increases bleeding risk.
• Special populations (e.g., atrial fibrillation) require tailored anticoagulation strategies, usually after acute phase.

DVT Prophylaxis

• Use pneumatic compression stockings for immobilized patients.
• Avoid early subcutaneous heparin due to bleeding risk.

Other Supportive Care

• Maintain oxygen saturation >94%.
• Treat fever aggressively; hyperthermia worsens brain injury.
• Monitor for cerebral edema and herniation; urgent neurosurgical consult if suspected.
• Cardiac monitoring is essential due to stroke-heart interactions.

Areas of Uncertainty and Emerging Concepts

Mobile Stroke Units

• Ambulances equipped with CT scanners and stroke teams aim to reduce time to diagnosis and treatment.
• High cost (~$1 million/unit) and resource-intensive.
• Efficacy and cost-effectiveness still under evaluation.

Blood Pressure Management Post-Thrombectomy

• No clear consensus on optimal BP targets.
• Most centers maintain close monitoring and avoid extremes.

Global and Ethnic Variations

• Stroke treatment practices vary worldwide.
• Genetic and ethnic differences may influence bleeding risk and treatment response.

Summary Algorithm (Conceptual)

1. Assess NIHSS and LKW time.
2. Obtain non-contrast CT head immediately.
3. If <4.5 hours and NIHSS ≥ 6, no contraindications → administer IV tPA immediately.
4. If >4.5 hours or wake-up stroke → consider advanced imaging and extended window criteria for tPA.
5. Evaluate for large vessel occlusion with CTA/MRA.
6. If LVO and NIHSS ≥ 6 → consider mechanical thrombectomy (within 6 hours or extended window if criteria met).
7. Admit to stroke unit/neuro ICU for monitoring.
8. Manage BP, glucose, oxygen, fever, and prevent complications.
9. Delay antithrombotics for 24 hours post-tPA; start aspirin thereafter.
10. Tailor anticoagulation for special populations.

Key Takeaways for Clinical Practice and Exams

• Time is critical: early recognition and treatment save brain tissue.
• NIHSS is essential for assessing stroke severity and guiding therapy.
• IV alteplase remains first-line within 4.5 hours for eligible patients.
• Mechanical thrombectomy is a powerful adjunct for LVO strokes.
• Extended windows for both therapies exist but require advanced imaging and institutional protocols.
• Tenecteplase is an emerging alternative thrombolytic.
• Supportive care and secondary prevention are vital for outcomes.
• Always follow your institution’s protocols and consult neurology/stroke specialists.

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