Acute Ischemic Stroke 

1️⃣ Definition

Acute ischemic stroke (AIS) is a sudden focal neurological deficit due to arterial occlusion, resulting in cerebral infarction.

It accounts for ~85% of all strokes, the remainder being hemorrhagic.

Pathologically:

• Thrombotic occlusion
• Embolic occlusion
• Systemic hypoperfusion
• Small vessel lipohyalinosis

Pathophysiology 

Core vs Penumbra Concept

When cerebral blood flow (CBF) falls:

Two Zones

1. Infarct Core

• Severely ischemic
• Irreversible necrosis

2. Ischemic Penumbra

• Functionally silent but structurally viable
• Salvageable with reperfusion

Etiology & Classification

1️⃣ TOAST Classification

Common Causes in ICU Practice

• Atrial fibrillation
• Post-MI LV thrombus
• Carotid stenosis
• Sepsis-associated embolism
• Hypercoagulable states
• Malignancy (Trousseau)

 Vascular Territories (Clinically Tested)

1️⃣ Middle cerebral artery (MCA)

• Contralateral hemiparesis (face + arm > leg)
• Aphasia (dominant hemisphere)
• Hemineglect (non-dominant)
• Homonymous hemianopia

 Most common stroke.

2️⃣ Anterior cerebral artery (ACA)

• Leg weakness > arm
• Abulia
• Urinary incontinence

3️⃣ Posterior cerebral artery (PCA)

• Homonymous hemianopia
• Visual agnosia
• Thalamic pain syndrome

4️⃣ Basilar artery

• Locked-in syndrome
• Quadriplegia
• Coma

NIHSS (National Institutes of Health Stroke Scale)

• 0–42 scale
• 25 → severe stroke

According to 2021 AHA/ASA:

• NIHSS ≥6 supports thrombectomy eligibility (if LVO present)
• Very low NIHSS + LVO → controversial but may still treat if disabling

• Investigations in a Patient with Suspected Stroke

These must be done immediately on arrival.

Non-contrast CT Brain

Purpose:

• Exclude hemorrhage
• Identify early ischemic signs

Early CT Signs

• Loss of insular ribbon
• Lentiform nucleus obscuration
• Hyperdense MCA sign

ASPECTS (Alberta Stroke Program Early CT Score)

• ASPECTS = a 10-point quantitative score used on non-contrast CT (NCCT) to assess early ischemic changes in anterior circulation (MCA territory) stroke.

AHA/ASA 2021 Guideline Position:

• ASPECTS ≥6 → reasonable for IV thrombolysis
• Very low ASPECTS (≤5) → increased hemorrhage risk but not absolute contraindication (clinical judgment required)

Important:
IV thrombolysis decision is primarily time-based (<4.5 hr), but ASPECTS helps risk stratify.

Vascular Imaging (If Candidate for Reperfusion)

CT Perfusion / DWI–FLAIR Mismatch

Used to:

• Identify core vs penumbra
• Select patients for thrombectomy up to 24 hours

 Laboratory Investigations

These should NOT delay thrombolysis unless abnormality suspected.

 Cardiac Evaluation-Stroke is often cardioembolic.

Etiology-Specific Investigations (Selective)

Indicated in young stroke or unexplained cases.

Reperfusion Therapy 

1️⃣ IV Thrombolysis

Drug: Alteplase (tPA)

Time Window:

• Within 4.5 hours

Inclusion:

• Measurable deficit
• CT excludes bleed

Contraindications 

Tenecteplase vs Alteplase in Acute Ischemic Stroke

Primary references:

• 2021 AHA/ASA Acute Ischemic Stroke Guideline
• 2023 European Stroke Organisation (ESO) thrombolysis update
• Key RCTs: EXTEND-IA TNK trial, AcT trial

2️⃣ Mechanical Thrombectomy

Indications:

• Large vessel occlusion
• Within 6 hours (up to 24 hrs in selected patients based on perfusion imaging)

Best outcomes in:

• ICA
• Proximal MCA

Mechanical thrombectomy is recommended up to 24 hours from last known well in patients with anterior circulation large vessel occlusion who demonstrate a favorable perfusion mismatch (DAWN/DEFUSE 3 criteria).

Blood Pressure Management

Before Thrombolysis

• Keep <185/110 mmHg

After Thrombolysis

• Maintain <180/105 for 24 hrs

If NOT thrombolysed:

• Treat only if >220/120

Preferred drugs:

• Labetalol
• Nicardipine infusion

 Fluids & Hemodynamics

• Avoid hypotension
• Use isotonic saline
• Avoid glucose-containing fluids

 Glycemic Control

• Maintain 140–180 mg/dL
• Avoid hypoglycemia (can mimic stroke)

Ventilation in ICU

Indications for intubation:

• GCS <8
• Loss of airway reflex
• Posterior circulation stroke
• Aspiration risk

Avoid:

• Hyperventilation (unless impending herniation)

Cerebral Edema & Malignant MCA

Occurs 24–72 hours.

Signs:

• Declining GCS
• Pupillary changes
• Midline shift

Management:

• Head elevation
• Hypertonic saline
• Mannitol
• Decompressive hemicraniectomy (life-saving in young patients)

 Complications in ICU

 Antiplatelet Therapy

If NOT thrombolysed:

• Aspirin 300 mg stat → then 75–150 mg daily

If thrombolysed:

• Start after 24 hrs (repeat CT first)

 Anticoagulation (Cardioembolic Stroke)

For AF:

• Start DOAC after:
• 1 day (TIA)
• 3 days (small stroke)
• 6 days (moderate)
• 12–14 days (large)

 Secondary Prevention

1. Statins (high intensity)
2. BP control (<130/80 long term)
3. Diabetes control
4. Carotid endarterectomy if >70% stenosis
5. Smoking cessation

Why Not Dual Antiplatelet Lifelong?

Because trials like:

• CHANCE trial
• POINT trial

Showed:

• Benefit in first 21 days
• Bleeding risk increases beyond that

Hence:
👉 DAPT short term only

Role of CHA₂DS₂-VASc Score in Acute Ischemic Stroke

CHA₂DS₂-VASc Components

Maximum = 9 points

If a patient has AF and suffers an ischemic stroke:

👉 They automatically score 2 points (for prior stroke/TIA)
👉 Therefore, anticoagulation is strongly indicated lifelong

So in secondary prevention after AF-related stroke:

CHA₂DS₂-VASc becomes almost redundant —
because prior stroke already mandates anticoagulation.

Where Exactly Does It Help?

1️⃣ Primary Prevention (Most Important Use)

In a patient with AF but NO prior stroke:

(OAC = Oral anticoagulation, DOAC preferred)

2️⃣ Secondary Prevention After Stroke

If AF is confirmed:

👉 Anticoagulation indicated regardless of total score
(because stroke gives 2 points)