What is the initial management for an acute infarct in the Middle Cerebral Artery (MCA) territory?

Acute MCA Territory Infarct Management

For acute MCA territory infarction, immediately perform non-contrast CT to exclude hemorrhage, administer IV alteplase (0.9 mg/kg) within 4.5 hours if eligible, and pursue mechanical thrombectomy for large vessel occlusion within 6 hours of symptom onset. 1, 2

Immediate Diagnostic Evaluation

• Perform non-contrast CT scan immediately to exclude hemorrhagic stroke and assess early ischemic changes using the ASPECTS score (Alberta Stroke Program Early CT Score) 3, 1
• Obtain CT angiography to confirm MCA occlusion location (M1, M2 segments) and evaluate collateral circulation status 1, 4
• Use diffusion-weighted MRI when available as it has 88-100% sensitivity and 95-100% specificity for detecting acute infarction, far superior to CT 3
• Calculate NIHSS score to quantify stroke severity and guide treatment decisions—median baseline scores in MCA strokes are typically 16-17 3, 2

Critical Imaging Findings That Alter Management

• Early hypodensity involving >1/3 of MCA territory on initial CT indicates increased hemorrhagic risk (8-fold increase with thrombolysis) and predicts malignant edema 3
• Hyperdense MCA sign on CT indicates thrombus in the vessel and is present in 54% of proximal MCA occlusions 3
• ASPECTS ≤6 indicates large ischemic core with higher risk of hemorrhagic transformation but may still benefit from thrombectomy 4, 2

Acute Reperfusion Therapy

Intravenous Thrombolysis

• Administer IV alteplase 0.9 mg/kg (maximum 90 mg) with 10% as bolus and remainder over 60 minutes if patient presents within 4.5 hours of symptom onset 3, 1, 2
• Do not delay IV alteplase while arranging endovascular therapy—patients eligible for IV rtPA should receive it even if mechanical thrombectomy is planned 1, 2
• Exclude patients with >1/3 MCA territory involvement on initial CT from the 3-4.5 hour window due to increased hemorrhagic risk 3

Mechanical Thrombectomy

• Perform endovascular thrombectomy for proximal MCA occlusion (M1 or proximal M2 segments) with treatment initiation (groin puncture) within 6 hours of symptom onset 1, 2
• Use stent retrievers as first-line mechanical device (Class I, Level A evidence), with combined aspiration techniques to achieve faster reperfusion 2
• Target TICI 2b/3 angiographic result (substantial or complete reperfusion) to maximize probability of good functional outcome 2
• MCA occlusions achieve 88% recanalization rates with IV thrombolysis compared to only 31% for ICA occlusions, making isolated MCA occlusions more amenable to treatment 5

Intra-arterial Thrombolysis (Alternative)

• Consider intra-arterial thrombolysis for MCA occlusion within 6 hours in patients ineligible for IV rtPA due to recent surgery or other contraindications (Class I, Level B) 3
• This requires immediate access to cerebral angiography and qualified interventionalists at an experienced stroke center 3

Blood Pressure Management

• Maintain BP ≤180/105 mmHg during and for 24 hours after mechanical thrombectomy or thrombolysis 1, 2
• Avoid antihypertensive agents that cause cerebral vasodilation as these may worsen edema 3, 1
• Monitor BP at least every 6 hours in the acute phase 1

Antiplatelet Therapy

• Administer aspirin 160-325 mg within 24-48 hours of stroke onset 1, 4, 2
• Delay aspirin for 24 hours if patient received IV thrombolysis to reduce hemorrhagic risk 2
• Use clopidogrel 75 mg daily if true aspirin allergy exists 1

Management of Cerebral Edema

Medical Management

• Elevate head of bed to 20-30 degrees to facilitate venous drainage 3, 1, 4
• Restrict free water and avoid hypotonic fluids to prevent worsening of cytotoxic edema 3, 1, 4
• Correct hypoxemia, hypercarbia, and hyperthermia as these exacerbate brain swelling 3, 1
• Administer mannitol 0.25-0.5 g/kg IV over 20 minutes every 6 hours (maximum 2 g/kg) for clinical deterioration from edema, targeting serum osmolarity 315-320 mOsm/L 1, 4

Predictors of Malignant Edema

• Brain swelling occurs in 10-20% of anterior circulation strokes, typically 2-4 days after MCA stem occlusion 3
• High-risk features include: >50% MCA territory hypodensity on CT within 12 hours, hyperdense MCA sign, involvement of additional vascular territories, history of hypertension/heart failure, and elevated white blood cell count 3
• Women and patients with additional territorial infarctions are at higher risk for progressive swelling 3

Surgical Decompression

• Perform decompressive hemicraniectomy for malignant MCA infarction to reduce mortality by approximately 50% in patients ≤60 years old 1, 4
• Optimal timing is within 48 hours of stroke onset, before severe neurological deterioration and herniation signs develop 1, 4
• Surgical technique must include: bone flap ≥12 cm diameter, extension to temporal skull base, and wide dural opening with duraplasty 1, 4
• For patients >60 years old, discuss likelihood of survival with severe disability with family, as evidence for benefit is less robust 1, 4

Indications for Early Neurosurgical Transfer

• Transfer immediately to neurosurgical center if CT shows >50% MCA territory involvement, midline shift, or compression of frontal horn/septum pellucidum 3, 4
• Clinical signs warranting transfer: progressive deterioration, bilateral ptosis, nausea/vomiting, or need for mechanical ventilation 3

Critical Pitfalls to Avoid

• Do not wait to assess clinical response to IV rtPA before pursuing endovascular therapy—this delays definitive treatment and worsens outcomes (Class III recommendation) 2
• Do not use corticosteroids, furosemide, or hyperventilation for cerebral edema management—no evidence supports efficacy in stroke-related edema 3
• Do not aggressively lower blood pressure in acute phase, particularly with vasodilating agents, as this may worsen ischemia 3, 1
• Recognize that rtPA may accelerate cerebral edema onset—symptomatic infarct swelling occurs earlier (mean 27.6 vs 45.4 hours) in thrombolyzed patients with large MCA infarcts 6
• Every 30-minute delay in recanalization decreases chance of good outcome by 8-14%—time is brain 2