What is the recommended management for a patient presenting within 4.5 hours of symptom onset with an acute middle cerebral artery M2 segment occlusion and a vertebral‑artery dissection?

Management of Acute M2 Occlusion with Vertebral Artery Dissection

For a patient presenting within 4.5 hours with an acute M2 occlusion and concurrent vertebral artery dissection, proceed immediately with IV alteplase (0.9 mg/kg, max 90 mg) followed by mechanical thrombectomy of the M2 occlusion using stent retriever or direct aspiration, while initiating antithrombotic therapy for the vertebral dissection after the acute intervention is complete. 1, 2

Immediate Acute Stroke Management (Priority #1)

IV Thrombolysis

• Administer IV alteplase within 4.5 hours of symptom onset, aiming for door-to-needle time <60 minutes. 2 The presence of vertebral artery dissection does NOT contraindicate IV thrombolysis unless there is evidence of intracranial extension with subarachnoid hemorrhage risk. 1

• Maintain blood pressure ≤180/105 mmHg during and for 24 hours after thrombolytic therapy using rapidly titratable agents such as labetalol (10-20 mg IV over 1-2 minutes) or nicardipine (5 mg/h IV, titrate by 2.5 mg/h every 5-15 minutes to maximum 15 mg/h). 1, 2

Mechanical Thrombectomy for M2 Occlusion

• Proceed with mechanical thrombectomy (groin puncture) within 6 hours of symptom onset for the M2 occlusion, as benefits are uncertain but reasonable in carefully selected patients. 1 The 2018 AHA/ASA guidelines note that while pooled data from HERMES trials showed favorable direction of treatment effect for M2 occlusions (adjusted common OR 1.28; 95% CI 0.51-3.21), the benefit was not statistically significant. 1

• Direct aspiration as first-line technique is preferred for M2 occlusions, as it achieves higher first-pass effect rates (56.25%) compared to stent retrievers. 3 Meta-analysis data shows M2 thrombectomy achieves 59% functional independence (mRS 0-2) and 81% recanalization rates (TICI 2b/3). 4

• Target TICI 2b/3 angiographic result, as successful M2 recanalization is associated with 4.22-fold greater odds of favorable outcome compared to poor recanalization. 4

• Do NOT delay mechanical thrombectomy to assess clinical response to IV alteplase—this approach worsens outcomes (Class III recommendation). 2

Management of Vertebral Artery Dissection (Priority #2)

Timing of Antithrombotic Therapy

• Delay initiation of antithrombotic therapy for the vertebral dissection until AFTER completion of mechanical thrombectomy and confirmation of no hemorrhagic transformation on post-procedure imaging. 1 This approach balances the need for acute stroke reperfusion with the risk of hemorrhagic complications from early anticoagulation.

Antithrombotic Options (Initiate 24 hours post-thrombolysis)

• Choose between anticoagulation (heparin followed by warfarin, target INR 2.0-3.0) OR antiplatelet therapy (aspirin 81-325 mg daily or clopidogrel 75 mg daily) for 3-6 months. 1, 5

• The 2011 ACC/AHA guidelines note that observational data showed 8.3% annual rate of recurrent stroke/TIA/death with anticoagulation versus 12.4% with aspirin, though no randomized trials have established superiority of either approach. 1

• Anticoagulation may adversely influence outcomes if intracranial extension of the dissection occurs with subarachnoid hemorrhage. 1 Obtain baseline and 24-hour head CT to exclude hemorrhagic transformation before initiating anticoagulation.

Diagnostic Confirmation

• CT angiography of head and neck with IV contrast should already be completed as part of acute stroke workup, providing 100% sensitivity for vertebral dissection diagnosis. 6 Look for intimal flap, differential flow in true and false lumens, or aneurysmal degeneration. 1

Technical Considerations for Combined Pathology

Approach to Mechanical Thrombectomy

• Access the M2 occlusion via the unaffected vertebral artery or carotid circulation—avoid instrumenting through the dissected vertebral artery. 7 A case report demonstrated successful BA thrombectomy through the contralateral clean vertebral artery when ipsilateral VA was dissected. 7

• Use triaxial technique with large-bore distal access catheter plus stent retriever or direct aspiration to maximize first-pass effect and minimize distal emboli. 1

Hemorrhagic Risk Monitoring

• M2 thrombectomy carries 10% symptomatic intracranial hemorrhage risk (95% CI 6-16%). 4 This risk is compounded by subsequent need for antithrombotic therapy for vertebral dissection.

• Perform neurological examinations every 15 minutes for 2 hours, then every 30 minutes for 6 hours, then hourly for 16 hours. 1, 2 Any sudden worsening, severe headache, acute hypertension, nausea, or vomiting mandates immediate head CT. 2

Post-Procedure Management

Blood Pressure Control

• Maintain BP ≤180/105 mmHg for 24 hours post-thrombectomy to reduce hemorrhagic transformation risk. 2

• After 24 hours, blood pressure control remains important for vertebral dissection management to reduce arterial wall stress, though specific targets are not well established (Class IIb recommendation). 5

Adjunctive Therapies for Vertebral Dissection

• Initiate high-intensity statin therapy (atorvastatin 80 mg or rosuvastatin 20-40 mg daily) targeting LDL <70 mg/dL (Class IIa recommendation). 5 Statins provide pleiotropic benefits including endothelial stabilization, increased nitric oxide bioavailability, and reduced vascular inflammation beyond cholesterol reduction. 5

• Smoking cessation is mandatory (Class I recommendation). 5

Follow-up Imaging

• Repeat head CT at 24 hours or immediately if clinical deterioration occurs. 2

• Serial non-invasive imaging (CTA or MRA) of extracranial vertebral arteries at 3-6 months is reasonable to assess progression and exclude new lesions (Class IIa recommendation). 5

Common Pitfalls and Caveats

Critical Errors to Avoid

• Do NOT withhold IV thrombolysis solely because of vertebral dissection—the dissection itself is not a contraindication unless intracranial extension with SAH is present. 1

• Do NOT delay mechanical thrombectomy to "see if tPA works"—this significantly worsens outcomes. 2

• Do NOT start anticoagulation for vertebral dissection before confirming absence of hemorrhagic transformation on 24-hour imaging. 1

Surgical Rescue Options

• Surgical or endovascular revascularization of the vertebral dissection is reserved exclusively for patients with persistent or recurrent ischemic symptoms despite optimal antithrombotic therapy. 1, 5

• If malignant cerebral edema develops from M2 territory infarction, prepare for decompressive hemicraniectomy within 48 hours, which reduces mortality by approximately 50% in younger patients. 2

Prognosis

• With appropriate treatment, vertebral dissection prognosis is usually favorable. 1, 5 However, 50-95% of vertebral dissection patients develop cerebral or retinal ischemia after warning symptoms, emphasizing the importance of aggressive acute stroke management. 1, 6

• M2 thrombectomy achieves 59% functional independence at 90 days with 16% mortality. 4 First-pass effect is associated with significantly lower discharge NIHSS (median 2 vs. 5) and higher 3-month functional independence (83.33% vs. 60.34%). 3