What is the evidence for thrombolysis with tissue plasminogen activator (tPA) in basilar occlusion?

Evidence for Thrombolysis in Basilar Artery Occlusion

Intra-arterial thrombolysis is a reasonable treatment option for patients with basilar artery occlusion, particularly those with severe clinical deficits, though mechanical thrombectomy is now preferred when available. 1

Current Treatment Approach for Basilar Occlusion

First-Line Treatment: Mechanical Thrombectomy

• Endovascular thrombectomy is now the preferred treatment for basilar artery occlusion, especially in patients with:
  • Severe neurological deficits (NIH Stroke Scale ≥6)
  • Presentation within 24 hours of symptom onset 1
  • Retrievable stents are recommended as first-choice devices 1

Role of Thrombolysis

1. Intravenous tPA:

   • Should be administered to eligible patients even if endovascular thrombectomy is planned 1
   • Standard time window is within 4.5 hours of symptom onset 1
   • After tPA administration, ASA (aspirin) should be delayed until after the 24-hour post-thrombolysis scan has excluded intracranial hemorrhage 1

2. Intra-arterial thrombolysis:

   • May be considered for patients who:
     • Present within 6 hours of symptom onset 1
     • Are not eligible for IV tPA 1
     • Have contraindications to IV tPA (such as recent surgery) 1
   • Case series data suggest benefit in basilar artery occlusion even at longer time intervals 1

Evidence for Thrombolysis in Basilar Occlusion

Observational Studies

• A large multicenter observational cohort study showed that intra-arterial thrombolysis was associated with:

  • Better results than antithrombotic therapy among patients with severe clinical deficits
  • Poorer outcomes than antithrombotic therapy in patients with mild to moderate baseline deficits 1

• Recanalization rates with IV tPA alone for basilar artery occlusion are approximately 30% 1

• Combined approaches using IV abciximab and intra-arterial tPA have shown:

  • High recanalization rates (85%) in basilar occlusion
  • However, functional outcomes remained poor (15% favorable outcome), likely due to late treatment initiation 2

Prognostic Factors

• Variables affecting outcomes in basilar occlusion thrombolysis include:
  • Recanalization status (mortality 46% with recanalization vs. 92% without) 3
  • Length of basilar artery obstruction 3
  • Patient age 3
  • Collateral circulation 3
  • Etiology (embolic occlusions respond better to thrombolysis than atherothrombotic) 3
  • Pretreatment Glasgow Coma Scale score (higher scores associated with better outcomes) 4

Practical Considerations

Treatment Algorithm

1. Confirm basilar occlusion with CT/MR angiography
2. If within 4.5 hours of symptom onset and no contraindications, administer IV tPA
3. Prepare for endovascular thrombectomy regardless of IV tPA eligibility
4. For patients ineligible for both IV tPA and thrombectomy, consider intra-arterial thrombolysis if:
   • Within 6 hours of symptom onset
   • At an experienced stroke center with immediate access to cerebral angiography and qualified interventionalists

Safety Considerations

• Symptomatic intracranial hemorrhage occurs in approximately 10% of patients treated with intra-arterial thrombolysis 1
• The availability of intra-arterial thrombolysis should not preclude the administration of IV tPA in eligible patients 1

Emerging Approaches

• Combined approaches using glycoprotein IIb/IIIa inhibitors (like abciximab) with intra-arterial thrombolysis show promising results for basilar occlusion 5
• Mechanical thrombectomy following IV-rtPA administration has shown successful reperfusion in all patients in one small study, with good outcomes (mRS 0-2) in 45% of patients 4

Pitfalls to Avoid

• Delaying treatment initiation significantly worsens outcomes in basilar occlusion
• Failing to consider mechanical thrombectomy as the first-line treatment when available
• Withholding IV tPA in eligible patients when endovascular treatment is planned
• Not recognizing that basilar occlusion patients may benefit from treatment at longer time windows than anterior circulation strokes