[Indications for Extracranial-Intracranial Bypass Surgery]

Area of Science:

• Neurosurgery
• Neurology
• Vascular Surgery

Background:

• Randomized trials have not established the efficacy of extracranial-intracranial (EC-IC) bypass for secondary ischemic stroke prevention.
• Current guidelines do not recommend EC-IC bypass for patients with transient ischemic attack or ischemic stroke near middle cerebral or carotid artery stenosis/occlusion.

Purpose of the Study:

• To review the current recommendations and indications for EC-IC bypass surgery.
• To highlight specific patient populations where EC-IC bypass may be beneficial despite general contraindications.

Main Methods:

• Review of existing clinical guidelines (AHA/ASA, Japan Stroke Society).
• Analysis of evidence regarding EC-IC bypass in Moyamoya disease and complex aneurysms.
• Examination of perioperative management and adjunctive therapies for hyperperfusion.

Main Results:

• EC-IC bypass is generally not recommended (Class III, Level A) for secondary stroke prevention in most cases.
• Japan Stroke Guideline 2021 recommends EC-IC bypass for patients with severe hemodynamic impairment (misery perfusion) if cerebral blood flow is <80% and vascular reserve is <10%.
• EC-IC bypass is established for Moyamoya disease and indicated for specific complex aneurysms and dissections.

Conclusions:

• EC-IC bypass efficacy remains controversial for general secondary stroke prevention.
• Careful patient selection is crucial, particularly for those with severe hemodynamic compromise.
• Perioperative management and adjunctive treatments are vital for optimizing outcomes and preventing complications like hyperperfusion.