Indications for surgical intervention in middle cerebral artery obstruction

The clinical, angiographic, and surgical characteristics of 31 patients with high-grade middle cerebral artery (MCA) stenosis or occlusion (jointly termed "MCA obstructions") referred for cerebral revascularization by extracranial-intracranial (EC-IC) bypass are reviewed. Overall, 12 (66%) of the 18 patients with stenosis and all 13 (100%) of those with complete occlusion experienced clinically evident infarctions. Twenty-five of these patients underwent arteriography at least twice during their clinical course. Eleven (44%) demonstrated significant improvement in flow or complete resolution of obstruction on their second study. Ten of these 11 were patients in whom the initial arteriography was done within 2 weeks of symptom onset. Five other patients with stenosis exhibited obstruction that was worse on serial arteriography without surgical intervention. The high incidence of resolution of MCA obstructions indicates that surgery should not be contemplated in most instances until delayed arteriography has been performed, at least 6 weeks after the onset of symptoms. Proximal embolic sources, such as the cervical carotid bifurcation, should receive carotid endarterectomy and repeat arteriography in appropriate patients prior to consideration of EC-IC bypass. Persistent high-grade MCA obstructions are thereafter potential candidates for EC-IC bypass, since leptomeningeal collateral vessels are marginal in their protective ability. Overall, of 15 patients who underwent an EC-IC bypass procedure, 14 were either stable or improved postoperatively, and 13 have been free of any further ischemic events without the use of major anticoagulant agents.