Superficial Temporal Artery–Middle Cerebral Artery Bypass

Indications

• Atherosclerotic carotid artery occlusion with hemodynamic insufficiency in patients that have suffered symptomatic ischemia despite best medical therapy.

  • In nonselected patient populations, a multicenter randomized controlled trial showed no benefit of superficial temporal artery–middle cerebral artery (STA–MCA) bypass for patients with symptomatic carotid occlusive disease.

  • The Carotid Occlusion Surgery Study was designed to examine the effect of STA–MCA bypass (vs. best medical therapy) on the incidence of recurrent ischemic stroke in patients with symptomatic carotid occlusion and “misery perfusion” on positron emission tomography (PET). No benefit was identified in patients treated with surgery versus those treated with medical therapy alone. Given the above studies, it is necessary for patients to fail medical therapy prior to being considered for revascularization.

• Moyamoya disease with ischemic symptoms.

  • Although not validated by a large randomized controlled trial, it is generally accepted that surgical revascularization for patients with moyamoya disease with ischemic symptoms is beneficial. This conclusion is based on multiple case series indicating that STA–MCA bypass provides long-term reduction in ischemic symptoms in adult patients with moyamoya disease. Additionally, recent literature from the Japanese Adult Moyamoya Trial shows a trend in the reduction of hemorrhagic complications after STA–MCA bypass.

• Complex intracranial aneurysms and skull base tumors.

  • Surgical revascularization is frequently performed during complex intracranial procedures to prevent ischemic complications after planned sacrifice of a major intracerebral artery. STA–MCA bypass is often the procedure of choice when the amount of flow augmentation required is modest (e.g., sacrifice of an M2 branch of the MCA, occlusion of the internal carotid artery in a patient with mild hemodynamic compromise by temporary balloon occlusion testing).