Summary Several operative generalities are applicable to STA-MCA revascularization procedures.
The location of both branches of the STA is determined via Doppler ultrasonography and outlined with a marking pen. Based on the preoperative angiogram, the surgeon decides whether the anterior (frontal) or posterior (parietal) branch is more suitable for anastomosis. Local anesthetic is not used to avoid needle-induced injury or spasm of the STA. Most commonly, the posterior branch of the STA is selected because of its proximity to the posterior aspect of the sylvian fissure (located approximately 6 cm above the external acoustic meatus) where M4 vessels sufficient for bypass are commonly located. The anterior branch of the STA is selected when the posterior branch is of insufficient size or has been occluded during a prior craniotomy. When the posterior branch is used, a linear skin incision is made directly over the artery from above the superior temporal line to the zygoma ( A ; solid line depicts skin incision site). When the anterior branch is used, two options for the skin incision exist: a linear incision directly over the artery ( A ), or a curvilinear incision behind the hairline with separate dissection of the underlying STA from the skin flap ( B ). We prefer the latter because it provides better bony exposure to the posterior aspect of the sylvian fissure and avoids a skin incision that often extends anterior to the patient’s hairline.
Indications - Atherosclerotic carotid artery occlusion with hemodynamic insufficiency - Moyamoya disease with ischemic symptoms. - Complex intracranial aneurysms and skull base tumors.
Contraindications - Atherosclerotic carotid artery occlusion without hemodynamic insufficiency - Atherosclerotic intracranial artery stenosis. - Cerebral vasospasm. - Planned sacrifice of a major intracerebral artery in patients with marked hemodynamic compromise by temporary balloon occlusion testing.
Complications - Anastomosis leak - Parenchymal hemorrhage - Cerebral edema - Disautoregulation - Scalp ischemia - Myocardial infarction - Pneumonia - Deep venous thrombosis - Pulmonary embolism - Stenosis at the anastomosis site - Compression of the donor vessel - Bleeding at the anastomotic site.