Summary: Cerebral revascularization is indicated for symptomatic chronic common carotid artery (CCA) occlusion. Although a variety of bypass surgeries have been reported, some of them are high-flow bypasses that carry the risk of hyperperfusion. In this article, we report two different low-flow bypass surgeries with radial artery graft, depending on the hemodynamics of CCA occlusion.Case 1 was an 82-year-old male who suffered right hemodynamic ischemic stroke with a large area of misery perfusion. Because of right distal internal carotid artery (ICA) occlusion, a left superficial temporal artery-right middle cerebral artery bypass was performed using radial artery (RA) interposition graft. This patient had a good outcome.Case 2 was a 74-year-old male who presented with intractable recurrent right cerebral ischemic stroke. Because the distal internal carotid artery was patent through collateral flow from the vertebral artery, ipsilateral thyrocervial trunk-RA interposition graft-ICA bypass was performed.Even though the bypass was successful, the patient's outcome was poor due to postoperative cardiac embolism.Bypasses using distal vessels of smaller caliber as donor pedicles, such as contralateral superficial temporal artery and thyrocervical trunk, can reduce hyperperfusion risk and make the procedure easier. Bypass patient selection and careful perioperative management are critical to obtain good clinical outcomes from these procedures.
The anatomy of perforating arteries is quite important in microneurosurgery, because any blood flow insufficiency in the perforating arteries can cause serious neurological deficits. Especially in aneurysm clipping, surgeons must be aware of the anatomical variation of the perforators related to the aneurysm. For example, the anterior choroidal artery sometimes arises from the aneurysm itself or it may also arise as 2 4 independent vessels. Lenticulostriate arteries usually arise from the posterior aspect of the M1 segment, but also from the M1 M2 bifurcation or the M2 segment. Hypothalamic arteries originate from the posterior aspect of the anterior communicating artery and are ordinarily difficult to confirm by the pterional approach. To preserve perforator blood flows, surgeons must first identify all of the perforators around an aneurysm. Neuroendoscopy helps us in this task by allowing us to observe the blind area of the microscope. Also, clips must be placed in such a way as to spare the blood flow of the perforators. After clipping, the patency of the perforators is confirmed by Doppler ultrasonography, indocyanine green ICG videoangiography and motor evoked potential MEP monitoring. As each of these intraoperative monitoring methods may yield a false negative result on its own, the combination of multiple modalities is mandatory for avoiding neurological complications due to perforator injury.
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