Microsurgical anatomy of perforators: The efficacy of ICG videoangiography and neuroendoscopy

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.