Middle cerebral artery aneurysm (MCAa) accounts for 15%-30% of all cerebral aneurysms/ It is a common neurosurgical aneurysm of the cerebral artery, which has a good outcome compared to cerebral aneurysms of its fife site due to the relatively shallow surgical field. However, the middle cerebral artery is responsible for a relatively large area of cerebral blood supply, and the patient’s postoperative functional prognosis is largely dependent on surgical technique. Based on retrospective analysis of surgical results, although the chance of postoperative hemorrhage exists with MCAa surgery, the major postoperative complication is often cerebral infarction. The causes of cerebral infarction are related to intraoperative mechanics, pulling the artery, prolonged temporary vascular block or improper block, delayed cerebral ischemia and venous cerebral infarction caused by vasospasm, and the location of the aneurysm clip during aneurysm clamping. At present, MCAa mostly favors surgical treatment. In order to improve the surgical effect, this paper discusses how to prevent cerebral infarction caused by vascular injury during surgery. I. Characteristics of middle cerebral artery aneurysm The incidence of multiple aneurysms is high, and aneurysms without subarachnoid hemorrhage (SAH) are almost undetectable, and if they are detected, they tend to rupture or rupture aneurysms in other parts of the brain, which are detected after angiography, and the unruptured aneurysms are often found incidentally when MRA or CTA is performed for the symptoms of other diseases. It is easy to be missed. Local hematoma is often formed after rupture of aneurysm, which is easy to be mixed and slipped with {blood pressure cerebral hemorrhage. Only hematoma removal surgery is performed, and the condition has been serious when postoperative rebleeding is detected and misdiagnosed, which affects the functional prognosis, and increases the difficulty of surgery. The incidence of large and giant aneurysms is high, and they are located in the first of all parts of the body, often with the onset of cerebral ischemia, manifested as contralateral limb activity disorders, and infarction in the basal ganglia region on cranial CT. The morphology of the aneurysm was mostly multicystic, with a wide neck and the body of the aneurysm was composed of several small vesicles. The aneurysms were mostly located in the bifurcation of Ml and M2, with many surrounding vessels and a variable number of branching arteries of different diameters and sizes. The above characteristics of MCAa determine that the aneurysm clamping operation may easily cause stenosis or occlusion of the aneurysm-carrying artery and branch arteries. Second, the choice of surgical approach Individualized choice of surgical approach is one of the most important aspects to avoid large damage and reduce complications.0 Currently, there are three types of surgical approaches: proximal approach, distalapproach and transcortical approach. The choice of which approach should be considered: (1) the location of the aneurysm, the top of the aneurysm towards the morphology size, the width and narrowness of the aneurysm neck and the three-dimensional relationship with the surrounding blood vessels. (2) The vascular course, the height of the internal carotid artery bifurcation, the distance from the internal carotid artery bifurcation to the aneurysm, the course of the Ml and the relationship between the Ml and the aneurysm. (3) Other factors, such as the presence or absence of hemorrhage, the amount of hemorrhage and the size of the hematoma. The internal carotid artery bifurcation is relatively low, and the distance from the internal carotid artery bifurcation to the aneurysm is relatively short, which is suitable for choosing the proximal approach. The proximal approach separates the internal carotid artery from the proximal to the distal end, exposing the internal carotid artery, the middle cerebral artery Ml throughout the entire length of the internal carotid artery and its junction with M2. Although the exposure range is wide, it is one of the safest and most effective routes, and it is the easiest way to control the lesion in case of rupture of the aneurysm during the operation. This approach is particularly suitable for large, giant, type aneurysms. For ruptured aneurysms accompanied by hematoma formation, the frontal or temporal cortical approach is chosen depending on the location of the hematoma. Because both the Ml and M2 junctions are below the lateral fissure, the transcortical approach should be chosen close to the lateral fissure to facilitate the opening of the lateral fissure to search for the aneurysm after hematoma removal. Separating directly between the veins of the lateral fissure to access the hematoma is also a good option. In fact, the distal approach is more often chosen for unruptured aneurysms or for aneurysms that do not bleed much after rupture. After the cranium, it is appropriate to find the optic nerve first to open the lateral carotid pool, release cerebrospinal fluid and wait for the cerebral pressure to be lowered, and then open the lateral fissure from the distal end of the lateral fissure to the pterygoid sinus and the lateral fissure vein connected to the vein stop. Separating the lateral fissure from distal to proximal to hit the lateral fissure is easy to operate, and after finding the Ml segment in the deep part, the bifurcation and aneurysm are then searched. All three surgical approaches are from the pterygoid point, but the skin flap incision and bone flap tend to be on the face side, and the length of the posterior lateral fissure opening varies in the human skull. When separating the lateral fissure, the frontal side should be chosen. Given that the pterygoid parietal sinus is connected to the vein of the lateral fissure, pulling the lateral fissure to the side when separating it on the frontal side, with less force, reduces the chances of injury to the pterygoid parietal sinus. Vascular injury should be prevented when separating the lateral fissure, including the lateral fissure vein, branchial arteries, and thalamic striatal arteries. This is especially important when SAH or hematoma formation occurs. These vessels may be damaged or occluded when the lateral fissure is isolated and when the hematoma is removed with suction. Cerebral traction should not be used with excessive force, especially since compression of the lateral fissure vein tends to cause localized bruising and rupture. Bipolar electrocoagulation should be used as little as possible or not at all, and the cerebral pressure plate should only be used to prevent the brain tissue from collapsing. The lateral fissure vein is divided into the superficial lateral fissure vein and the deep lateral fissure vein. Most of the superficial temporal veins pass from the glabella and enter the parietal and cavernous sinuses by merging with the Labb6 and T4fenl veins. The deep lateral fissure vein, formed by the merging of the insula veins, merges with the inferior striatal vein and crosses the path with the Ml in the superior insula, and should be protected as much as possible in case of injury as impaired consciousness and hemiparesis may occur. C. Precautions in aneurysm exposure and clamping The key to exposing the aneurysm is not to touch the rupture point of the aneurysm, which should be stripped at the neck of the aneurysm. When the top of the aneurysm is embedded in the brain, the rupture site is adherent to the cerebral attachment point, at this time, suctioning off a small part of the brain tissue around the aneurysm and preserving the brain tissue adherent to the rupture port is necessary.6 When the top of the aneurysm is adherent to the branchial small actinic dolphins, it should be cut off after electrocoagulation, and the fibrous adherence should be sharply cut off. When adherent to brain tissue, it should be separated bluntly. The purpose of separation is to increase the space, so that the aneurysm is completely free and exposed in the surgical field, so that not only can the aneurysm be satisfactorily clamped, but also to avoid accidental clamping of blood vessels, especially the dorsal blood vessels of the aneurysm. Temporary intraoperative block is not used as much as possible and is actually feasible in most cases. Temporary blockade should be performed at a site without atherosclerosis and without a perforating artery. Restricted segmental arterial yellow plaques are a manifestation of atherosclerosis and are prone to intimal injury and occlusion during temporary blockade. Despite the low pressure of the temporary blocking clip, occlusion can also occur in the perforating branch, with corresponding complications. If a temporary block is performed, it should be limited to 10 minutes. Cerebroprotective agents such as low-molecular dextrose, barbiturates, hormones, and mannitol should be given even if the duration is short. When the temporary blockade exceeds 10 min, the tumor clamp should be released to allow reperfusion of peripheral blood flow before the temporary blockade is performed. There was no significant difference in the postoperative effect between the temporary blockade within the standard time and the two-comparison without temporary blockade. After aneurysm clamping, the aneurysm neck clamping status was observed from different angles by plucking the$-aneurysm with a stripper, especially to observe whether there was any stenosis and occlusion of the Ml and M2 branches, which was the most common and major cause of cerebral infarction. In the process of aneurysm clamping, stenosis of the aneurysm-carrying artery is more common, because the aneurysm clamp is biased toward the root of the aneurysm neck, resulting in a decrease in the stenosis of blood flow in the Ml and M2 segments. From the position of aneurysm clamp, aneurysm clamp is biased toward the aneurysm side, the aneurysm is easy to recur, and biased toward the side of the carrier artery, it is easy to stenosis, so it is very important to be “moderate”; from the method of clamping, perpendicular to the aneurysm neck, there is less chance of stenosis, and with windowed aneurysm, there is more chance of stenosis in parallel; from the state of carrier artery, there are nodal and segmental stenosis, and there is more chance of stenosis. In terms of the status of the aneurysm-carrying artery, the stenosis of aneurysms with segmental atherosclerosis (yellow plaques on the arterial wall) is more likely to be caused by the clamping of the aneurysm-carrying artery, while the stenosis of the normal blood vessels is less likely. Avoid plastic stenosis during surgery for large and giant aneurysms Large and giant aneurysms are often unruptured aneurysms with wide necks, thick walls and high tensions. They can be divided into two types: thrombosed aneurysms and thrombosed aneurysms. Non-thrombotic aneurysms can be temporarily isolated; then puncture the aneurysm cavity decompression, the aneurysm plastic clamping; thrombotic aneurysms, the aneurysm will be incised to remove the canonical thrombus in the aneurysm cavity, the aneurysm plastic clamping, however, regardless of the type of aneurysm, the use of direct clamping or the use of plastic clamping method, there is a risk of formation of stenosis caused by postoperative infarction, so the intraoperative must be prepared to monitor the equipment, otherwise, this type of surgery can not be carried out. equipment, otherwise, this type of surgery cannot be performed. These include intraoperative DSA, intraoperative venous fluorescein angiography, neuroendoscopy, intraoperative electroencephalography, somatosensory evoked potentials, and microvascular Doppler. One or both of these devices are required to prevent stenosis during aneurysm clamping. Among the multiple monitoring techniques, microvascular Doppler is low cost, time-consuming, easy to use, reliable, and reusable, and therefore is often used as the preferred monitoring method during aneurysm clamping.