**6.3 Arteries**

Detection of the ICA is challenging because it is covered with a tumor. The point is to estimate the character of MAP adhesion to the arterial wall as early as possible. Intimate fusion makes surgical separation impossible because of the risk of arterial wall damage. The so-called "proximal control" proposed by Al-Mefty is not frequently used nowadays. Comparing two approaches in the context of ICA damage risk, the intradural approach is more dangerous because of the need to go through the mass of the tumor to reach the artery wall without having a plan for dissection. In contrast, the extradural approach provides the opportunity to assess the degree of adhesion by early detection of the ICA in CS using intraoperative Doppler and visualize it at the level of the distal dural ring.

The presence of circular ingrowth of the ICA by the tumor cast doubt on attempts to separate them. Consequently, the sharp dissection of all involved vessels of the circle of Willis is preferred.

## **6.4 Veins**

Venous anatomy in this region is extremely variable. They are always fullblooded and are at high risk of being damaged. The CS is a complex of venous channels. Due to the variability of the functional role of each vein, the excision of the tumor should be conducted with maintaining the integrity of the veins. They should be cut only if there is a confidence that the vein drains the tumor. Sylvian veins could be directly drained into the CS [15].
