The Drainage of the Superficial Middle Cerebral Vein and Preservation of Vein in an Anterior Transpetrosal Approach

Background: The drainage of the superficial middle cerebral vein (SMCV) is classified into four subtypes. Extradural procedures in an anterior transpetrosal approach (ATPA) may interrupt the route of drainage in the case of the sphenobasal type or the sphenopetrosal type. In this study, we evaluated the SMCV patterns and considered the method of preserving vein drainage in an ATPA

Materials and Methods: We classified the SMCVs based on Hacker's classification by using three-dimensional CT angiography (3DCTA).

Results: The drainage patterns of the SMCV were examined in 128 sides of the 64 patients. The SMCVs were classified into the cavernous sinus type in 82 cases, the sphenobasal type in 29 cases, the sphenopetrosal type in 19 cases and the undeveloped type in 14 cases. There are 2 cases that could not be precisely classified into Hacker's classification. We found the veins which could interrupt the corridor of an ATPA in 52 sides. To preserve such veins, we first visualize the vein subdurally to identify whether it is vein or sinus. Then, we determine the area where the dura can be peeled and modify the dural incision if necessary.

Conclusion: The veins interrupting the corridor of an ATPA can be predicted on preoperative 3DCTA. To avoid venous complication, venous drainage should be preserved as far as possible.