Dissection of the Sylvian Fissure in the Trans-sylvian Approach Based on the Morphological Classification of the Superficial Middle Cerebral Vein

Abstract

The superficial middle cerebral vein (SMCV) is one of the main factors that can impede a wide opening of the sylvian fissure. To reveal the most efficient SMCV dissection for a wide operative field while preserving the veins in the trans-sylvian approach, we retrospectively investigated the SMCVs through intraoperative video images. We characterized the SMCV as composed of the frontosylvian trunk (FST; receiving frontosylvian veins [FSVs] or parietosylvian veins [PSVs]), the temporosylvian trunk (TST; receiving temporosylvian veins [TSVs]), and the superficial middle cerebral common trunk (SMCCT; receiving both FSV/PSV and TSV), and classified the SMCVs of the 116 patients into 5 types based on the morphological classification of the SMCV. Type A SMCV (60.4%) with the SMCCT anastomosed to the frontal side had few bridging veins (BVs) between the SMCCT and the temporal side during dissection. Type B (7.8%) had the SMCCT with no anastomoses to the frontal side. In Type C (17.2%) consisting of the FST and TST and Type D (12.9%) with a merging of the vein of Trolard and Labbé posteriorly and the SMCVs dividing into the FST and the TST again proximally, there were few BVs between the FST and the TST during dissection. Finally, in Type E (1.7%) showing an undeveloped SMCV, there were no BVs between the frontal and the temporal lobes. Postoperative venous infarction occurred in 2.6%. Morphological classification of the SMCV can inform appropriate dissection line to create a wide operative field while preserving the veins in the trans-sylvian approach.

Three-dimensional Images Fusion Method Useful for Preoperative Simulation of Clipping Surgery for Cerebral Aneurysms

“…20) The main reason is that the imaging resolution in 3D RA was much higher than that in CT angiography, especially in describing cerebral veins. 21) SMCVs were precisely reproduced regardless of their variations, [12][13][14] and therefore, it was possible to dissect the sylvian fissure wide enough to expose aneurysms without crossing SMCVs in all cases. Thus, the role of CT angiography became latent in this study, but intracranial vessels provided by CT angiography worked as a reference in R. Yasuda et al…”

“…In a transsylvian approach, since the number and the course of superficial middle cerebral veins (SMCVs) vary, [12][13][14] it is important to find space between SMCVs draining from the frontal and temporal lobe, where dissection of the sylvian fissure should be performed to widely open the fissure. Superimposing 3D RA-artery enabled operators to see the order of MCA branches that operators would encounter during the sylvian fissure dissection (Fig.…”

Iatrogenic mixed pial and dural arteriovenous fistula after pterional approach for surgical clipping of aneurysm: A case report

“…According to Yasargil (1984), vascular neurosurgeons tend to dissect between the SMCV and frontal lobe during the transsylvian approach [ 27 ]. However, this may lead to unnecessary manipulation and coagulation of the fronto-sylvian bridging veins [ 11 , 12 , 17 ]. Imada et al (2021, 2019) used cadaver dissection to understand and introduce morphological patterns and classification of the SMCV based on its relationship with fronto-sylvian and temporo-sylvian veins, which is a useful reference during surgery [ 11 , 12 ].…”

“…However, this may lead to unnecessary manipulation and coagulation of the fronto-sylvian bridging veins [ 11 , 12 , 17 ]. Imada et al (2021, 2019) used cadaver dissection to understand and introduce morphological patterns and classification of the SMCV based on its relationship with fronto-sylvian and temporo-sylvian veins, which is a useful reference during surgery [ 11 , 12 ]. Unnecessary damage can be prevented by performing sylvian dissection according to the patient’s specific SMCV anatomy.…”

Usefulness of the Multimodal Fusion Image for Visualization of Deep Sylvian Veins

“…Many reports of the morphological patterns of the SSVs for dissection of the Sylvian fissure were observed. 2 ) Conversely, deep Sylvian veins, which receive tributaries from the insula and neighboring gyri and run in the lower part of the lateral sulcus, have been under-recognized because they are difficult to radiologically visualize due to their small size and individual variability. These veins occasionally limit the development of the operative field, attach to an aneurysm, and interfere with the microscope's line of view.…”