Evaluation of Venous Structures that Are Involved in Transsylvian Approach Using 3D Rotational Venography

Abstract

In the transsylvian (TS) approach, as characterized by clipping surgery, the presurgical visualization of the superficial middle cerebral vein (SMCV) can help change the surgical approach to ensure safe microsurgery. Nevertheless, identifying preoperatively the venous structures that are involved in this approach is difficult. In this study, we investigated the venous structures that are involved in the TS approach using three-dimensional (3D) rotational venography (3D-RV) and evaluated the effectiveness of this method for presurgical simulation. Patients who underwent 3D-RV between August 2018 and June 2020 were involved in this retrospective study. The 3D-RV and partial maximum intensity projection images with a thickness of 5 mm were computationally reconstructed. The venous structures were subdivided into the following three portions according to the anatomic location: superficial, intermediate, and basal portions. In the superficial portion, predominant frontosylvian veins were observed on 31 (41%) sides, predominant temporosylvian veins on seven (9%) sides, and equivalent fronto- and temporosylvian veins on 28 (37%) sides. The veins in the intermediate (deep middle cerebral and uncal veins) and basal portions (frontobasal bridging veins) emptied into the SMCV on 57 (75%) and 34 (45%) sides, respectively. The 3D-RV images were highly representative of the venous structures observed during microsurgery. In this study, 3D-RV was utilized to capture the details of the venous structures from the superficial to the deep portions. Presurgical simulation of the venous structures that are involved in the TS approach using 3D-RV may increase the safety of microsurgical approaches.

Keywords: 3D rotational venography; clipping surgery; microsurgery; superficial middle cerebral vein; transsylvian approach.

Fig. 1

Classification of the venous structures that are involved in the transsylvian approach. The superficial middle cerebral veins were classified into three portions, and drainage patterns were evaluated. SMCV: Superficial middle cerebral vein, DMCV: Deep middle cerebral vein, UV: Uncal vein, FBBV: Frontobasal bridging vein, PP: Pterygoid plexus, SPS: Superior petrosal sinus

Fig. 2

Illustrative Case 1. A 63-year-old woman had an unruptured aneurysm of the left middle cerebral artery (MCA). (A; anteroposterior view) Three-dimensional rotational angiography (3D-RA) imaging confirmed the left MCA aneurysm. (B; anteroposterior view) Examination with three-dimensional rotational venography (3D-RV) imaging showed that the superficial middle cerebral vein (SMCV; arrow) was Type A without the temporosylvian vein, whereas the deep middle cerebral vein (DMCV; arrowhead) and frontobasal bridging vein (FBBV; double arrowhead) emptied into the SMCV, and the SMCV emptied into the sphenoparietal sinus (double arrow). (C) The composite image of 3D-RA and 3D-RV findings revealed that the DMCV (arrowhead) ran behind the aneurysm (asterisk). The presurgical simulation was planned as follows. First, we dissected the temporal side of the SMCV (dotted line in B) to sufficiently expand the Sylvian fissure. Next, we preserved the DMCV during aneurysm clipping. (D) Intraoperative findings showed that the SMCV (arrow) on the brain surface was approximately consistent with the 3D-RV findings. Then, we dissected the temporal side of the SMCV (dotted line). (E) The FBBV (double arrowhead) from the frontal base emptied into the SMCV (arrow) just before the SMCV drained into the sphenoparietal sinus. (F) Once the Sylvian fissure was opened widely, the DMCV (arrowhead) was noted to run behind the MCA and empty into the SMCV. (G) Finally, the Sylvian fissure was deployed without venous damage by dissection from the temporal side of the SMCV, and the aneurysm was safely clipped. Te: temporal lobe, Fr: frontal lobe

Fig. 3

Illustrative Case 2. A 75-year-old woman had a recurrent aneurysm of the left internal carotid-posterior communicating artery (IC-PC). (A) Three-dimensional rotational angiography (3D-RA) confirmed the recurrent left IC-PC aneurysm following coil embolization and compaction (asterisk). (B) Three-dimensional rotational venography (3D-RV) showed that the superficial middle cerebral vein (SMCV; arrow) was Type B with dominance of the temporal lobe side. The deep middle cerebral vein (DMCV; arrowhead) and frontobasal bridging vein (FBBV; double arrowhead) merged into the SMCV, and the SMCV drained into the sphenoparietal sinus (double arrow). (C) In the presurgical simulation, we planned to dissect SMCV between the frontosylvian vein and the temporosylvian vein (dotted line). We expected that the DMCV and FBBV may interfere with the surgical field during frontal lobe retraction. (D) Intraoperative findings on the SMCV (arrow) on the brain surface were consistent with those of 3D-RV. We dissected the frontal side of the SMCV (dotted line) in the presurgical simulation. (E) Arachnoid dissection was performed on the frontal side of the SMCV, as per preoperative simulation, but the frontal (black arrowhead) and temporal SMCVs (double black arrowhead) were cross-linked on the dissection line (black arrow). (F) The Sylvian fissure could be developed by dissection from the frontal side of the SMCV. (G) The FBBV (double arrowhead) and DMCV (arrowhead) merged into the SMCV. Finally, we could safely approach the aneurysm. Te: temporal lobe, Fr: frontal lobe