A 3D-Computed Tomography Angiography Study to Help in Surgical Planning for Retrosigmoid Craniotomies
Aims and Objectives: It is impossible to precisely anticipate the course of the transverse and sigmoid sinuses and their individual relationship to superficial landmarks such as the asterion during retrosigmoid approaches. This study was done to determine the position of the asterion and the relationship between asterion and the transverse-sigmoid sinus junction (TSSJ) in making precise burr hole without damaging sinuses during retrosigmoid craniotomies.
Materials and Methods: Computed tomography (CT) angiography was performed in 50 patients to obtain 3D-CT volume rendering images of cranial bone and dural sinuses. After delineating the sinuses, by simple restructuring using software and opacity modulation, bone image is reinforced. Asterion type, distance from the tip of mastoid process to asterion and root of zygoma (ROZ) to asterion, and location of asterion in relation to TSSJ and distance between asterion and TSSJ were analyzed and measured.
Results: The incidence of type 1 (presence of sutural bones) in our study was 24% and type 2 (absence of sutural bones) was 76%. There was no statistically significance in the side and gender differences. The distance between the asterion and from the ROZ was 54.70 ± 3.68 on the right side and 54.32 ± 3.41 on the left side (P-0.612). The distance between asterion and tip of mastoid was 50.51 ± 2.67 on the right side and 50.12 ± 3.06 on the left side (P-0.716). The asterion was located on the T-S sinus complex in 36 (72%) cases. The asterion was below the T-S sinus complex in 13 (26%) cases, and above the T-S sinus complex in only 1 (2%) cases.
Conclusion: 3D-CT volume rendering imaging is capable of accurately visualizing the bony landmark and dural sinuses. An easy and simple restructured image provides precision and safety for the patient by ready and easy localization of asterion and TSSJ. This study was done to show that the previous cadaver-based anatomical studies can be done now in a more sophisticated and accurate manner with the latest technological advancements. This offers new options for anatomic research and morphometric investigations.
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