Anatomical Assessment on Endoscopic Occipital Transtentorial Approach for Pineal Region Tumors

With recent advancements in neuroendoscopic surgery enabling smaller openings, the role of preoperative evaluation has become increasingly important. Endoscopic surgery has demonstrated particular efficacy in the occipital transtentorial approach (OTA) for pineal region tumors. This study evaluated anatomical factors influencing endoscopic OTA performance and established criteria for optimal side selection. This retrospective study included 150 patients who underwent venous-phase head CT angiography between November 2020 and March 2022. Venous sinus configurations and their relationships with falx cerebri and tentorium cerebelli were evaluated. Surgical parameters, including occipital lobe retraction, operative axis angle, and tentorial incision, were measured and statistically analyzed. The optimal endoscopic OTA side was determined based on falx deviation and transverse sinus laterality. Occipital lobe retraction was significantly reduced when approaching from the side of falx deviation, with leftward deviation in 70% and rightward in 30%. Transverse sinus laterality was identified in 78%; approaching from the non-dominant side allowed for smaller operative axis angles but required longer tentorial incisions. The falx deviated toward the non-dominant transverse sinus side with an odds ratio of 6.55, and the optimal endoscopic OTA side was left in 61.3%. Superior sagittal sinus splitting with falx attachment to the dominant branch was found in 10.7%, and these patients required longer occipital lobe retraction even on the optimal side. This study reported that anatomical variations, including falx deviation, transverse sinus laterality, and superior sagittal sinus splitting, significantly influence endoscopic OTA feasibility. These results may contribute to optimizing endoscopic surgical strategies.