The goals of this study were to evaluate the extent of resection (EOR) obtained with an occipital interhemispheric transtentorial approach (OITA) in a series of pediatric patients with pineal region tumors and to define preoperative radiological factors predictive of the EOR.

This is a retrospective cohort study of a series of pediatric patients with pineal tumors who underwent surgery through a microsurgical OITA performed by the senior author during the period from January 2006 to January 2020. The tumor volume was measured preoperatively, and then on sagittal midline cuts the authors identified the most cranial point of the torcular Herophili (defined as the “Herophilus point”) and the lowest point of the inferior profile of the vein of Galen (defined as the “Galen point”). The line joining these two points (defined as the "Herophilus-Galen line" [H-G line]) was used to identify the "Herophilus-Galen plane" (H-G plane) perpendicular to the sagittal plane. Tumor volumes located below and above this plane were measured. EOR was evaluated by measuring residual tumor volume visible on T1 volumetric injected sequences of immediate postoperative MRI.

Thirty patients were selected for study inclusion. The preoperative mean tumor volume was 15.120 cm³ (range 0.129–104.3 cm³). The mean volumes were 2.717 cm³ (range 0–31 cm³) above the H-G plane and 12.40 cm³ (median 5.27 cm³, range 0.12–72.87 cm³) below the H-G plane. Three patients underwent only biopsy. Of the remaining 27 patients, gross-total resection (GTR; 100% tumor volume) was achieved in 20 patients (74%). In the remaining 7 patients, the mean residual tumor volume was 7.3 cm³ (range 0.26–17.88 cm³). In 3 of these patients, GTR was accomplished after further surgical procedures (1 in 2 patients, 3 in 1 patient) for an overall GTR rate of 85.18%. Larger tumor volume was significantly associated with incomplete resection (p < 0.001). A tumor volume ≤ 2 cm³ above the H-G plane (p = 0.003), linear extension ≤ 1 mm above the H-G line, and pineal histology were predictive of GTR at first OITA procedure (p = 0.001).

The H-G line is an intuitive, easy-to-use, and reliable indicator of the superior anatomical limit of visibility during the microsurgical OITA. This anatomical landmark may be useful as a predictor of EOR for pineal tumors performed through this approach. The main limitations of this study are the small number of patients and the exclusively pediatric age of the patient population.

本研究的目的是评估在一系列松果体区肿瘤儿科患者中通过枕部纵裂经天幕入路 (OITA) 获得的切除范围 (EOR)，并确定预测 EOR 的术前放射学因素。

这是一项回顾性队列研究，对 2006 年 1 月至 2020 年 1 月期间通过由资深作者进行的显微外科 OITA 进行手术的一系列松果体肿瘤儿科患者进行了手术。术前测量了肿瘤体积，然后测量了矢状中线切口作者确定了环状 Herophili 的最颅点（定义为“Herophilus 点”）和 Galen 静脉下部轮廓的最低点（定义为“Galen 点”）。连接这两个点的线（定义为“Herophilus-Galen 线”[HG 线]）用于识别垂直于矢状面的“Herophilus-Galen 平面”（HG 平面）。测量了位于该平面下方和上方的肿瘤体积。

选择了 30 名患者进行研究。术前平均肿瘤体积为 15.120 cm ³（范围 0.129-104.3 cm ³）。平均体积在 HG 平面上方为 2.717 cm ³（范围 0-31 cm ³），在 HG 平面下方为 12.40 cm ³（中值 5.27 cm ³，范围 0.12-72.87 cm ³）。三名患者仅接受了活检。在其余 27 名患者中，20 名患者（74%）实现了大体全切除（GTR；100% 肿瘤体积）。在其余 7 名患者中，平均残留肿瘤体积为 7.3 cm ³（范围 0.26–17.88 cm ³）。其中 3 名患者在进一步手术后完成 GTR（2 名患者中有 1 名，1 名患者中有 3 名），总 GTR 率为 85.18%。较大的肿瘤体积与不完全切除显着相关（p < 0.001）。HG 平面上方≤ 2 cm ³的肿瘤体积(p = 0.003)、HG 线上方 ≤ 1 mm 的线性延伸和松果体组织学可预测第一次 OITA 手术时的 GTR (p = 0.001)。

HG 系列是显微外科 OITA 过程中直观、易于使用且可靠的能见度解剖极限的指示器。这个解剖标志可能有助于预测通过这种方法进行的松果体肿瘤的 EOR。本研究的主要局限性是患者人数少，且患者人群仅为儿科年龄。