Abstract：
OBJECTIVE: Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor\'s relationship to neurovascular structures and assess correlation with postoperative outcomes.
METHODS: In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor.
RESULTS: The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission.
CONCLUSIONS: The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.
METHODS: In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor.
RESULTS: The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission.
CONCLUSIONS: The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.
摘要：
目的：在枕骨大孔脑膜瘤（FMMs）的手术切除过程中，靠近关键神经血管结构会造成重大障碍，从而损害治疗效果。我们提出了一种新的分类来定义肿瘤与神经血管结构的关系，并评估与术后结果的相关性。
方法：在这篇回顾性综述中，连续41例患者通过远外侧入路进行了FMM的初次切除。根据肿瘤-神经血管束结构定义的组包括1型，束腹至肿瘤；2a-c型，捆绑上级，劣等,或张开，分别为3型，背侧束；和4型，被肿瘤包裹的神经和/或椎动脉。
结果：41例患者（29-81岁）的最大肿瘤直径平均为30.1mm（12.7-56mm）。术前,17例（41%）患者有颅神经（CN）功能障碍，12（29%）有运动无力和/或脊髓病，和9（22％）有感觉缺陷。肿瘤类型与手术结果相关：特别是，类型4显示总切除率较低（65％），术后即刻CN结果较差。长期发现显示2型、3型和4型显示出更高的永久性颅神经病的发生率。尽管4型肿瘤患者的ICU和住院时间总体较高，肿瘤构型和术后并发症发生率及30天再入院率无差异.
结论：在此提出的分类中，四种主要类型的FMM反映了手术难度和预后的逐渐增加。需要在更大的队列中进行进一步的研究，以确认其在预测术后结果和指导管理决策方面的可靠性。
方法：在这篇回顾性综述中，连续41例患者通过远外侧入路进行了FMM的初次切除。根据肿瘤-神经血管束结构定义的组包括1型，束腹至肿瘤；2a-c型，捆绑上级，劣等,或张开，分别为3型，背侧束；和4型，被肿瘤包裹的神经和/或椎动脉。
结果：41例患者（29-81岁）的最大肿瘤直径平均为30.1mm（12.7-56mm）。术前,17例（41%）患者有颅神经（CN）功能障碍，12（29%）有运动无力和/或脊髓病，和9（22％）有感觉缺陷。肿瘤类型与手术结果相关：特别是，类型4显示总切除率较低（65％），术后即刻CN结果较差。长期发现显示2型、3型和4型显示出更高的永久性颅神经病的发生率。尽管4型肿瘤患者的ICU和住院时间总体较高，肿瘤构型和术后并发症发生率及30天再入院率无差异.
结论：在此提出的分类中，四种主要类型的FMM反映了手术难度和预后的逐渐增加。需要在更大的队列中进行进一步的研究，以确认其在预测术后结果和指导管理决策方面的可靠性。
