Exploitation of Simple Classification and Space Created by the Tumor for the Treatment of Foramen Magnum Meningiomas

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• 作者：Hitoshi Yamahata¹ ; ^{yamahatad3@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Satoshi Yamaguchi² ; Masakazu Takayasu³ ; Koji Takasaki⁴ ; Koji Osuka³ ; Masahiro Aoyama³ ; Muneyoshi Yasuda³ ; Hiroshi Tokimura¹ ; Kaoru Kurisu² ; Kazunori Arita¹
• 关键词：Craniovertebral junction ; Foramen magnum ; Meningioma ; Posterolateral approach ; Transcondylar fossa
• 刊名：World Neurosurgery
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：87
• 期：Complete
• 页码：1-7
• 全文大小：3959 K

文摘

The resection of foramen magnum meningiomas (FMMs) presents neurosurgical challenges. We propose a simple classification of the tumor location and the operating space created by the tumor to help treatment planning.

Methods

We retrospectively analyzed 16 FMMs and divided them into 3 groups based on the tumor location—clival, foraminal, and atlantal tumors. The distance between the condyle and the neuraxis at the level of the foramen magnum was measured and defined as the available operative space (AOS). We also reviewed intraoperative video recordings to assess the surgical exposure of the tumor by the space created by the FMM and compared it with the AOS.

Results

There were 4 clival, 8 foraminal, and 4 atlantal tumors. The AOS of the clival tumors was 10 mm ± 1.7, the AOS of the foraminal tumors was 18 mm ± 3.7, and the AOS of the atlantal tumors was 12 mm ± 2.1. All foraminal and atlantal tumors could be detached without a brain retractor. Because a major portion of the clival tumors was covered by the spinomedullary junction, a brain spatula was needed to obtain the required surgical space. The difference in AOS between clival and foraminal/atlantal tumors was statistically significant (P = 0.044). Although 4 patients experienced postoperative complications, the average postoperative Karnofsky performance scale score improved. The surgical complication rate was significantly lower in foraminal and atlantal FMMs than in clival FMMs (P = 0.027).

Conclusions

The simple classification of the tumor location helped to assess surgical difficulties. Knowledge of the space created by the FMMs between the condyle and the neuraxis is useful for planning the approach strategy, especially for estimating the available working space without resection of the occipital condyle.