Department of Neurosurgery, Juntendo University Faculty of Medicine, Tokyo, Japan.
Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
World Neurosurg. 2024 Sep;189:e1057-e1065. doi: 10.1016/j.wneu.2024.07.081. Epub 2024 Jul 14.
The rhomboid lip is a neural tissue encountered during cerebellopontine angle surgery, with differing shape and extent among individuals. This study aimed to investigate the variation of rhomboid lips during posterior fossa surgery.
In this retrospective study, we examined posterior cranial fossa surgeries performed using a retrosigmoid approach. Rhomboid lips were classified according to thickness, extent, and appearance, with some subjected to histological analysis. T2-weighted magnetic resonance imaging of rhomboid lips was conducted.
Among 304 surgeries, rhomboid lips were observed in 75 patients who underwent schwannoma or meningioma resection, facial spasm-related neurovascular decompression, and other surgeries (37, 2, 32, and 4 patients, respectively). Rhomboid lips were categorized based on apparent thickness: thin membranous type, resembling an arachnoid membrane, and thick parenchymal type. Rhomboid lip extension was classified by position relative to the choroid plexus: nonextension, lateral extension, and jugular foramen (41, 22, and 12 patients, respectively). Veins were observed on the rhomboid lip surface in 37 cases. The rhomboid lip was visible in only 1 case (parenchymal jugular foramen type) on magnetic resonance imaging. Histologically, the rhomboid lip comprised an ependymal cell layer, a glial layer, and connecting tissue. The glial layer thickness determined the rhomboid lip thickness, which was greater in the parenchymal type than in the membrane type. In 42 patients, the rhomboid lip was dissected with no complications observed.
Morphological classification of the rhomboid lip and understanding of its anatomical details contribute to safe surgical field development for neurosurgeons.
菱形唇是桥小脑角手术中遇到的一种神经组织，个体之间形状和范围存在差异。本研究旨在探讨后颅窝手术中菱形唇的变化。
在这项回顾性研究中，我们检查了使用乙状窦后入路进行的后颅窝手术。根据厚度、范围和外观对菱形唇进行分类，部分进行组织学分析。对菱形唇进行 T2 加权磁共振成像。
在 304 例手术中，观察到 75 例接受神经鞘瘤或脑膜瘤切除术、面肌痉挛相关神经血管减压术和其他手术的患者存在菱形唇（分别为 37、2、32 和 4 例患者）。根据明显厚度将菱形唇分类：薄膜型，类似于蛛网膜；厚实质型。根据与脉络丛的相对位置将菱形唇延伸分类：无延伸、外侧延伸和颈静脉孔（分别为 41、22 和 12 例患者）。在 37 例中观察到菱形唇表面有静脉。仅在 1 例（实质型颈静脉孔型）磁共振成像上可见菱形唇。组织学上，菱形唇由室管膜细胞层、胶质层和连接组织组成。胶质层厚度决定了菱形唇的厚度，实质型比膜型厚。在 42 例患者中，菱形唇被解剖，未观察到并发症。
对菱形唇进行形态学分类，并了解其解剖细节，有助于神经外科医生安全地开发手术区域。
