[学术前沿]南昌大学一附院洪涛团队基于内镜手术在国际上提出颅咽管瘤新分型
神外前沿讯，近日南昌大学第一附属医院神经外科主任、中国医师协会神经外科分会神经内镜专委会主任委员、中国医师协会神经内镜专委会副主任委员洪涛教授总结了2012年-2017年连续采用内镜经鼻入路切除92例颅咽管瘤的手术经验，并在国际上率先根据内镜下对肿瘤与垂体柄的关系及其起源点和生长方式的观察提出了新的分型，系统地阐述了对颅咽管瘤的理解，制定出不同亚型颅咽管瘤的鉴别诊断流程图，结果发表于Scientific Report杂志上。
Bin Tang, Shen Hao Xie, Li Min Xiao, Guan Lin Huang, Zhi Gang Wang, Le Yang,Xuan Yong Yang, Shan Xu, Ye Yuan Chen, Yu Qiang Ji, Er Ming Zeng & Tao Hong. A novel endoscopic classification for craniopharyngioma based on its origin.[J].Scientific Report: (2018) 8:10215.( DOI:10.1038/s41598-018-28282-4)
近年来，神经内镜在颅咽管瘤手术上的技术优势越来越明显，采用内镜经鼻入路切除颅咽管瘤时，借助神经内镜无死角、抵近观察的优势，可清晰辨别肿瘤与垂体柄的关系，以及肿瘤的起源和生长方式。
1、两大分型和三个亚型
基于内镜下的观察，洪涛教授提出了对颅咽管瘤的新分型：首先根据肿瘤与垂体柄的关系，颅咽管瘤可被分为中央型（图1A、B）和偏侧型（图1C、D）两种类型：中央型颅咽管瘤常在下丘脑-垂体柄轴内居中生长，无法观察到明确的起源点，而偏侧型颅咽管瘤常沿着下丘脑-垂体柄轴偏外侧生长，垂体柄被推向肿瘤一侧（前、后、左、右均可），在下丘脑-垂体柄轴上可明确观察到肿瘤的起源点。
再根据肿瘤在下丘脑-垂体柄轴上的起源点不同，偏侧型颅咽管瘤又被分为下丘脑垂体柄型（图1E）、鞍上垂体柄型（图1F）及鞍内垂体柄型（图1G）三种亚型。
下丘脑垂体柄型：起源于漏斗结节处，肿瘤可向上扩展生长侵入三脑室和/或向下扩展进入鞍上池。
鞍上垂体柄型：常起源于垂体柄的鞍上池部分的下段，肿瘤常位于鞍上池三脑室外生长。
鞍内垂体柄型：起源于垂体柄的鞍内部分，即鞍内型颅咽管瘤，肿瘤可向上生长，亦可向蝶窦、海绵窦方向生长。（图1、2）
图1：Schematic diagrams of the endoscopic subclassification of CPs. (A,B) Central type CP grows within and along the stalk and no pedicle or definite origin site can be identified, tumor is always located strictly in the midline. (C,D) Peripheral type CP arises from the stalk but expands and grows laterally in an exophytic pattern, the residual stalk is usually displaced to circumferential surface of the tumor. (E,F and G) Different origin sites of 3 subtypes of Peripheral type CPs along the pituitary stalk. (E) Hypothalamic stalk CP develops at the junction of the hypothalamus and the stalk, which usually extends up to the hypothalamus (brown arrow) and/or down to the up portion of stalk (black arrow), and usually invaded into the third ventricle. (F) Suprasellar stalk CP derives from suprasellar segment, usually low portion, of the stalk, and commonly locates extraventriclely. (G) Intrasellar stalk CP originates from the part of stalk under diaphragma, which is alsoknown as intrasellar CP. Yellow discs in schematic diagrams indicate the origin site of the tumor.
分型：
图2：Scheme of the endoscopic classification of CPs based on the relation with stalk and the origin of tumor.
2、不同分型的影像学特点
通过对26例中央型颅咽管瘤和66例偏侧型颅咽管瘤的术前影像学资料进行统计分析（表1），洪涛教授指出：由于肿瘤起源和生长方式的不同，中央型和偏侧型颅咽管瘤均具有各自的术前影像学特点。
中央型颅咽管瘤通常体积不大，冠状位MRI上可见肿瘤位置居中，（与垂体柄位置吻合），三脑室下部亦不存在偏移（图3A1），当肿瘤生长较大时，矢状位MRI上常可见肿瘤沿下丘脑-垂体柄轴在垂直方向生长，呈细长形态（图4A）。
偏侧型颅咽管瘤通常体积大于中央型，冠状位MRI上常可见肿瘤偏向一侧，三脑室下部被肿瘤推向对侧，该侧通常预示残存垂体柄所在侧（图3B1、C1），当肿瘤生长巨大时，矢状位MRI上常可见肿瘤沿水平方向生长，向前颅底、侧裂、桥前池、后颅窝等方向扩展（图5A、C）。因此通过仔细观察MRI，术前可对中央型和偏侧型颅咽管瘤作出一定的鉴别诊断。
表1：Imaging characteristics of Peripheral type and Ce ntral type CPs.
图3：Pre- and post-operative images and intraoperative findings of each subtype of CPs via endoscopic endonasal approach. (A1-6) A case of Central type CP. (A1-2) Coronal and sagittal postcontrast T1-weighted MR images showing a Central type CP which is located in the midline. (A3-4) Intraoperative photographs showing that tumor grew within and along the stalk, and the characteristic structure of stalk could be clearly identified on the surface of tumor (A3). Bilateral hypothalamus damage limited to tuber cinereum area could be seen after tumor removal (A4). (A5-6) Coronal and sagittal postcontrast T1-weighted MR images obtained after GTR. The pituitary gland was preserved and intact, but the stalk was not preserved. (B1-6) A case of Hypothalamic stalk CP. (B1-2) Coronal and sagittal postcontrast T1-weighted MR images showing a suprasellar CP located slightly toward to the left side and grows into the third ventricle, with the anterior third ventricle shifted to the right side (yellow arrowheads in B1). (B3-4) Intraoperative photographs showing that tumor originated from the junction of the hypothalamus and the stalk (white arrowheads in B3), the stalk was pushed to the right side. After tumor removal, a defect at the left side of the third ventricle floor could be found, and the remnant of stalk was pushed to the right side and connected to the right side of the third ventricle floor, with a relative normal hypothalamus at the right side (B4). (B5-6) Coronal and sagittal postcontrast T1-weighted MR images showing total tumor removal achieved. The stalk was preserved and pushed to the right side (red arrowhead in B5), the right hypothalamus was intact (blue arrowheads in B5-6).Note the vascularized nasoseptal flap at the posterior aspect of the sphenoid sinus on the sagittal image (orange arrowhead in B6). (C1-6) A case of Suprasellar stalk CP. (C1-2) Coronal and sagittal postcontrast T1-weighted MR images showing a suprasellar CP located toward to the left side, with the anterior third ventricle shifted to the right side (yellow arrowheads in C1). (C3-4) Intraoperative photographs showing that tumor derived from suprasellar segment, low portion of the stalk (black arrowheads in C3). After tumor removal, the third ventricle floor was intact, with no hypothalamus damage, and the remanent of stalk was pushed to the right side (C4). (C5-6) Coronal and sagittal postcontrast T1-weighted MR images showing total tumor removal achieved. The stalk was preserved and pushed to the right side (red arrowhead in C5), and the hypothalamus was intact (blue arrowheads in C5-6). Note the vascularized nasoseptal flap at the posterior aspect of the sphenoid sinus on the sagittal image (orange arrowhead in C6). (D1-6) A case of Intrasellar stalk CP. (D1-2) Coronal and sagittal postcontrast T1-weighted MR images showing a typical intrasellar CP. (D3-4) Intraoperative photographs showing that the solid tumor located in the sellar region. Residual pituitary gland and stalk can be seen after tumor removal (D4). (D5-6) Coronal and sagittal postcontrast T1-weighted MR images showing total tumor removal achieved. Ht, hypothalamus; Tu, tumor; Pg, pituitary gland; Ps, pituitary stalk. 3rd V., the third ventricle.
图4：Example of a Central type Cp grows longer in vertical direction. A and B: Sagittal (A) and Coronal (B) post-contrast T1-weighted MR images showing that tumor grows up to the third ventricle and down to the intrasellar region through pitiutary stalk. C and F: Intraoperative photographs showing that tumor grew within and along the stalk and down to the intrasellar region (C). The third ventricle floor was destroyed, residual pituitary gland pushed and compressed by the tumor could be seen after tumor removal (F). D and E: Sagittal (D) and Coronal (E) postcontrast T1-weighted MR images obtained after GTR demonstrating extensive, safe resection of the tumor. 3rd V., the third ventricle; Pg, pitui-tary gland.
图5：Examples of giant Suprasellar stalk CPs grow in roughly horizontal direction. (A and B) Sagittal (A) and Coronal (B) postcontrast T1-weighted MR images showing a giant Suprasellar stalk CP extends to the anterior fossa, sylvian fissure, the prepontine and posterior fossa. (C and D) Sagittal (C) and Coronal (D) postcontrast T1-weighted MR images showing a giant Suprasellar stalk CP extends to the prepontine and posterior fossa.
3、不同分型的术中特点
如同影像学所见，中央型和偏侧型颅咽管瘤的术中所见亦具有各自的特点。
3.1中央型颅咽管瘤
中央型颅咽管瘤在下丘脑-垂体柄轴内居中生长，正常的垂体柄结构已消失，在肿瘤表面常可见纵行生长的髓纹样结构（图3A3），术中垂体柄的保留率低，肿瘤常对双侧下丘脑造成浸润性损害（表2），肿瘤切除后三脑室底常开放（图3A4），因此推出中央型颅咽管瘤可能起源于漏斗结节处。当肿瘤生长巨大时，常沿下丘脑-垂体柄轴在垂体方向生长，向上可侵入三脑室，对双侧下丘脑造成损害，向下可侵入鞍内，推挤压迫垂体（图4）。
3.2偏侧型颅咽管瘤
在偏侧型颅咽管瘤的3种亚型中：
下丘脑垂体柄型起源于漏斗结节处，术中可见垂体柄常被肿瘤推向对侧，保留率较高（表2），肿瘤的基底可向上和/或向下扩展，形成宽基底，肿瘤常对同侧的下丘脑造成浸润性损害，对侧的下丘脑被推挤，保留完整，肿瘤切除后常可见同侧的三脑室底开放（图3B3、B4）；
鞍上垂体柄型常起源于垂体柄的鞍上池部分的中下段，垂体柄亦常被推向对侧，保留率亦较高（表2），肿瘤常位于三脑室外生长并推挤压迫下丘脑，而非浸润性损害（图3C3、C4）；
鞍内垂体柄型起源于垂体柄的鞍内部分，肿瘤切除过程中难以保留鞍内部分垂体柄（图3D3、D4），当肿瘤巨大且向上生长时可推挤压迫下丘脑。
在后两种亚型中，肿瘤对下丘脑的推挤压迫可分为三级，一级指肿瘤仅接触或轻度压迫下丘脑，肿瘤与下丘脑间存在蛛网膜界面；二级指肿瘤较明显压迫下丘脑，肿瘤与下丘脑间蛛网膜界面不清，分离时有较紧密粘连，但下丘脑依然能保留完整；三级指肿瘤已突破下丘脑进入三脑室，分离肿瘤过程中可见下丘脑破损，三脑室底开放（图6）。
表2：Characteristics of Central type and Peripheral type CPs
图6：Three stages in the Suprasellar stalk CPs according to the relationship between tumor and hypothalamus. (A1 and A2) Schematic drawing of a Suprasellar stalk CP in Grade 1: tumor contacts the hypothalamus but there exists a subaracnoid and pial membrane between them. (A3) The T1-GDPA image of a typical case in the sagittal plane of MR image. (A4) Intraoperative photographs showing that the third ventricle floor was thick and intact after tumor resection (yellow arrow). (B1 and B2) Schematic drawing of a Suprasellar stalk CP in Grade 2: tumor obviously pushes the hypothalamus upward with no membrane between them.(B3) The T1-GDPA image of a typical case in the sagittal plane of MR image. (B4) Intraoperative photographs showing that the third ventricle floor was thin and intact after tumor resection (red arrow). (C1 and C2) Schematic drawing of a Suprasellar stalk CP in Grade 3: tumor severely pushes the hypothalamus upward and breaks it into the third ventricle with tight adherence to the remnants of hypothalamus. (C3) The T1-GDPA image of a typical case in the sagittal plane of MR image. (C4) Intraoperative photographs showing that a defect of the third ventricle floor could be seen after tumor resection (blue arrow).
4、鉴别诊断流程图
因此，根据不同亚型颅咽管瘤的临床和术前影像学特点，以及肿瘤与垂体柄、下丘脑的关系，洪涛教授特制定出不同亚型颅咽管瘤的鉴别诊断流程图，详见图7。
图7：Illustration of the steps to diagnose the subtype of CP preoperatively and its corresponding degree of hypothalamus and stalk injury.
5、手术经验：
内镜经鼻入路切除颅咽管瘤主要利用的是视交叉-垂体柄间隙，这是到达肿瘤生长主要区域——鞍上池、三脑室最大的自然间隙，手术过程采取双人四手操作能达到显微操作原则，沿肿瘤生长轴直视肿瘤腹侧，可第一时间探查肿瘤起源，印证术前推断，并对肿瘤与周边结构粘连进行直视下分离，其中视交叉腹侧和下丘脑是开颅手术的主要盲区，内镜下的优势则更能得到凸显。
对于肿瘤起源处，如中央型和下丘脑垂体柄型的下丘脑漏斗结节部、鞍上垂体柄型的垂体柄处，肿瘤总是呈指头样浸润，应采取锐性分离；对于非肿瘤起源处，如鞍上垂体柄型和鞍内垂体柄型的下丘脑处、下丘脑垂体柄型的起源点以外的下丘脑，均呈推挤压迫关系，采取钝性分离为主。
分离过程中尽量保持原位，避免对下丘脑等重要结构的过度牵拉，4.0mm口径吸引器吸力的牵拉被认为是安全的。严格禁止盲目牵拉，在极个别极端情况下的拖拽也应当是在直视下进行，将镜子深入对准分离界面，严密观察中拖拽，而不是将镜子拿出观看已拖拽出的肿瘤。少数病例视交叉-垂体间隙较窄，而肿瘤向三脑室内突入较高者，可联合经终板入路辅助肿瘤切除。
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