岩斜区脑膜瘤术中外展神经的保护

刘宁 闫长祥 (首都医科大学三博脑科医院神经外科，北京 100093)

岩斜区脑膜瘤术中外展神经的保护

刘宁 闫长祥*
(首都医科大学三博脑科医院神经外科，北京 100093)

目的总结30例岩斜区脑膜瘤手术患者的临床资料，以期提高岩斜区脑膜瘤的切除程度，并降低外展神经的损伤。方法总结30例岩斜脑膜瘤的临床特点、手术经验及外展神经受损情况，探讨Dorello's管区病理解剖特点与岩斜区脑膜瘤的关系。结果30例岩斜区脑膜瘤，<2.5 cm者6例，2.5～3.5 cm者16例，>3.5 cm者8例。术后出现外展神经功能障碍者<2.5 cm者0例，2.5～3.5 cm者5例，>3.5 cm者4例。暂时性外展神经功能障碍者7例，永久性障碍者2例。结论岩斜区脑膜瘤术中外展神经出脑干端、穿岩斜硬脑膜端容易受损伤。提高对Dorello's区解剖认识、肿瘤的早期发现、良好的肿瘤暴露、神经粘连处的锐性分离等，有助于切除肿瘤并减少外展神经的医源性损伤。

岩斜脑膜瘤; Dorello's管; 外展神经

Dorello's管为外展神经穿斜坡硬脑膜处至其穿蝶岩韧带(Gruber's韧带)下方的纤维管道，其内走行外展神经。Dorello's管是颅底外科的重要结构，该区域位置深在、周围解剖关系复杂，许多颅底肿瘤尤其是岩斜区脑膜瘤的手术治疗都会涉及到该区域[1～3]。我们总结30例岩斜脑膜瘤手术患者的临床资料，分析外展神经易损伤的因素，以期深化理解该区域解剖特点，提高岩斜区脑膜瘤的切除程度并降低外展神经的损伤机率。

对象与方法

一、一般资料

30例岩斜区脑膜瘤，男性12例，女性18例。平均年龄42.5岁。

二、临床表现

头痛15例，肢体运动障碍8例，颜面部感觉障碍6例，共济运动障碍8例，眼球运动障碍4例，声音嘶哑1例。

三、影像学检查

30例肿瘤 CT上多呈等或稍高密度；MRI多呈等或稍长T1信号、等长T2信号，边界清楚，多呈类圆形，打药后病灶多呈均匀明显强化(图1,3)。肿瘤体积：<2.5 cm者6例，2.5～3.5 cm者16例，>3.5 cm者8例。

四、手术治疗

手术路径：颞下入路14例，乙状窦前入路7例，颞下联合乙状窦后入路6例，乙状窦后入路3例。术中所见：岩斜脑膜瘤多呈膨胀性生长，术中发现其基底多位于鞍背、后床突、海绵窦后壁、岩尖等处硬脑膜且与之粘连紧密。肿瘤多呈灰黄色、黄白色，质地通常硬韧，质地柔软者很少，血供通常非常丰富。体积较小者一般与周围神经、血管、脑干等粘连较轻，随着病灶体积增大，粘连亦随之加重。动眼神经通常位于肿瘤顶部，三叉神经位于外侧略上方，外展神经通常位于肿瘤腹侧底面，经常需将肿瘤全部切除后才能显露该神经全貌(图2)。体积较大肿瘤一般将脑池段外展神经向对侧推挤、粘连显著并侵及Dorello's管外口(图4)。

结 果

全切21例(70%)，近全切8例(27%)，大部切除1例(3%)，病理检查为纤维型脑膜瘤(图5)。术后外展神经功能障碍：<2.5 cm者0例，2.5～3.5 cm者5例，>3.5 cm者4例。暂时性外展神经功能障碍者7例(3个月至半年得以恢复)，永久性障碍者2例(超过1年未好转)。术后无1例死亡患者，暂时性气管切开1例，30例患者均有随访，随访3年11个月，平均随访2年3个月，无一例复发，颜面部感觉障碍者8例，面瘫者4例，轻度偏瘫者3例，动眼神经障碍者2例。

图1 术前MRI轴位增强扫描

Fig 1 Pre-operative axial view of contrast MRI

The arrow showed that the tumor was located on the left side of the petrous apex and the upper clivus, with a diameter of 2.0 cm, even texture, clear boundary and medium blood supply. The brain stem was slightly compressed.

图2 行左侧枕下乙状窦后入路肿瘤全部切除后的术中影像

Fig 2 Intra-operative image after tumor total removal via left post-sigmoid sinus approach

Abducent nerve was beneath the base of the tumor.

图3 术前MRI轴位增强扫描

Fig 3 Pre-operative axial view of contrast MRI

The arrow showed that the tumor was large in size with a diameter of about 4.5 cm, uniform texture, clear boundary and abundant blood supply. The tumor base was wide and invaded the whole slope. The brainstem and basilar arteries were significantly compressed and deformed, shifted toward the contralateral side.

图4 行右侧颞下入路肿瘤全部切除后术中影像

Fig 4 Intra-operative image after tumor total removal via right sub-temporal approach

The tumor invaded the bilateral Dorello's cannal where the abducent nerve pierced the clival dura. The basilar artery was significantly shifted to the contralateral side.

图5 术后病理图片(HE, ×400)

Fig 5 Post-operative pathological image(HE, ×400)

Fibrous meningioma with scattered calcification (WHO I grade). Nuclear had less atypia, mostly was ovoid or fusiform, and arranged loosely. A large number of glial fibrillary components arranged around the tumor cells.

讨 论

我们将外展神经分为脑池段、Dorello's管段、海绵窦段、眶上裂段及眶内段。Dorello's管为介于岩尖和上斜坡外侧缘之间的椭圆形骨纤维性管道，内含静脉性血窦，其内穿行外展神经。Dorello's管上壁为蝶岩韧带，该韧带的重要作用是固定并保护外展神经[4～7]。岩斜脑膜瘤体积较大时，尤其是>3.5 cm者，可将Dorello's管内外展神经移位，蝶岩韧带的切割力会损伤外展神经，术前患者即可表现外展受限。脑池段外展神经的外层鞘膜通常与蝶岩韧带、岩尖处的硬脑膜紧密粘连。在电灼切断岩斜区硬脑膜肿瘤基底时如电灼海绵窦后壁内侧三角硬脑膜时，热损伤可能会伤及该段外展神经，适度的电灼且电灼过程不断滴水降温有助于外展神经的保护。岩斜区脑膜瘤通常呈膨胀型生长，朝对侧方向推挤脑池段外展神经，该段神经活动度较大，且肿瘤与神经之间通常有双层蛛网膜结构，肿瘤体积不是特别巨大时，通常较易分离。

结合临床经验，我们认为肿瘤直径<2.5 cm的岩斜脑膜瘤(图1,2)，外展神经多可不被侵及，术后很少发生眼球外展受限；肿瘤直径处于2.5～3.5 cm，肿瘤通常推挤脑池段外展神经并有不同程度的粘连，术后可能会有一定程度神经功能障碍；而当肿瘤直径大于3.5 cm时(图3,4,5)，肿瘤会进一步侵及并环形包绕穿斜坡硬脑膜处的外展神经，术后较易发生其功能障碍。后床突下方(19.2±2.6)mm为外展神经穿斜坡硬脑膜处，外展神经出桥延沟处及穿斜坡硬脑膜处位置恒定，术中较易损伤，电灼外展神经穿斜坡硬脑膜周围肿瘤基底时要格外小心。

根据肿瘤的生长特点，结合术者的手术经验，选择合适的手术入路暴露肿瘤，术中肿瘤与外展神经粘连处尽可能多的锐性分离，有助于降低神经损伤。岩斜脑膜瘤通常向周围推挤颅神经，外展神经通常位于肿瘤底面内侧深部，脑池段多有不同程度移位，故不管是幕上入路还是幕下入路，通常需将肿瘤全部切除后方可显露其全貌。故在全切肿瘤前提前判断Dorello's管、外展神经的位置是非常重要的[8～10]。我们手术经验认为，颞下入路暴露过程中，弓状隆起、三叉神经穿Meckle's孔处、后床突及鞍背是固定结构，而经岩骨后方暴露肿瘤过程中内耳门、颈静脉孔等是固定结构，通过这些结构可预先判断外展神经穿斜坡硬脑膜位置、Dorello's管等。病理解剖中，Dorello's管及蝶岩韧带上方为受压位置上抬的动眼神经、后交通动脉，蝶岩韧带外侧端紧邻受压朝侧方移位的三叉神经脑池段。术中分块切除肿瘤，有条件时用超声吸引器，瘤内减压减少肿瘤体积有助于上述神经的保护。外展神经出脑干端、穿岩斜硬脑膜端(进Dorello's管前)位置固定，这两处更容易受损，故沿肿瘤内侧底面分离时，尽量与斜坡纵轴方向游离，减少横向方向的分离动作。岩斜脑膜瘤外展神经通常向内侧横向移位，外展神经在横轴上的张力是饱满的，尤其是在其穿斜坡硬脑膜处的横向操作更易加重其损伤[11～13]。

Dorello's管是颅底外科的重要解剖标志，也是定位外展神经的标志性结构。岩斜区脑膜瘤经常侵及该区域，术中外展神经出脑干端、穿岩斜硬脑膜端容易受损伤，提高对Dorello's区解剖认识、肿瘤的早期发现、良好的肿瘤暴露、神经粘连处的锐性分离等，有助于切除肿瘤并减少外展神经的医源性损伤。

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Protectionofabducentnerveintheoperationofpetroclivalmeningioma

LIUNing,YANChangxiang

DepartmentofNeurosurgery,SanboBrainHospital,CapitalMedicalUniversity,Beijing100093, China

ObjectiveThe clinical data of 30 cases of petroclival meningioma have been summarized in order to improve the resection degree of petroclival meningiomas and reduce the abducent nerve injury.MethodsThe clinical characteristics, surgical techniques and abducent nerve damages were discussed and the relationship between the microanatomy of Dorello's cannal and petroclival meningioma was investigated.ResultsIn 30 cases of petroclival meningiomas, tumor diameter <2.5 cm was in 6 cases, 2.5～3.5 cm in 16 cases, and >3.5 cm in 8 cases. After operation for patients with tumor diameter <2.5 cm, no abducent nerve dysfunction occurred; for patients with tumor diameter of 2.5～3.5 cm, there was 5 cases of abducent nerve dysfunction and for tumor diameter >3.5 cm, there were 4 cases. There were 7 cases of temporary dysfunction and 2 cases of permanent injury.ConclusionDuring the operation of petroclival meningioma, abducent nerve is prone to injury in the places where it originates from the pontomedullary sulcus and pierces the petroclival dura. Better knowledge of Dorello's cannal, early diagnosis and good exposure of the tumor, and acute separation in the adhesion will be helpful for the remove of the tumor and reduction of the iatrogenic injury of abducent nerve.

Petroclival meningioma; Dorello's cannal; Abduncent nerve

1671-2897(2016)15-156-03

·论著·

R 739

A

刘宁，主治医师，医学硕士，E-mail:liuning301@aliyun.com

*通讯作者： 闫长祥，主任医师，医学博士，E-mail: yancx65828@163.com

2015-02-15;

2015-04-10)