Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model

INTRODUCTION: The pterygopalatine fossa (PPF) is a narrow space located between the posterior wall of the antrum and the pterygoid plates. Surgical access to the PPF is difficult because of its protected position and its complex neurovascular anatomy. Endonasal approaches using rod lens endoscopes, however, provide better visualization of this area and are associated with less morbidity than external approaches. Our aim was to develop a simple anatomical model using cadaveric specimens injected with intravascular colored silicone to demonstrate the endoscopic anatomy of the PPF. This model could be used for surgical instruction of the transpterygoid approach. METHODS: We dissected six PPF in three cadaveric specimens prepared with intravascular injection of colored material using two different injection techniques. An endoscopic endonasal approach, including a wide nasoantral window and removal of the posterior antrum wall, provided access to the PPF. RESULTS: We produced our best anatomical model injecting colored silicone via the common carotid artery. We found that, using an endoscopic approach, a retrograde dissection of the sphenopalatine artery helped to identify the internal maxillary artery (IMA) and its branches. Neural structures were identified deeper to the vascular elements. Notable anatomical landmarks for the endoscopic surgeon are the vidian nerve and its canal that leads to the petrous portion of the internal carotid artery (ICA), and the foramen rotundum, and V2 that leads to Meckel's cave in the middle cranial fossa. These two nerves, vidian and V2, are separated by a pyramidal shaped bone and its apex marks the ICA. CONCLUSION: Our anatomical model provides the means to learn the endoscopic anatomy of the PPF and may be used for the simulation of surgical techniques. An endoscopic endonasal approach provides adequate exposure to all anatomical structures within the PPF. These structures may be used as landmarks to identify and control deeper neurovascular structures. The significance is that an anatomical model facilitates learning the surgical anatomy and the acquisition of surgical skills. A dissection superficial to the vascular structures preserves the neural elements. These nerves and their bony foramina, such as the vidian nerve and V2, are critical anatomical landmarks to identify and control the ICA at the skull base.     

腭鞘管、翼管与岩骨段颈内动脉的内镜手术应用解剖与进展

近年来,国外内镜下围绕着翼腭窝及颈内动脉区病变的内镜手术逐渐开展,对翼腭窝及其通道腭鞘管、翼管区的解剖研究亦不断深入。国内相关学者内镜下经鼻入路岩尖、颈内动脉区、斜坡及颅颈交界区解剖和临床应用解剖研究极少报道,究其原因,主要还是因为该区域重要解剖结构复杂而多变异,缺乏可以信赖的恒定的解剖标记,导致内镜颅底手术进展缓慢。内镜手术中,定向、定位障碍是耳鼻喉科医生和神经外科医生面临的最大风险^[1]。     

内镜下经眶外下壁入路颅底手术应用解剖研究初探

目的通过尸头解剖来探索经眶外下壁入路内镜手术所能达到的解剖通道、解剖标志及解剖方法等。方法对5具尸头（10侧）进行内镜下经眶外下壁入路颅底手术的细分解剖,通过逐步解剖来界定该入路所能达到解剖通道、颅内外重要解剖标志、解剖边界等。结果本研究界定了内镜下经眶外下壁入路颅底手术所能达到的5个通道,它们分别是三叉神经通道、破裂孔通道、海绵窦通道、岩锥及后颅窝通道、中颅窝通道,它们的边界、解剖标志、解剖通道、解剖步骤及方法都得以明确的界定。结论内镜下经眶外下壁入路颅底手术可以到达旁中线颅底、中颅窝,甚至是部分侧颅底及后颅窝,而且对于上颌神经、下颌神经颅内外段的暴露能提供很好的视野。当然,这还需要进一步的解剖研究及临床实践加以完善及检验。     

Endonasal endoscopic approach to the pterygopalatine and infratemporal fossae

The pterygopalatine fossa and infratemporal fossa are spaces located under the skull base, housing important neurovascular structures. Surgical access to these spaces is challenging because of their deep location and complex anatomy. Their surgical access has been classically carried out through multiple craniofacial approaches until the advent of endoscopic endonasal surgery at the end of the XX^th century. Our goal is to describe the transmaxillary-transsphenoidal-transpterygoid approach to the pterygopalatine and infratemporal fossae through endonasal endoscopic surgery based on anatomo-surgical dissection and an illustrative clinical case. We conclude that after careful radiologic evaluation of the feasibility of this technique, the endonasal endoscopic access to these spaces for tumor resection is efficient with reduced surgical morbidities. The endonasal approach is versatile and can be fashioned according to the nature and extent of the lesion.     

鼻内镜下经鼻翼突径路旁中线颅底手术

内镜颅底手术中选取合适的手术径路至关重要,视野暴露良好、避免重要血管神经损伤是两大原则,相对固定的解剖参考标志也是十分必要的。在内镜下经鼻腔入路旁中线颅底手术中,翼突根部、翼管、圆孔、卵圆孔、咽鼓管圆枕等解剖结构相对固定,可以互相作为参考。内镜经鼻翼突径路可以处理翼腭窝、颞下窝、海绵窦、Meckle腔、斜坡旁至海绵窦段颈内动脉、岩斜坡区域、岩尖区、咽鼓管区域、咽旁间隙上部。加强以翼突为解剖标志的内镜颅底手术,可以增加术中辨别的标志,并能以此为中心,向内、外扩展,充分利用其空间定位,增加术者在操作中的空间立体感,有助于内镜颅底手术的扩展。     

鼻内镜下经鼻径路解剖翼腭窝区临床观察

目的 研究鼻内镜下经鼻径路观察翼腭窝区的临床解剖特点, 以期为手术提供参考。方法 5例(10侧)成人尸头标本经乳胶灌注后, 在0°鼻内镜下分别经蝶腭孔和上颌窦后壁两种手术径路显露翼腭窝, 再开放蝶窦, 充分暴露视神经、颈内动脉及蝶窦外侧壁相关结构, 观察各解剖结构的三维立体关系。结果 不同手术径路显露翼腭窝的范围不同, 祛除上颌窦内侧壁后能最大程度显露翼腭窝内所有解剖结构, 开放蝶窦后能观察翼腭窝与蝶窦区域相关结构的解剖关系。结论 只要熟悉鼻内镜下翼腭窝及邻近区域的解剖结构及关系, 选择合适的病例, 鼻内镜下经鼻行翼腭窝区手术是安全可行的。     

鼻内镜下经鼻腔入路翼腭窝解剖学研究

目的：通过鼻内镜下鼻腔外侧壁入路对翼腭窝的解剖学研究,为临床内镜下翼腭窝手术入路提供解剖学基础。方法：10具新鲜尸头采用内镜下鼻腔外侧壁入路对翼腭窝进行解剖,观测手术径路中重要标志及穿经血管神经结构,并观测翼腭窝内结构及其与周围结构的关系。结果：①翼腭窝及其周围结构解剖关系复杂,颌内动脉及其分支变异较大;②蝶腭孔、眶下管、圆孔和翼管是翼腭窝重要骨性标志,同时翼腭窝可作为进入颞下窝和蝶窦的通路。结论：①熟知翼腭窝及其周围恒定的解剖标志可保持方向感,提高手术安全性;②鼻内镜下经鼻腔外侧壁入路可充分暴露翼腭窝,视野清晰,术中对重要神经血管控制较好,可根据病变范围变通手术径路;③经鼻内镜下鼻腔外侧壁入路可进入翼腭窝临近区域,处理临近区域病变。     

翼管在内镜经鼻颅底手术中的标志作用

目的通过影像学和解剖学方法进行研究以明确翼管在鼻内镜经鼻颅底手术中的价值并为临床提供参考。方法选23具尸头行冠状位及轴位高分辨CT扫描,观察翼管及其与周围结构的关系,并测量相关距离。选其中3具经过动脉灌注的尸头,分别采用经上颌窦、经鼻至翼腭窝-海绵窦入路进行鼻内镜下的解剖学研究。结果高分辨CT能够清晰显示翼管形态、走行及其与周围结构的关系。所有翼管均位于颈内动脉管水平段或其以下层面。鼻内镜解剖与相应的影像学提示相同,翼管内容恒定地指向颈内动脉前膝;翼管和圆孔之间的距离标定了一个手术门户。结论翼管是内镜经鼻颅底手术的一个重要解剖标志,作为骨性管道,高分辨CT可以清晰显示翼管。     

Vidian canal: analysis and relationship to the internal carotid artery

OBJECTIVES: The purpose of this study is to describe the anatomy and relationships of the vidian canal to known endonasal and skull base landmarks. This will allow the endoscopic skull base surgeon to safely approach the anterior genu of the petrous carotid artery during expanded endonasal approaches to the skull base. STUDY DESIGN: The study is a prospective cohort study. METHODS: Axial, coronal, and sagittal computed tomography scans of the paranasal sinuses and skull base of 44 patients were examined. Individuals with known skull base pathology were excluded. Measurements included the length of the vidian canal, the relationship of the vidian canal to the anterior genu of the petrous carotid artery, and the type of pneumatization of the sphenoid sinus as it pertains to foramen rotundum and the vidian canal. In addition, we will focus on the relationship of the vidian canal to the sphenopalatine foramen and base of the medial pterygoid plate. RESULTS: The degree of pneumatization of the sphenoid sinus is highly variable. The mean length of the vidian canal is 18 mm (10-23 mm). The vidian canal is found entirely within bone in 27% to 30% of scans reviewed. The anterior genu of the petrous internal carotid artery is found superior-medial to the vidian canal in 44 of 44 of the CT scans reviewed. The vidian canal runs medial to lateral in 93% to 98% of patients studied. CONCLUSIONS: As a result of this study the endoscopic skull base surgeon has a number of anatomical landmarks and measurements that may be helpful in safely localizing the anterior genu of the petrous internal carotid artery during expanded endonasal approaches to the skull base.     

Endonasal endoscopic approach to the petrous apex: an image-guided quantitative anatomical study.

BACKGROUND: The petrous apex is a relatively inaccessible region, deeply situated within the skull base. Removal of lesions from this area, traditionally accomplished via lateral approaches, can cause significant morbidity. We undertook an anatomical study to investigate the surgical anatomy of the petrous apex through an endonasal endoscopic approach, which has been sporadically described in the literature, to investigate its feasibility and to characterise clear and consistent surgical landmarks for access. METHODS: Cadaveric dissections were performed on five heads. Pre-dissection computed tomography scans were used, with the BrainLab navigation system, to verify entry into the petrous apex. Surgical landmarks were characterised in relation to fixed sphenoid sinus structures, and surgical access before and after drilling the sphenoid sinus rostrum was quantitatively compared. RESULTS: The landmark for entry into the petrous apex was the intersection of a vertical line halfway between the medial surface of the internal carotid artery and the midline, with a horizontal line one-third of the way up from the postero-inferior floor of the sphenoid sinus. The dimensions of the postero-superior sphenoid sinus were characterised by the inter-carotid distance, pituitary-to-sphenoid-floor distance and the width of the sphenoid sinus floor, which were 15 +/- 3 mm, 16 +/- 3 mm and 26 +/- 1.6 mm respectively. The surface area of surgical access was 193 +/- 28 mm(2), increasing to 316 +/- 39 mm(2) after drilling of the sphenoid rostrum (P < 0.001; paired t-test). CONCLUSIONS: Endoscopic approach to the petrous apex is anatomically feasible, and, aided by image navigation, could extend the scope of endonasal surgery to access highly-selected lesions in the middle cranial fossa.     

视神经管局部解剖与鼻内镜下解剖的结合研究

目的:为鼻内镜下视神经管减压术的临床运用提供解剖学依据。方法:10具(20侧)成人湿性尸头,从正中矢状位锯开,以直尺、量角器等测量工具测量视神经管与前鼻棘间的距离和角度;5具(10侧)(含儿童尸头2具)湿性尸头经鼻腔行鼻内镜下视神经管眶口至颅口段解剖,观察视神经管及其相关解剖标志。结果:大体标本观察,均可见到视神经管与颈内动脉呈“八”字形关系,测得视神经管内侧壁长度平均(9.12±1.89)mm,视神经管眶口直径平均(4.12±0.53)mm,前鼻棘到视神经管眶口内壁中点距离平均(61.22±6.23)mm,前鼻棘到视神经管眶口内壁中点的角度平均(45.3±4.5)°。鼻内镜下观察,沿视神经管眶口向后,可见到不同程度的一条反光带,即视神经管,7侧(70%)可见到明显的隆起,3侧(30%)无明显隆起,无法按照隆起形状判断视神经管。结论:结合大体解剖观察与鼻内镜下解剖观察,有助于准确识别鼻内镜下的视神经管,从而提高鼻内镜下视神经管手术的准确性。     

Endoscopic anatomy of the pterygopalatine fossa

BACKGROUND: The pterygopalatine fossa can be involved with a variety of infectious and neoplastic processes. This region can be entered endoscopically, but endoscopic landmarks to localize the neurovascular structures in the pterygopalatine fossa have not yet been reported. OBJECTIVES: The purpose of this study is to describe the location of the neurovascular structures in the pterygopalatine fossa in relation to consistent intranasal landmarks. METHODS: Endoscopic dissections of cadaveric heads were performed. The locations of neurovascular structures in the region were defined. RESULTS: The sphenopalatine foramen (SPF) served as the primary intranasal landmark to the pterygopalatine fossa (PPF). Mean distances from the SPF were measured with the following results: SPF to sphenopalatine ganglion (SPG), 4 mm medially and 6 mm laterally; SPF to foramen rotundum (FR), 7 mm; and SPF to vidian canal (VC), 2 mm. The internal maxillary artery followed an irregular and inconsistent course, making it difficult to define a reliable landmark for its location in the fossa. CONCLUSION: Entering the PPF inferior to the horizontal plane of the SPF along a vertical line drawn inferiorly from the infraorbital canal will avoid injury to the major neural structures in the fossa. Because of the inconsistent course and location of the internal maxillary artery, this structure may be at risk no matter where the fossa is entered. These landmarks will allow the surgeon to enter the PPF with more accuracy and less patient morbidity.     

翼腭窝和颞下窝三维影像学与经鼻内镜解剖学对照研究

目的 探讨多层螺旋CT(multislice spiral computed tomography,MSCT)测量翼腭窝和颞下窝解剖相关标志的方法及可行性.方法 对11具尸头行MSCT扫描,利用工作站确立解剖标志空间坐标,并计算解剖学数据.同时对11具尸头经鼻内镜解剖翼腭窝和颞下窝,并测量相关解剖学数据,对照影像学与鼻内镜下的共同解剖标志的形态,比较影像学和鼻内镜下解剖测量数据结果.结果 影像学方法和解剖学方法测量得到鼻小柱根部到蝶腭孔、翼管、圆孔、卵圆孔、棘孔、颈动脉管外口、破裂孔的距离((-x)±s,下同)分别为:(68.83±3.00)、(72.49±2.88)、(75.26±3.14)、(88.55±5.00)、(95.19±4.31)、(106.76±3.77)、(88.16±2.87)mm和(68.90±3.04)、(72.73±3.08)、(75.44±3.07)、(89.75±4.13)、(96.22±3.37)、(106.68±3.75)、(88.47±2.64)mm,两组数据差异无统计学意义(t值分别为-0.856、-1.134、-0.920、-1.923、-1.903、2.820、1.209,P值均>0.05).蝶腭孔、翼管、圆孔、卵圆孔、颈动脉管外口、破裂孔是鼻内镜解剖和影像学共同的解剖标志,可作为判断翼腭窝和颞下窝内神经、血管以及重要毗邻结构空间关系的解剖标志.结论 MSCT扫描三维重建测量翼腭窝和颞下窝相关标志解剖学数据可靠,可为临床个体化手术提供依据.     

Endoscopic orbital and optic nerve decompression

The endoscopic transnasal approach is well suited for decompression of both the orbit and optic canal. High-resolution nasal endoscopes provide excellent visualization for bone removal along the orbital apex and skull base. Endoscopic orbital decompression has proved to be safe and effective for the treatment of patients with Graves' orbitopathy; however, the indications and outcomes for endoscopic decompression of the optic nerve remain controversial.     

内镜下经鼻入路暴露岩尖的解剖研究

目的通过影像学、内镜手术两种方法对内镜下经鼻入路暴露岩尖这一手术入路进行研究,为临床应用提供依据。方法选取24具国人成人尸头标本,进行轴位、冠状位及矢状位高分辨率CT扫描,观察与内镜下经鼻入路暴露岩尖的相关解剖标志,并测量其距离。选择5例10%甲醛固定、动脉灌注染料的尸头标本,模拟内镜下经鼻入路暴露岩尖（10侧）。记录内镜下解剖图像,描述其相关解剖关系。结果通过影像学资料可了解蝶窦发育情况并测量一系列颅底骨性解剖标志的距离,蝶骨嵴至两侧视神经管眶口直线距离相比较无显著性差异（P〉0.05）。所有标本通过内镜经鼻入路均从颈内动脉内侧到达岩尖,翼管及翼管动脉可作为寻找颈内动脉的重要解剖标志。结论影像学资料应作为内镜下经鼻入路暴露岩尖手术的术前常规参考;蝶骨嵴位于两侧视神经管眶口的中点,为术中可靠的解剖标志。从解剖学角度内镜下经鼻入路暴露岩尖具有可行性,该入路径路短,副损伤小,可作为临床治疗岩尖病变的重要术式之一。     

Endoscopic endonasal anatomy of superior orbital fissure and orbital apex regions: critical considerations for clinical applications

The superior orbital fissure is a critical three-dimensional space connecting the middle cranial fossa and the orbit. From an endoscopic viewpoint, only the medial aspect has a clinical significance. It presents a critical relationship with the lateral sellar compartment, the pterygopalatine fossa and the middle cranial fossa. The connective tissue layers and neural and vascular structures of this region are described. The role of Muller’s muscle is confirmed, and the utility of the maxillary and optic strut is outlined. Muller’s muscle extends for the whole length of the inferior orbital fissure, passes over the maxillary strut and enters the superior orbital fissure, representing a critical surgical landmark. Dividing the tendon between the medial and inferior rectus muscle allows the identification of the main trunk of the oculomotor nerve, and a little laterally, it is usually possible to visualize the first part of the ophthalmic artery. Based on a better knowledge of anatomy, we trust that this area could be readily addressed in clinical situations requiring an extended approach in proximity of the orbital apex.     

不同内镜手术入路对翼腭窝及颞下窝的显露程度比较及其临床应用价值探讨

目的应用不同的内镜手术入路解剖翼腭窝及颞下窝,比较内镜下各手术入路的显露范围,为恰当选择内镜手术入路处理翼腭窝及颞下窝病变提供解剖学方面的依据。方法 4具8侧成人尸头标本,0°内镜引导下分别采取上颌窦后壁入路、扩大上颌窦后壁入路、鼻腔外侧壁入路、揭翻经上颌窦入路进行解剖学研究,观测各手术入路的有效显露范围。结果上颌窦后壁入路能显露翼腭窝上部和颞下窝内侧区深部;扩大上颌窦后壁入路在以上手术入路的基础上进一步显露翼腭窝下部;鼻腔外侧壁入路再进一步显露整个上颌窦和上颌窦底壁平面以上的颞下窝内外侧区;揭翻经上颌窦入路则能更进一步显露整个颞下窝。结论不同的内镜手术入路对翼腭窝及颞下窝的显露程度各不相同,以此为基础选择相应的手术入路处理不同范围的翼腭窝及颞下窝病变将有利于充分显露和有效切除病变,并尽可能避免不必要的手术损伤和并发症。     

经鼻内镜翼腭窝和颞下窝应用解剖学研究

目的探索经鼻内镜翼腭窝、颞下窝恒定的解剖标志,为手术处理该区域病变奠定基础。方法对11例尸头行鼻内镜侧颅底解剖学研究。经鼻内镜经中鼻道、蝶腭孔、上颌窦后壁入路,暴露翼腭窝及颞下窝的重要血管、神经及骨性解剖标志,并测量各解剖标志间的距离。结果经鼻内镜可恒定暴露蝶腭孔、翼管、圆孔、蝶腭神经节、眶下神经、卵圆孔、棘孔等重要侧颅底标志。鼻小柱基底到蝶腭孔、翼管、圆孔、卵圆孔、棘孔、破裂孔的距离分别为（69±3）、（73±3）、（75±3）、（90±5）、（96±4）、（88±3）mm。结论经鼻内镜可显露翼腭窝及颞下窝重要解剖结构,且各解剖结构可通过相互之间的距离及位置在鼻内镜二维平面上互相定位,以更直观、安全的处理该区域的病变。     

鼻内镜手术颌内动脉翼腭段的应用解剖

目的：研究颌内动脉翼腭段的走行及分支规律,为经鼻内镜手术过程中合理处理颌内动脉提供解剖学依据。方法：10具去脑颅底骨正中裂开,显微镜下解剖蝶腭动脉,经鼻内镜上颌窦入路开放翼腭窝,暴露颌内动脉翼腭段所有分支,将上颌窦后、内壁交界的凹陷定义为A点,通过眶下孔的水平线与上颌窦前壁、后外侧壁交线相交于B点,上颌窦前壁、后外侧壁和底壁的交点为D点,BD连线的中点为C点,颌内动脉翼腭段发出的第一分支点为C′点,观察其分支及走行规律。结果：蝶窦口下缘到鼻后中隔上动脉的距离为（5．88±2．21）mm;C′点位于AC上13侧,占65%（13／20）;位于AB上5侧,占25％（5／20）;位于AD上1侧,占5％（1／20）;高于AB1侧,占5％（1／20）。结论：熟悉颌内动脉的分支及走行对于治疗顽固性鼻出血和翼腭窝手术有重要意义;本实验中利用A、B、C、D点为参照点确定颌内动脉走行的方法,有助于内镜经鼻（上颌窦）手术中颌内动脉的定位及结扎处理。     

Endoscopic anatomy of the parasellar region

BACKGROUND: The aim of this study was to describe the endoscopic anatomy of the cavernous sinus and adjoining parasellar regions and their relationships to the sphenoid sinus. METHODS: An endoscopic transnasal transsphenoidal approach to the pituitary gland and posterior skull base was performed on three fresh frozen cadaver heads (six sides). Neural and vascular anatomic landmarks of the cavernous sinus and parasellar regions were identified and correlated with sphenoid surface anatomy. RESULTS: The posterior wall of the sphenoid sinus presents several surface landmarks allowing the identification of the sella, carotid artery, and optic nerve. Identification of the optic-carotid recess allows reflection of the internal carotid artery medially and access to the cavernous sinus. Further lateral dissection allows for easy identification of the oculomotor, trochlear, trigeminal, and abducens nerves. The ophthalmic artery then can be followed from its origin on the internal carotid artery coursing anteriorly into the orbit. The optic chiasm also can be easily identified superiorly. Posteriorly, careful dissection allows access to the basilar artery along the clivus. CONCLUSION: As endoscopic surgeons continue to expand their procedures to involve areas of the skull base outside the paranasal sinuses, knowledge of the endoscopic anatomy of the sella, parasellar, and adjacent areas is paramount. Critical landmarks are readily evident in the sphenoid sinus providing good access to neural and vascular structures of this region of the skull base.