Endoscopic endonasal transpterygoid approaches: Anatomical landmarks for planning the surgical corridor (original) (raw)
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E XPANDED endoscopic surgery is a standard option in the armamentarium for skull base approaches to address numerous pathologies. 2,4,13,16,27 Technical improvements over the past decade have made endoscopy a viable alternative to conventional microscopic or open procedures. 10,31 Expanded endoscopic endonasal approaches have been used to access lesions in the clivus, 17,20 posterior fossa, 18,29 craniovertebral junction, 5,24 and anterior fossa. 29 One such expanded endoscopic approach, the endoscopic transmaxillary approach (ETMA), is used to access le-sions within the maxillary sinus, lateral sphenoid sinus, cavernous sinus, and anterolateral skull base. 1,8,14,23,25,32,34 The transmaxillary corridor is most commonly accessed through an endonasal approach and a medial maxillec-tomy or through a sublabial incision and a direct anterior maxillectomy (i.e., Caldwell-Luc approach). 8,23,25 Endoscopic approaches to the anterolateral skull base are challenging for neurosurgeons because of the unfamil-abbreviations ETMA = endoscopic transmaxillary approach; ICA = internal carotid artery; IOA = infraorbital artery; ION = infraorbital nerve. obJective Endoscopic transmaxillary approaches (ETMAs) address pathology of the anterolateral skull base, including the cavernous sinus, pterygopalatine fossa, and infratemporal fossa. This anatomically complex region contains branches of the trigeminal nerve and external carotid artery and is in proximity to the internal carotid artery. The authors postulated, on the basis of intraoperative observations, that the infraorbital nerve (ION) is a useful surgical landmark for navigating this region; therefore, they studied the anatomy of the ION and its relationships to critical neurovascular structures and the maxillary nerve (V2) encountered in ETMAs. methods Endoscopic anatomical dissections were performed bilaterally in 5 silicone-injected, formalin-fixed cadav-eric heads (10 sides). Endonasal transmaxillary and direct transmaxillary (Caldwell-Luc) approaches were performed, and anatomical correlations were analyzed and documented. Stereotactic imaging of each specimen was performed to correlate landmarks and enable precise measurement of each segment. results The ION was readily identified in the roof of the maxillary sinus at the beginning of the surgical procedure in all specimens. Anatomical dissections of the ION and the maxillary branch of the trigeminal nerve (V2) to the cavernous sinus suggested that the ION/V2 complex has 4 distinct segments that may have implications in endoscopic approaches: 1) Segment I, the cutaneous segment of the ION and its terminal branches (5-11 branches) to the face, distal to the in-fraorbital foramen; 2) Segment II, the orbitomaxillary segment of the ION within the infraorbital canal from the infraorbital foramen along the infraorbital groove (length 12 ± 3.2 mm); 3) Segment III, the pterygopalatine segment within the ptery-gopalatine fossa, which starts at the infraorbital groove to the foramen rotundum (13 ± 2.5 mm); and 4) Segment IV, the cavernous segment from the foramen rotundum to the trigeminal ganglion (15 ± 4.1 mm), which passes in the lateral wall of the cavernous sinus. The relationship of the ION/V2 complex to the contents of the cavernous sinus, carotid artery, and pterygopalatine fossa is described in the text. conclusions The ION/V2 complex is an easily identifiable and potentially useful surgical landmark to the foramen rotundum, cavernous sinus, carotid artery, pterygopalatine fossa, and anterolateral skull base during ETMAs.
Journal of Neurosurgery, 2007
Object The pterygopalatine fossa is an area that lies deep within the skull base. The recent extensive use of the endoscopic endonasal approach has provided neurosurgeons with a method to reach various areas of the skull base through a less invasive approach than traditional transcranial or transfacial approaches. This study aims to provide neurosurgeons with new data concerning direct endoscopic measurements and precise anatomical topography features of the pterygopalatine fossa. Methods An anatomical dissection of six fixed cadaver heads (12 pterygopalatine fossae) was performed to analyze spatial relationships and distances between the most important neurovascular structures in this region, and to estimate the size of the endoscopic surgical field for operations in this area. The endoscopic endonasal approach offers direct access to the pterygopalatine fossa through its anteromedial walls. Conclusions Using an endoscopic endonasal approach makes it possible to identify all of the...
The Laryngoscope, 2008
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.
Anatomy based corridors to the infratemporal fossa: Implications for endoscopic approaches
Head & Neck, 2019
BackgroundThe infratemporal fossa (ITF) represents an area densely packed with neurovascular structures within irregular boundaries. The goal of this study was to classify the ITF into zones corresponding to its anatomical spaces and the order in which they are encountered during an endonasal approach (anteroposterior axis).MethodsSix cadaveric specimens (12 sides) with injected colored latex were dissected. Following an endoscopic medial maxillectomy and Denker's approach, a progressive exploration of the masticator space and upper parapharyngeal space was completed. A classification of the ITF based on well‐defined spaces was ascertained.ResultsThe ITF was divided into five zones: Zone 1 (retromaxillary space)—space lying between the posterolateral wall of the maxillary sinus and the temporalis and pterygoid muscles. Zone 2 (superior interpterygoid space)—area including the superior head of the lateral pterygoid muscle, V3, and foramen ovale. Zone 3 (inferior interpterygoid sp...
Extended endoscopic endonasal approach to the pterygopalatine fossa: anatomic study
Journal of Neurosurgical Sciences, 2009
Our aim in this study was to recognize the endoscopic anatomy of the pterygopalatine fossa (PPF) and the anatomic variations of the related neurovascular structures, to define the endoscopic endonasal approach to this region. Six fresh adult cadavers were studied (N=6) by endoscopic endonasal approach. To reach the pterygopalatine fossa endonasally, we performed the middle meatus transpalatine approach in 2 cadavers, the middle meatus transnasal approach in 2 cadavers and the inferior turbinatectomy transnasal approach in 2 cadavers. The superior and posterior walls of the maxillary sinus were defined and studied. The sphenopalatine foramen is widened by drilling the orbital process of the foramen and the sphenopalatine artery was exposed. The posterior wall of maxillary sinus was opened to expose the pterygopalatine fossa and its neurovascular contents, which were studied and documented. The PPF was easily approached by endoscopic transnasal transmaxillary approach. The PPF region was best exposed by the middle meatus tranasal approach. In the PPF; infraorbital nerve, vidian nerve, major palatine nerve, the infraorbital artery, internal maxillary artery, sphenopalatine artery, descending palatine artery, posterior superior alveolar artery and buccal artery were exposed. According Morton and Khan morphologic classification of the third portion of the internal maxillary artery we found intermediate type in 2 cadavers (33.3%), M' type in 2 cadavers (33.3%), T' type in 1 cadaver (16.7%) and Y' type in 1 cadaver (16.7%). Also, according to Chio and Park classification of the branching type of the infraorbital artery, posterior superior alveolar artery and deep palatine artery, we found type I in 4 cadavers (66%) and type II in 2 cadavers (33%). During the endoscopic transnasal transmaxillary approach to the PPF, it is possible to face wide range of variations in every phase of the approach. Understanding the anatomy of this region and the neurovascular relations from the endoscopic view by cadaver dissections will help us to performed more controlled and safe surgery.
Journal of Neurosurgery, 2021
OBJECTIVE The anteromedial triangle (AMT) is the triangle formed by the ophthalmic (V1) and maxillary (V2) nerves. Opening of this bony space offers a limited access to the sphenoid sinus (SphS). This study aims to demonstrate the utility of the orbitopterygopalatine corridor (OPC), obtained by enlarging the AMT and transposing the contents of the pterygopalatine fossa (PPF) and V2, as an entrance to the SphS, maxillary sinus (MaxS), and nasal cavity. METHODS Five formalin-injected cadaveric specimens were used for this study (10 approaches). A classic pterional approach was performed. An OPC was created through the inferior orbital fissure, between the orbit and the PPF, by transposing the PPF inferiorly. The extent of the OPC was measured using neuronavigation and manual measurements. Two illustrative cases using the OPC to access skull base tumors are presented in the body of the article. RESULTS Via the OPC, the SphS, MaxS, ethmoid sinus (EthS), and nasal cavity could be accesse...
The anatomy of the pterygopalatine fossa keeps a traditional level and is viewed as constant, even though a series of structures neighboring the fossa are known to present individual variations. We aimed to evaluate on 3D volume renderizations the anatomical variables of the pterygopalatine fossa, as related to the variable pneumati-zation patterns of the bones surrounding the fossa. The study was performed retrospectively on cone beam computed tomography (CBCT) scans of 100 patients. The pterygopalatine fossa was divided into an upper (orbital) and a lower (pterygomaxillary) floor; the medial compartment of the orbital floor lodges the pterygopalatine gan-glion. The pneumatization patterns of the pterygopalatine fossa orbital floor walls were variable: (a) the posterior wall pneumatization pattern was determined in 89.5 % by recesses of the sphenoidal sinus related to the maxillary nerve and pterygoid canals; (b) the upper continuation of the pterygopalatine fossa with the orbital apex was narrowed in 79.5 % by ethmoid air cells and/or a maxillary recess of the sphenoidal sinus; (c) according to its pneu-matization pattern, the anterior wall of the pterygopalatine fossa was a maxillary (40.5 %), maxillo-ethmoidal (46.5 %), or maxillo-sphenoidal (13 %) wall. The logistic regression models showed that the maxillo-ethmoidal type of pterygopalatine fossa anterior wall was significantly associated with a sphenoidal sinus only expanded above the pterygoid canal and a spheno-ethmoidal upper wall. The pterygopalatine fossa viewed as an intersinus space is related to variable pneumatization patterns which can be accurately identified by CBCT and 3DVR studies, for anatomic and preoperatory purposes.
Journal of Neurological Surgery Part B: Skull Base, 2012
ABSTRACT Objective: Surgical treatment of posterior fossa lesions is challenging. Traditional transcranial approaches have been recently complemented with variants of the endoscopic endonasal route. However, a qualitative and quantitative study about their indications is lacking in the literature. The main aim of the present study was to analyze and compare the surgical anatomy pertinent to the dorsal transcranial transcondylar “far lateral approach” (TC-FLA) to that of the ventral endoscopic endonasal transcondylar “far medial approach” (EE-FMA) route. In addition, we propose a classification of the posterior fossa and provide surgical recommendations based on its boundaries. Methods: Eight cadaveric specimens were dissected and analyzed bilaterally. We measured the degree of brainstem exposure and the dimensions of the surgical corridor. Three clinical scenarios are described to complement the anatomic study and to illustrate the clinical feasibility of the proposed surgical strategies. Results: The hypoglossal nerve, vertebral artery, and hypoglossal canal divide the lower third of the clivus into ventromedial (VMC) and dorsolateral (DLC) compartments. These boundaries define the surgical indications of the studied approaches. The endoscopic endonasal far medial approach provides a significantly larger exposure of the VMC brainstem (464.6 ± 68.34 mm2) than the far lateral approach (126.35 ± 32.25 mm2) P < 0.01. The transcranial exposure to the DLC measured 295.24 ± 58.03 mm2 (74% of the total DLC). The DLC exposure was not possible using the endonasal route. A suitable surgical corridor between the two compartments was observed in 75% of specimens. The spinal root of the accessory nerve divided this corridor in 44% of specimens. The surgical corridor for the far lateral approach was significantly larger (78.19 ± 14.54 mm2) than that of the endoscopic endonasal far medial approach (23.77 ± 15.17 mm2), P = 0.03. When accessed through a far medial approach, the surgical corridor was obstructed by the cerebellar hemisphere, which prevented DLC dissection, whereas the cerebellar hemisphere was retracted laterally during the far lateral approach allowing dissection of the ventromedial compartment. Conclusions: The ventral approach (EE-FMA) offers a safe, wide exposure of the lower third of the clivus for lesions that expand ventromedially to the hypoglossal nerve. The dorsal (TC-FLA) is most suitable for lesions located dorsolateral to the lower cranial nerves. The VA and hypoglossal canals are the most important landmarks to guide the surgical planning. A combined ventral-dorsal approach should be considered for resection of extensive lesions involving both the ventromedial and dorsolateral compartments.
Neurosurgical …, 2005
Object. The middle third of the clivus and the region around the petrous internal carotid artery (ICA) is a difficult area of the skull base in terms of access. This is a deep area rich with critical neurovascular structures, which is often host to typical skull base diseases. Expanded endoscopic endonasal approaches offer a potential option for accessing this difficult region. The objective of this paper was to establish the clinical feasibility of gaining access to the paraclival space in the region of the middle third of the clivus, to provide a practical modular and clinically applicable classification, and to describe the relevant critical surgical anatomy for each module. Methods. The anatomical organization of the region around the petrous ICA, cavernous sinus, and middle clivus is presented, with approaches divided into zones. In an accompanying paper in this issue by Cavallo, et al., the anatomy of the pterygopalatine fossa is presented; this was observed through cadaveric dissection for which an expanded endonasal approach was used. In the current paper the authors translate the aforementioned anatomical study to provide a clinically applicable categorization of the endonasal approach to the region around the petrous ICA. A series of zones inferior and superior to the petrous ICA are described, with an illustrative case presented for each region. Conclusions. The expanded endonasal approach is a feasible approach to the middle third of the clivus, petrous ICA, cavernous sinus, and medial infratemporal fossa in cases in which the lesion is located centrally, with neurovascular structures displaced laterally.