Endoscopic Resection of Pterygopalatine Fossa and Infratemporal Fossa Malignancies

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal and Endoscopic-Assisted Transmaxillary Transpterygoid Approaches

Introduction  The endoscopic endonasal transpterygoid approach (EETPA) with or without the addition of the endoscopic-assisted sublabial anterior transmaxillary approach (ESTA) has become increasingly utilized for lesions posterior to the pterygopalatine fossa (PPF), including infratemporal fossa (ITF), lateral recess of the sphenoid sinus, Meckel's cave, petrous apex, and parapharyngeal space. The main goal of this study is to develop an educational resource to learn the steps of the EETPA for trainees. Methods  EETPA and ESTA were performed in 12 specimens by neurosurgery trainees, under supervision from the senior authors. One EETPA and one ESTA were performed on each specimen on opposite sides. Dissections were supplemented with representative cases. Results  After a wide unilateral sphenoidotomy, ethmoidectomy, and partial medial maxillectomy, the anteromedial bone limits of the PPF were identified and drilled out. The pterygoid progress was modularly removed. By enlarging the opening of the posterior and lateral walls of the maxillary sinus through EETPA and ESTA, respectively, the neurovascular and muscular compartments of the PPF and ITF were better identified. The EETPA opens direct corridors to the PPF, medial ITF, middle cranial fossa, cavernous sinus, Meckel's cave, petrous apex, and internal carotid artery. If a more lateral exposure of the ITF is needed, the ESTA is an appropriate addition. Conclusion  Despite the steep learning curve of the EETPA, granular knowledge of its surgical anatomy and basic surgical steps are vital for those advancing their learning in complex endoscopic approaches to the ventral skull base when expanding the approach laterally in the coronal plane.

Endoscopic endonasal transpterygoid nasopharyngectomy: Anatomical considerations and technical note

BACKGROUND

The study was designed to identify new landmarks in the parapharyngeal segment of the internal carotid artery (ICA) for nasopharyngectomy and describe a surgical procedure of endoscopic endonasal transpterygoid nasopharyngectomy (EETPN).

METHODS

Four cadaveric specimens were injected with colored silicone and subjected to CT scanning before dissection. The nasopharyngeal skull base was exposed using the endoscopic endonasal transpterygoid approach. The clinical data of four patients with nasopharyngeal malignances who underwent EETPN were reviewed.

RESULTS

The lateral edge of the longus capitis muscle medially; the foramen lacerum, petrous apex spine and the stump of the levator veli palatini muscle superior laterally; and the upper parapharyngeal ICA laterally constitute the ICA-longus capitis muscle-petrous apex spine triangle which was a novel landmark for the upper parapharyngeal segment of the ICA.

CONCLUSION

The ICA-longus capitis muscle-petrous apex spine triangle are important landmarks of the upper parapharyngeal segment of the ICA.

Endoscopic-assisted en-bloc pterygomaxillectomy: Identifying an efficient and safe location for the pterygoid osteotomy

BACKGROUND

For aggressive maxillary sinus and pterygopalatine fossa (PPF) tumors, an en-bloc pterygomaxillectomy may be indicated.

METHODS

Five head specimens were used to study the feasibility of an en-bloc pterygomaxillectomy. Eighty-five non-pathological CT scans were used to compare the superior edge of the inferior turbinate (IT) and the middle turbinate tail (MT) as landmarks for the pterygoid osteotomy.

RESULTS

Through a combined sublabial-subperiosteal incision and transoral route, a mid-sagittal osteotomy through the hard palate and an axial osteotomy below the infraorbital foramen were performed. For the endoscopic pterygoid osteotomy, an infra-vidian transpterygoid approach was performed, subsequently removing the pterygomaxillectomy en-bloc. As landmarks, the osteotomies at the level of the MT tail and IT resected the pterygoid plates completely, but the IT osteotomy was further away from the vidian canal (7.5 vs. 6 mm).

CONCLUSIONS

The endoscopic-assisted en-bloc pterygomaxillectomy is feasible. The IT landmark is safe and ensures complete resection of the pterygoid plates.

Endoscopic multiport resection of a transspatial, retromaxillary tumor

Tumors of the retromaxillary tissues can grow to involve multiple deep, skull base spaces, including the pterygopalatine fossa, infratemporal fossa, and the parapharyngeal space. Management of these tumors must account for heterogeneous pathology as well as the critical neurovasculature in and surrounding these spaces. Traditionally, these tumors have been approached the open skull base or anterior craniofacial approaches. Modern endoscopic endonasal and multiport approaches have increasingly become favored for certain tumors in the retromaxillary skull base region. In this report, we present the case of a 42-year-old male presented with refractory headache and was found to have a left-sided 5.0 cm tumor of the retromaxillary spaces with widening of foramen ovale. Differential diagnosis included schwannoma of the mandibular nerve, paraganglioma, salivary gland tumor, or soft tissue tumor. The tumor was approached via an expanded endoscopic approach to the pterygopalatine fossa and augmented with a Caldwell-Luc maxillotomy, to access the posterolateral extent of the tumor. A 2-surgeon team utilized visualization and instrumentation through both the transnasal and transmaxillotomy corridors to completely mobilize and remove the tumor. Post-resection imaging demonstrated complete removal of the tumor and pathology confirmed the diagnosis of schwannoma. Custom, multiport surgery can be a safe, less invasive approach for successful management of well selected retromaxillary skull base tumors.

Tumors Involving the Infratemporal Fossa: A Systematic Review of Clinical Characteristics and Treatment Outcomes

BACKGROUND

Infratemporal fossa (ITF) tumors represent various pathologies and are seldom described in the literature, reflecting their rarity. Here we review the literature on tumors invading ITF and describe patient characteristics, treatment strategies, and clinical outcomes.

METHODS

Relevant articles were retrieved from PubMed, Scopus, and Cochrane. A systematic review and meta-analysis were conducted on the clinical presentation, treatment protocols, and clinical outcomes.

RESULT

A total of 27 articles containing 106 patients with ITF tumors (median tumor size: 24.3 cm³ [interquartile range, 15.2-42 cm³]) were included (median age: 46 years [interquartile range, 32-55 years]; 59.4% were males]). Of the confirmed tumor pathology data, schwannomas (n = 24; 26.1%) and meningiomas (n = 13; 14.1%) were the most common tumors. Facial hypoesthesia (n = 22; 18.5%), auricular/preauricular pain (n = 20; 16.8%), and headaches (n = 11; 9.2%) were the most common presenting symptoms. Of patients who had surgical resection (n = 97; 95.1%), 70 (73.7%) had transcranial surgery (TCS) and 25 (26.3%) had endoscopic endonasal surgery (EES). Among available details on the extent of resection (n = 84), gross-total resection (GTR) was achieved in 62 (73.8%), and 5 (6.0%) had biopsy only. Thirty-five (33.0%) patients had postoperative complications. Among cases with available data on reconstruction techniques (n = 8), four (50%) had adipofascial antero-lateral thigh flap, three (37.5%) had latissimus dorsi free flap, and one (12.5%) had antero-lateral thigh flap. Fourteen (13.2%) patients had adjuvant chemotherapy, and sixteen (15.1%) had adjuvant radiotherapy. During a median follow-up time of 28 months (IQR, 12.25-45.75 months), 15 (14.2%) patients had recurrences, and 18 (17.0%) patients died. The median overall survival (OS) time was 36 months (95% confidence interval: 29-41 months), and the 5-year progression-free survival (PFS) rate was 61%.

CONCLUSION

Various tumor types with different biological characteristics invade the ITF. The present study describes patient demographics, clinical presentation, management, and outcomes. Depending on the tumor type and patient condition, patient-tailored management is recommended to optimize treatment outcomes.

Greater Palatine Canal: Computed Tomography-Based Anatomic Analysis And Clinical Significance for the Sinus and Skull Base Surgeon

OBJECTIVE

Our aim is to describe the location and course of the greater palatine canal (GPC) by analyzing its relationship with anatomical landmarks that can be used during endoscopic sinus surgery. This information might help prevent injury to the neurovascular bundle.

METHODS

A retrospective evaluation of paranasal sinus CT scans of 100 consecutive random patients, 200 sides, was performed. Five measurements related to the course of the GPC were conducted, from cranial to caudal. The anatomical landmarks were the inferior bony border of the sphenopalatine foramen to the cranial entrance of the GPC, the distance from the most dorsal, and inferior bony insertion of the middle turbinate and the inferior turbinate bones to the anterior margin of the GPC. The angle between the horizontal palatine bone and the GPC, its length, and the prevalence of osteophytes in GPC was also assessed.

RESULTS

The mean distance of the inferior border of the sphenopalatine foramen to the cranial entrance of the GPC was 9.39 ± 1.72 mm. The mean distance of the dorsal insertion of the middle turbinate to the anterior margin of the GPC was 3.89 ± 0.93 mm. The distance of the dorsal insertion of the inferior turbinate to the anterior margin of the GPC was 3.16 ± 0.81 mm. The mean angle between the horizontal palatine bone and the GPC was 114.33 ± 10.92º and the mean length of the GPC was 30.23 ± 3.74 mm. None of the measurements showed a significant difference between the two sides.

CONCLUSIONS

The landmarks used are easy to locate and assess on CT scans. These findings may help to make dissection safer in pathologies related to the pterygopalatine fossa, lateral sphenoid sinus or adjacent skull base.

Endonasal access to the lateral poststyloid space: Far lateral extension of an endoscopic endonasal corridor

The styloid process constitutes the posterolateral boundary for an endonasal exposure of the infratemporal fossa. This study aims to explore the feasibility of a far-lateral extension to the lateral poststyloid space via an endonasal corridor. An endonasal dissection was performed on six cadaveric specimens (12 sides). Following an endoscopic endonasal access to the parapharyngeal space, the styloid process and the tympanic portion of the temporal bone were removed to reveal the jugular bulb and the extratemporal facial nerve. Distances from the anterior nasal spine to the relevant landmarks were measured using a surgical navigation device. Through an endonasal corridor, only the anteroinferior aspect of the jugular bulb was exposed. Conversely, the extratemporal facial nerve could be sufficiently exposed, and the deep temporal nerve could be transposed to the stylomastoid foramen. The average horizontal distances from the nasal spine to the posterior tract of V₃ , styloid process, and facial nerve were 79.33 ± 3.41, 97.10 ± 4.74, and 104.77 ± 4.42 mm, respectively. Access to the lateral poststyloid space via an endonasal corridor is feasible, potentially providing an alternative approach to address select lesions extending to this region. The deep temporal nerve has a similar diameter to that of the facial nerve; thus, providing potential reinnervation of the facial nerve.

Infra-Temporal and Pterygo-Palatine Fossae Tumors: A Frontier in Endoscopic Endonasal Surgery—Description of the Surgical Anatomy of the Approach and Report of Illustrative Cases

Infratemporal and pterygopalatine fossae (ITF and PPF) represent two complex paramedian skull base areas, which can be defined as jewelry boxes, containing a large number of neurovascular and osteomuscular structures of primary importance. They are in close communication with many craniofacial areas, such as nasal/paranasal sinuses, orbit, middle cranial fossa, and oral cavities. Therefore, they can be involved by tumoral, infective or inflammatory lesions spreading from these spaces. Moreover, they can be the primary site of the development of some primitive tumors. For the deep-seated location of ITF and PPF lesions and their close relationship with the surrounding functional neuro-vascular structures, their surgery represents a challenge. In the last decades, the introduction of the endoscope in skull base surgery has favored the development of an innovative anterior endonasal approach for ITF and PPF tumors: the transmaxillary-pterygoid, which gives a direct and straightforward route for these areas. It has demonstrated that it is effective and safe for the treatment of a large number of benign and malignant neoplasms, located in these fossae, avoiding extensive bone drilling, soft tissue demolition, possibly unaesthetic scars, and reducing the risk of neurological deficits. However, some limits, especially for vascular tumors or lesions with lateral extension, are still present. Based on the experience of our multidisciplinary team, we present our operative technique, surgical indications, and pre- and post-operative management protocol for patients with ITF and PPF tumors.

Endoscopic Endonasal Approach to the Pterygopalatine Fossa and Infratemporal Fossa: Comparison of the Prelacrimal and Denker's Corridors

BACKGROUND

Both the endoscopic transnasal Denker's and prelacrimal approaches provide surgical access to the pterygopalatine fossa (PPF) and infratemporal fossa (ITF).

OBJECTIVES

This study compares the potential maximum exposure of the PPF and ITF and quantifies the difference in surgical freedom via endoscopic Denker's and prelacrimal approaches.

METHODS

Six cadaveric specimens (12 sides) were dissected using a prelacrimal approach on one side and an endoscopic Denker's approach on the contralateral side. The contents of the PPF and ITF were sequentially exposed. Surgical freedom for each corridor was subsequently calculated.

RESULTS

This study confirms that both the prelacrimal and Denker's approaches provide adequate exposure of the PPF and ITF. The maximum exposure boundaries were similar for both approaches, including the middle cranial fossa superiorly, floor of the maxillary sinus inferiorly, zygomatic arch and temporomandibular joint laterally, and post-styloid space posteriorly. However, the data revealed a statistically significant difference (p < 0.05) regarding the surgical freedom of the prelacrimal (388.17 ± 32.86 mm²) and the endoscopic Denker's approaches (906.35 ± 38.38 mm²).

CONCLUSION

When compared with an endoscopic Denker's approach, a prelacrimal approach seems to achieve a similar extent of exposure (ie, visualization) of the PPF and ITF. Nonetheless, the endoscopic Denker's approach offers superior surgical freedom; thus, it is preferred for the management of complex lesions which requires increased instrument maneuverability with a 3- or 4-handed technique.

Middle cranial fossa trigeminal schwannoma resection through endoscopic transnasal maxillary sinus approach: A case report and literature review

The endoscopic transnasal maxillary sinus approach is usually performed in resecting tumors located in the pterygopalatine fossa and infratemporal fossa, but is rarely used in the resection of lesions in the middle cranial fossa. Because of the complicated anatomical structure of the middle cranial fossa, trigeminal schwannomas (TSs) located in this region are usually dissected through conventional craniotomy surgical approaches; however, the endoscopic transnasal maxillary sinus approach can be used in resection of middle cranial fossa TSs. The current study presented the case of a 59-year-old man who suffered intermittent headaches for 2 years without other notable medical history and neurological abnormalities. The patient was diagnosed with a middle cranial fossa TS. After imaging and assessment of anatomical features, the tumor was totally resected through the transnasal maxillary sinus approach. Following surgery, the symptoms were relieved and the patient returned to a normal life. Light numbness was complained of in the distribution area of the maxillary nerve of the right side of the face, but this was gradually relieved. Combined with a literature review, the present case indicated that the endoscopic transnasal maxillary sinus approach may provide a safer and more direct option for resecting middle cranial fossa lesions, which is worthy of increased clinical application.

Anatomical Variations and Relationships of the Infratemporal Fossa: Foundation of a Novel Endonasal Approach to the Foramen Ovale

Objective  Access to the infratemporal fossa (ITF) is complicated by its complex neurovascular relationships. In addition, copious bleeding from the pterygoid plexus adds to surgical challenge. This study aims to detail the anatomical relationships among the internal maxillary artery (IMA), pterygoid plexus, V _3, and pterygoid muscles in ITF. Furthermore, it introduces a novel approach that displaces the lateral pterygoid plate (LPP) to access the foramen ovale. Design and Main Outcome Measures  Six cadaveric specimens (12 sides) were dissected using an endonasal approach to the ITF modified by releasing and displacing the LPP and lateral pterygoid muscle (LPTM) as a unit. Subperiosteal elevation of the superior head of LPTM revealed the foramen ovale. The anatomic relationships among the V ₃ , pterygoid muscles, pterygoid plexus, and IMA were surveyed. Results  In 9/12 sides (75%), the proximal IMA ran between the temporalis and the LPTM, whereas in 3/12 sides (25%), the IMA pierced the LPTM. The deep temporal nerve was a consistent landmark to separate the superior and inferior heads of LPTM. An endonasal approach displacing the LPP in combination with a subperiosteal elevation of the superior head of LPTM provided access to the posterior trunk of V ₃ and foramen ovale while sparing injury of the LPTM and exposing the pterygoid plexus. The anterior trunk of V ₃ traveled anterolaterally along the greater wing of sphenoid in all specimens. Conclusion  Displacement of the LPP and LPTM provided direct exposure of foramen ovale and V ₃ avoiding dissection of the muscle and pterygoid plexus; thus, this maneuver may prevent intraoperative bleeding and postoperative trismus.

An Endoscopic Endonasal Nasopharyngectomy with Posterolateral Extension

Background Invasion depth influences the choice for extirpation of nasopharyngeal malignancies. This study aims to validate the feasibility of endoscopic endonasal resection of lesions with a posterolateral invasion. As a secondary goal, the study intends to propose a classification system of endoscopic endonasal nasopharyngectomy determined by the depth of posterolateral invasion.

Methods Eight cadaveric specimens (16 sides) underwent progressive nasopharyngectomy using an endoscopic endonasal approach. Resection of the torus tubarius, Eustachian tube (ET), medial pterygoid plate and muscle, lateral nasal wall, and lateral pterygoid plate and muscle were sequentially performed to expose the fossa of Rosenmüller, petroclival region, parapharyngeal space (PPS), and jugular foramen, respectively.

Results Technical feasibility of endonasal nasopharyngectomy toward a posterolateral direction was validated in all 16 sides. Nasopharyngectomy was classified into four types as follows: (1) type 1: resection restricted to the posterior or superior nasopharynx; (2) type 2: resection includes the torus tubarius which is suitable for lesions extended into the petroclival region; (3) type 3: resection includes the distal cartilaginous ET, medial pterygoid plate, and muscle, often required for lesions extending laterally into the PPS; And (4) type 4: resection includes the lateral nasal wall, pterygoid plates and muscles, and all the cartilaginous ET. This extensive resection is required for lesions involving the carotid artery or extending to the jugular foramen region.

Conclusion Selected lesions with posterolateral invasion into the PPS or jugular foramen is amenable to a resection via expanded endonasal approach. Classification of nasopharyngectomy based on tumor depth of posterolateral invasion helps to plan a surgical approach.

A novel landmark for endonasal surgery of the pterygopalatine fossa and inferior orbital fissure: The orbito-pterygo-sphenoidal ligament

The pterygopalatine fossa contains a dense and complex array of neurovascular structures vulnerable to accidental surgical injury. This study aims to describe a novel landmark, the orbito-pterygo-sphenoidal ligament (OPSL), and implications of this structure for surgery in the pterygopalatine fossa and the inferior orbital fissure. Six cadaveric specimens (12 sides) were dissected using an endonasal approach to expose the periosteal layers associated with the pterygopalatine fossa and orbit. The thickened triangular-shaped ligament at their confluence was termed the OPSL. Dimensions of its lateral, inferior, and medial borders were measured, and their anatomical relationships defined. The pterygopalatine ganglion and the maxillary nerve lie immediately inferior and deep into the OPSL. The superior aspect of the posterior nasoseptal artery and nerve are covered by the medial OPSL. The lateral and inferior borders of the OPSL are contiguous with the periorbita and the periosteum of the pterygopalatine fossa, respectively. Along the medial border of the ligament, the openings of the palatovaginal fissure, vidian canal, and foramen rotundum were sequentially identified in a medial to lateral trajectory. The length of the lateral, inferior, and medial borders of the triangular OPSL were 13.25 ± 0.62, 14.25 ± 0.45, and 12.08 ± 0.90 mm, respectively. The OPSL is a thick, triangular-shaped fascial confluence, which may serve as a landmark for procedures within the pterygopalatine fossa and the inferior orbital fissure.

Endoscopic Endonasal Management of Pterygopalatine Fossa Tumors

ABSTRACT

Surgical removal of pterygopalatine fossa (PPF) tumors with endoscopic endonasal approach is still challenging. The present study aimed to evaluate our endoscopic endonasal management of PPF tumors based on the tumor pathology and purpose of the surgery. This comprised both a single nostril approach for biopsy and a binostril approach for complete resection of benign and noninfiltrating tumors. Based on this strategy, 12 patients underwent endoscopic endonasal surgery for PPF tumors between 2013 and 2018. The patients' data were analyzed retrospectively to demonstrate the significance of our treatment scheme. The surgery was terminated only after taking a biopsy specimen in 6 patients. Other 6 patients underwent gross total resection or bulk tumor reduction. Final pathological diagnosis was malignant in 6 cases and benign in the remaining 6. Post-operative treatment was needed in 7 patients. Four operations for the 6 patients who underwent either debulking or radical surgery were performed by the binostril approach; while 5 surgeries for the 6 biopsy patients were performed by the single nostril approach. Postoperative complications were tolerable. Endoscopic resection should be adopted preferentially for benign tumors that can be removed in a piecemeal fashion. However, as most malignant tumors were impossible to resect with a negative margin, priority should be given to tumor biopsy using an endoscopic approach, which is less invasive than an open approach, and an appropriate treatment customized to the pathological diagnosis should be administered.

The Application of Three-Dimensional Technology Combined With Image Navigation in Nasal Skull Base Surgery

Three-dimensional (3D) technology including 3D reconstruction and 3D printing technology, has been widely used in clinical treatment, especially in surgical planning, and image navigation technology, which can make surgical procedures more accurate, now is also increasingly favored by surgeons. But the combination of those 2 technologies was rarely reported. Thus, this study will preliminarily investigate the feasibility and the effect of the combination of 2 technologies in endonasal skull base surgery. Eight patients were involved in this study (from October 2016 to July 2017 at The Affiliated Hospital of Qingdao University), 5 cases of nasal skull base tumors and 3 cases of foreign body perforation. All operations were done under the assistance of 3D technology and image guidance system. Surgical discussion with patient, preoperative planning and clinical teaching were investigated between 2D images and 3D models by voting. For all cases, 3D reconstruction model and 3D printed model were deemed to be more helpful than CT/MRI images in surgical discussion with the patient; surgical simulation on 3D model in preoperative planning was largely deemed to be helpful and very helpful; and in clinical teaching, 3D models combined with image guidance system were deemed to be more helpful in understanding the disease than using 2D images. Besides, all patients recovered well after surgery, no recurrence and complications were found in the follow-up. The combination of 3D technology and electromagnetic image guidance system could improve surgical efficiency and the quality of clinical teaching.

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.

Infratemporal fossa surgical approaches to primary/recurrent malignancies of salivary origin: paradigm surgical shift, patient selection, and oncologic outcomes

PURPOSE OF REVIEW

To review, the surgical approaches available on diagnosing a patient with salivary gland malignancy in the infratemporal fossa (ITF). To comment on patient evaluation and method of treatment selection. To identify and report on patient outcome data and make recommendations on future needs.

RECENT FINDINGS

There is a need to define the anatomic boundaries contents of the ITF, masticator space, parapharyngeal space (PPS), pterygopalatine fossa, ventral skull base, and paramedian skull base, as evidence from publications. The pathological subtypes identified mainly include adenoid cystic and mucoepidermoid carcinomas. The source of these tumours originates from primary disease in the sinonasal tract and nasopharynx superiorly, and the PPS/deep lobe of parotid inferiorly. Current surgical options available, in suitable selected patient, available in tertiary head and neck cancer hospitals, which have available facilities and staffing is the endoscopic endonasal approach. This approach offers patients a 'complete margin-free surgical excision', minimal complications, shorter hospital stay, and no delay with commencement of any adjuvant treatment compared with the traditional 'open transcutaneous' approach.

SUMMARY

The current evidence specifically to the surgical management of salivary gland malignancy involving the ITF is sparse, with great difficult identifying treated patients and their details among a heterogeneous group of patients with many lesions. There is a need for patient data that have specific pathologic conditions to be amalgamated from such centers and publish on outcome events.

Anatomy based corridors to the infratemporal fossa: Implications for endoscopic approaches

Background

The 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).

Methods

Six 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.

Results

The 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 space)—includes the inferior head of lateral pterygoid muscle, medial pterygoid, and temporalis muscles, and the space enclosed by these muscles.

Zone 4 (temporo‐masseteric space)—space lateral to the temporalis muscle (comprising fat mostly).

Zone 5 (tubopharyngeal space)—includes the Eustachian tube, tensor, and levator veli palatini muscles, and structures in upper parapharyngeal space.

Conclusion

The ITF can be visualized as five zones based on spaces enclosed by the masticator muscles and upper parapharyngeal structures. This novel classification system is useful to guide endoscopic approaches to the ITF, while decreasing the potential for injury of neurovascular structures and pterygoid muscles.

Adjunctive techniques to improve access of the endoscopic prelacrimal recess approach

OBJECTIVES

To determine whether adjunctive surgical techniques could improve access of instruments provided by the endoscopic prelacrimal recess approach to the anatomical boundaries of the maxillary sinus, and pterygopalatine and infratemporal fossa.

METHODS

Ten fresh-frozen adult cadaver heads were utilized. The anatomical areas of interest were fixed, bony boundaries of the maxillary sinus, infratemporal fossa, and pterygopalatine fossa: alveolar recess (AR), zygomatic recess (ZR), perpendicular plate of the palatine bone (PB), ascending ramus of mandible (RM), floor of the orbit medial and lateral to infraorbital nerve (M-ION and L-ION, respectively). Access to the areas were compared using standard sinus surgery instruments (straight and 45° forceps) introduced via the prelacrimal recess approach, trans-septal window and canine fossa puncture.

RESULTS

The prelacrimal recess approach successfully provided access to the PB and M-ION in >90% of dissections when using both the straight and 45° forceps. With the straight forceps, the ability to successfully access to the AR and ZR was the lowest at 50% and 35% respectively, although improving to 75% and 60% respectively with the 45° forceps. Access to the AR, ZR, and L-ION improved significantly when the 45° forceps was introduced through the trans-septal window. Frequency of access to the RM when either instruments when introduced through the canine fossa puncture was no greater than 60% of the dissections.

CONCLUSIONS

The addition of a small trans-septal window for instruments significantly improved access of the prelacrimal recess approach especially to the orbital floor, lateral margins of the maxillary sinus, and retromaxillary space.

LEVEL OF EVIDENCE

4 Laryngoscope, 130: 1857-1863, 2020.

Endoscopic transvestibular anatomy of the infratemporal fossa and upper parapharyngeal spaces for clinical surgery: a cadaver study

AIMS

To investigate the anatomy of the infratemporal fossa (ITF) and to discuss the practicality of endoscopic transvestibular surgery for an ITF tumor.

METHODS

Five fresh cadaveric specimens (10 sides) with vascular silicone injection were prepared for endoscopic anatomy. A transvestibular vertical incision was made along the ramus of the mandible, and pivotal nerves, arteries, and muscles were exposed to sculpt the anatomic landmarks of the ITF.

RESULTS

The endoscopic transvestibular approach exposed the detailed structure of the ITF. The buccinator muscle and the adjoining superior pharyngeal constrictor muscle shaped the paramedian border of the ITF, while the medial pterygoid muscle (MPM) and the lateral pterygoid muscle formed the lateral border. The ITF was delimited by the skull base in the upper margin, and it was proximal to the parapharyngeal space in the inferior part. The inferior alveolar nerve was the first reference point, and the maxillary artery and the lateral pterygoid muscle were also the landmarks of the ITF. The lingual nerve, the eustachian tube (ET), and the middle meningeal artery were also located in the posterior part of the ITF.

CONCLUSION

The endoscopic transvestibular approach provides a feasible and facile corridor to the ITF. With accurate hemostasis, this approach may provide another option for accessing the ITF for removal of tumors.

Gain of exposure provided by extended incision in lateral rhinotomy approach: A cadaveric study

OBJECTIVE

To assess the gain of exposure provided by extensions of the lateral rhinotomy (LR) incision, including subciliary extension, lip-splitting extension, or both (Weber-Fergusson incision), by comparing the surgical field obtained with every incision. The final goal is to better delineate the indications of each approach.

MATERIALS AND METHODS

Prospective study on fresh frozen specimens. A LR incision was first performed, and then extended by subciliary and/or lip-splitting incisions. The exposure of the anterior facial skeleton and of the deep retromaxillar spaces (pterygopalatine fossa and infratemporal fossa) were assessed. The distance between the nasal bone and the most lateral part of the exposure was measured.

RESULTS

Dissection was performed on 4 specimens, with 7 LR. Three LR incisions were extended with subciliary incision, 3 with lip-splitting incision, and 4 with Weber-Fergusson incision. LR incision alone gave only limited access to the lateral orbital rim, the zygomatic arch and the maxillary tuberosity. Both subciliary and lip-splitting incisions gave access to the lateral orbital rim and to the zygomatic arch, but only upper lip incision provided a good access to the maxillary tuberosity. Weber-Fergusson did not significantly increase the surgical field obtained with lip-splitting extension alone. The exposure of the deep retromaxillar spaces was the same in all cases.

CONCLUSION

LR incision with lip-splitting extension provided an optimal access to the anterior facial skeleton and to the maxillary tuberosity. In terms of exposure, it was equivalent to Weber-Fergusson approach. The exposure of deep spaces was the same regardless of the incision.

Neuroendoscopic Resection of Trigeminal Schwannoma in the Pterygopalatine/Infratemporal Fossa via the Transnasal Perpendicular Plate Palatine Bone or Transnasal Maxillary Sinus Approach

BACKGROUND

Both the pterygopalatine fossa (PPF) and the infratemporal fossa (ITF) lie outside the midline of the skull base. Lesions in the PPF or ITF include trigeminal schwannoma (trigeminal schwannoma, TS), which originates from the second or third branch of the trigeminal nerve (maxillary nerve or mandibular nerve). Due to their typically deep anatomic location, lesions in the PPF or ITF can be difficult to treat using traditional surgical approaches. In recent years, because of their advantages, which include the fact that they allow the problem to be observed close up, neuroendoscopic techniques are increasingly being applied in skull base surgery, especially in treatment of lesions around the midline of the base of the skull. This study aims to 1) evaluate the neuroendoscopic treatment of lesions in PPF or ITF via the transnasal palate bone perpendicular plate or transnasal maxillary sinus approach and 2) analyze the clinical significance of this approach.

METHODS

We retrospectively analyzed 3 cases of PPF TSs and 1 case of ITF TS treated between January 2015 and May 2017. All of the cases underwent neuroendoscopic resection of TSs located in the PPF via the nasal perpendicular plate palatine bone (or nasal maxillary sinus) approach.

RESULTS

Two cases of PPF TSs were characterized by a thin palate bone perpendicular plate due to oppressed absorption of the tumor. Therefore the endoscopic transnasal palate bone perpendicular plate approach was employed. Additionally, 1 case of PPF TSs and 1 case of ITF TS were resected via the transnasal maxillary sinus approach. All 4 patients received total resection under endoscopy and recovered well after their respective operations without cerebrospinal fluid leakage, although 1 patient experienced postoperative dry eye symptoms and 1 other patient showed no improvement in facial numbness before and after the operation.

CONCLUSIONS

Neuroendoscopic surgery performed via the transnasal perpendicular plate palatine bone or transnasal maxillary sinus approach has its own unique advantages in removing TSs in PPF and in ITF: Notably, the tumor can be exposed and dealt with under direct vision, which prevents damage to important structures, such as the internal carotid and maxillary nerves, while at the same time helping to achieve total removal of TSs. Furthermore, by adopting this approach versus traditional skull base surgery, postoperative trauma can be reduced significantly, which should be advocated for in this time of minimal invasive surgery.

Three-Dimensional Printed Skull Base Simulation for Transnasal Endoscopic Surgical Training

OBJECTIVE

Transnasal endoscopic skull base surgery (SBS) presents a major challenge for inexperienced neurosurgeons because of the complicated anatomic structures, 2-dimensional endoscopic view, limited operative field, and required skills. We designed a personalized multimaterial and multicolor three-dimensional (3D)-printed SBS simulation to reproduce the complex anatomy of the skull base. The fidelity and feasibility for anatomic education and surgical training were assessed.

METHODS

Two-dimensional computer tomography and magnetic resonance images were collected from a 42-year-old healthy male volunteer. After 3D modeling and spatial alignment, personalized SBS simulations were produced using a multimaterial 3D printer. The fidelity of the models was assessed by 3 experienced neurosurgeons, and the effects for anatomic education and surgical training were evaluated by 10 resident trainees. Both evaluations were based on 5-point Likert questionnaires.

RESULTS

The mean scores for fidelity of tissue structure ranged from 3.7 to 4.7, and scores for aid in anatomic education and surgical training ranged from 3.5 to 4.9.

CONCLUSION

The 3D-printed SBS simulation is a practical, economical, high-fidelity model. It has great potential for anatomic education and operative training in transnasal endoscopic surgery.

Endoscopic endonasal approach for mass resection of the pterygopalatine fossa

OBJECTIVES

Access to the pterygopalatine fossa is very difficult due to its complex anatomy. Therefore, an open approach is traditionally used, but morbidity is unavoidable. To overcome this problem, an endoscopic endonasal approach was developed as a minimally invasive procedure. The surgical aim of the present study was to evaluate the utility of the endoscopic endonasal approach for the management of both benign and malignant tumors of the pterygopalatine fossa.

METHOD

We report our experience with the endoscopic endonasal approach for the management of both benign and malignant tumors and summarize recent recommendations. A total of 13 patients underwent surgery via the endoscopic endonasal approach for pterygopalatine fossa masses from 2014 to 2016. This case group consisted of 12 benign tumors (10 juvenile nasopharyngeal angiofibromas and two schwannomas) and one malignant tumor.

RESULTS

No recurrent tumor developed during the follow-up period. One residual tumor (juvenile nasopharyngeal angiofibroma) that remained in the cavernous sinus was stable. There were no significant complications. Typical sequelae included hypesthesia of the maxillary nerve, trismus, and dry eye syndrome.

CONCLUSION

The low frequency of complications together with the high efficacy of resection support the use of the endoscopic endonasal approach as a feasible, safe, and beneficial technique for the management of masses in the pterygopalatine fossa.