Effect of Incremental Endoscopic Maxillectomy on Surgical Exposure of the Pterygopalatine and Infratemporal Fossae

Radiological examination of greater palatine canal medial wall dehiscence

INTRODUCTION

The greater palatine canal (GPC) connects the pterygopalatine fossa to the greater palatine foramen and houses vital neurovascular structures, which provide sensory innervation and circulation to the gums, palate, and nasal cavity. The GPC is of great clinical importance to various medical specialties; however, the anatomical variability of the GPC poses a risk of iatrogenic injury and complications. Therefore, understanding the normal anatomy and variations of the GPC is crucial for identifying vital structures and minimizing risks in clinical practice.

PURPOSE

The aim was to fill a gap in the current literature by focusing on the prevalence of GPC medial wall dehiscence, a lesser-known anatomic variation, in radiological scans.

METHODS

A total of 200 head and neck CT scans were examined, where 71 scans met the inclusion criteria. Statistical significance for incidence of GPC medial wall dehiscence, in reference to sex and side, was measured.

RESULTS

The GPC medial wall dehiscence was observed in 69% of scans. Bilateral dehiscence was seen in 57.7% of scans, while right-sided and left-sided unilateral dehiscence were found in 14.1% and 11.3%, respectively. Significant difference was found between the incidence of bilateral dehiscence compared to the absence of dehiscence.

CONCLUSION

Previous studies have highlighted the potential risks associated with invasive procedures involving the GPC. The clinical relevance of GPC medial wall dehiscence lies in the increased risk of transecting the contained neurovascular bundle. The presence of dehiscence emphasizes the need for meticulous preoperative radiologic analysis to tailor surgical approaches to individual patient anatomy.

Management of the Nasolacrimal Duct in Expanded Endoscopic Approaches to the Maxillary Sinus: A Systematic Review with Evidence-based Recommendations

BACKGROUND

Utilizing expanded endoscopic approaches to the maxillary sinus for the endonasal management of a variety of tumors is increasing in popularity. The nasolacrimal duct (NLD) may be injured inadvertantly or need to be removed during tumor resection or to augment visualization. Management of the NLD can take the form of transection alone, transection with stenting, or performing a formal dacryocystorhinostomy to avoid postoperative sequelae of injury. The purpose of this study was to review the literature and determine the optimal management of the NLD during expanded maxillary sinus approaches.

METHODS

A systematic review of Ovid, Embase, Medline, and Cochrane databases was performed to identify studies involving expanded approaches to the maxillary sinus and that explicitly reported the status of the NLD and postoperative outcomes.

RESULTS

Nineteen studies were included in the analysis and divided into two groups: NLD-preserving (n = 9 studies; n = 191 patients in aggregate) and NLD-involving (n = 10 studies; n = 296 patients in aggregate). In the NLD-preserving subgroup, one patient out of a subgroup aggregate of 191 patients (0.5%) developed epiphora. In the NLD-involving subgroup, sharp transection alone was the most common method of NLD removal and was associated with a low rate of epiphora (study rates: 0 to 18.2%; aggregated subgroup rate: 7.0%, 21 / 296). Spontaneous resolution of symptoms was common (60%-100% cases).

CONCLUSIONS

The NLD should be preserved when feasible from an exposure and tumor-control perspective. When pathology or approach requires the removal of the NLD, rates of persistent epiphora are very low, regardless of surgical technique. When expanded maxillary approaches are employed, particularly for benign tumors, and require removal of the NLD, sharp transection is the simplest method of removal, provides a low rate of postoperative epiphora, and is supported by the available literature.

Anterior endoscopic sublabial transmaxillary access to middle cranial base lesions

BACKGROUND

Anterior endoscopic access to middle cranial base lesions becomes feasible in the presence of infratemporal fossa (ITF) involvement. Various approaches, including endoscopic endonasal, transoral sublabial, and transorbital methods, have been described for accessing the ITF through a transmaxillary corridor. Among these approaches, endonasal access is the most commonly preferred, while the transorbital approach is a novel technique gaining popularity. The transoral sublabial approach is considered suitable for selected lesions.

METHODS

Patients who underwent the anterior endoscopic transoral/sublabial transmaxillary approach to middle cranial base lesions at a single institute from 2016 to 2023 were included in this retrospective study. Malignant lesions were excluded from the study. The sublabial approach was exclusively performed in all cases, with the exception of one patient who required a combined approach.

RESULTS

The anterior endoscopic transoral sublabial transmaxillary approach to the infratemporal fossa, upper parapharyngeal space, and middle cranial fossa was performed on 14 patients. The underlying conditions for these patients were as follows: trigeminal schwannomas (n = 8), meningiomas (n = 2), juvenile nasopharyngeal angiofibroma, osteochondroma, arachnoid cyst and encephalocele (n = 1 each). Gross total resection was achieved in 11 cases. The most common complication was numbness in the territory of the maxillary and mandibular nerves (n = 4). Two patients needed endoscopic maxillary antrostomy for persistent suppuration. No wound problems or CSF rhinorrhea occurred. The average follow-up time was 26.6 months.

CONCLUSION

The endoscopic sublabial transmaxillary approach provides direct access to the infratemporal fossa and middle cranial base, enhancing the surgical range of maneuverability while sparing the sinonasal cavity. This procedure is safe, less invasive, and could be used as an efficient corridor for the resection of selected infratemporal fossa lesions with or without extension to the middle cranial base and parapharyngeal space.

An endoscopic transnasal prelacrimal recess transmaxillary approach to the pterygopalatine fossa and infratemporal fossa

Objective

In this paper, the goal of the authors is to present the anatomic nuances and their clinical experience with lesions of the pterygopalatine fossa and infratemporal fossa using an endoscopic transnasal prelacrimal recess transmaxillary approach (PLRMA).

Methods

An endoscopic anatomical dissection of three fresh cadaveric heads was performed bilaterally to evaluate the feasibility of the PLRMA. Prior to dissection, stereotactic computed tomography scans were obtained for each head to obtain anatomical measurements. The area of exposure on the posterior wall of the maxillary sinus was determined using stereotaxis. The cases of six patients with schwannomas or epidermoid cysts who underwent the transnasal PLRMA were illustrated.

Results

The mean area of exposure on the posterior wall of the maxillary sinus was 9.55 cm2. Total resection was achieved in all six patients. The mean follow-up time was 16 months, and one patient complained of postoperative facial numbness, which resolved gradually. No cases of chronic sinusitis were reported.

Conclusions

The endoscopic transnasal PLRMA provides efficient operative exposure to the pterygopalatine fossa and infratemporal fossa. Preserving the integrity of the mucosa on the nasal lateral wall is an advantage of this approach.

Anatomical Computerized Exploration to Excise Malignancies in Deep Facial Compartments: An Advanced Virtual Reality Protocol for a Tailored Surgical Approach

Objective/Hypothesis

This study describes the design and application of a novel advanced protocol for virtual three-dimensional anatomical reconstruction of the deep facial compartments, aiming to improve the preoperative understanding and the intraoperative assistance in complex resective surgeries performed for malignant diseases which extend in complex spaces, including the pterygomaxillopalatine fossa, the masticator space, and the infratemporal fossa.

Methods

This study is a non-profit, retrospective, and single-institution case series. The authors clearly describe in detail imaging acquisition protocols which are suitable to segment each target, and a multilayer reconstruction technique is presented to simulate anatomical structures, with particular focus on vascular networks. Virtual surgical planning techniques are individually designed for each case to provide the most effective access to the deep facial compartments. Intraoperative guidance systems, including navigation and virtual endoscopy, are presented, and their role is analyzed.

Results

The study included seven patients with malignant disease located in the deep facial compartments requiring radical resection, and all patients underwent successful application of the protocol. All lesions, except one, were subject to macroscopically radical resection. Vascular structures were identified with overall reconstruction rates superior to 90% for major caliber vessels. Prominent landmarks for virtual endoscopy were identified for each case.

Conclusions

Virtual surgical planning and multilayer anatomical reconstruction are valuable methods to implement for surgeries in deep facial compartments, providing the surgeon with improved understanding of the preoperative condition and intraoperative guidance in critical phases for both open and endoscopic phases. Such techniques allow to tailor each surgical access, limiting morbidity to strictly necessary approaches to reach the disease target.

Defining the limits and indications of the Draf III endoscopic approach to the lateral frontal sinus and maximizing visualization and maneuverability: a cadaveric and radiological study

PURPOSE

The DRAF III procedure has been used for access to the lateralmost part of the frontal sinus. We sought to identify anatomical and radiological measurements as well as modifications that predict the lateral limits of visualization and surgical access after this procedure.

METHODS

Seven cadaver heads were imaged with computed tomography scan. The distance from midline to the medial orbital wall (MOWD), midline to the lateral end of the frontal sinus (MLD), the sum of MLDs (SMLD), interorbital distance (IOD) and the shortest anteroposterior distance of the frontal recess (APD) were utilized. The ratios MLD/MOWD, and SMLD/IOD were calculated. The same distances were measured on 41 CT scans. Orbital transposition (OT) and partial resection of the piriform aperture (PAR) were performed; the visualization and reach were assessed. The angle of insertion was measured before and after the modifications.

RESULTS

Only the ratio MLD/MOWD was consistently predictive of access to the lateral, superior and posterior wall of the frontal sinus. Following the modifications, a visualization of 100% laterally was achieved with the 30- and 45 degree endoscopes and every lateral recess could be reached with the 70 degree suction. A mean increase of the angle of insertion of 25.3 and 59.6% was recorded after OT and PAR, respectively.

CONCLUSIONS

IOD rather than APD defines the limits of the Draf III approach to the lateral frontal sinus and MLD/MOWD ratio can serve as a useful preoperative tool. Along to the already described OT, PAR increases visualization and reach of the lateral frontal sinus.

Evaluating Endoscopic Ipsilateral Endonasal Corridor Approaches to the Anterolateral Wall of the Maxillary Sinus: A Computerized Tomography Study

Introduction  The endoscopic access to lesions in the anterolateral wall of the maxillary sinus is a challenging issue; therefore, the evaluation of access should be performed.

Objective  To assess the accessibility of three endoscopic ipsilateral endonasal corridors.

Methods  Three corridors were created in each of the 30 maxillary sinuses from 19 head cadavers. Accessing the anterolateral wall of the maxillary sinus was documented with a straight stereotactic navigator probe at the level of the nasal floor and of the axilla of the inferior turbinate.

Results  At level of the nasal floor, the prelacrimal approach, the modified endoscopic Denker approach, and the endoscopic Denker approach allowed mean radial access to the anterolateral maxillary sinus wall of 42.6 ± 7.3 (95% confidence interval [CI]: 39.9–45.3), 56.0 ± 6.1 (95%CI: 53.7–58.3), and 60.1 ± 6.2 (95%CI: 57.8–62.4), respectively. Furthermore, these approaches provided more lateral access to the maxillary sinus at the level of the axilla of the inferior turbinate, with mean radial access of 45.8 ± 6.9 (95%CI: 43.3–48.4) for the prelacrimal approach, 59.8 ± 4.7 (95% CI:58.1–61.6) for the modified endoscopic Denker approach, and 63.6 ± 5.5 (95%CI: 61.6–65.7) for the endoscopic Denker approach. The mean radial access in each corridor, either at the level of the nasal floor or the axilla of the inferior turbinate, showed a statistically significant difference in all comparison approaches ( p  < 0.05).

Conclusions  The prelacrimal approach provided a narrow radial access, which allows access to anteromedial lesions of the maxillary sinus, whereas the modified endoscopic Denker and the endoscopic Denker approaches provided more lateral radial access and improved operational feasibility on far anterolateral maxillary sinus lesions.

Extended Anterior Inferior Approach to Endoscopic Medial Maxillectomy for Maxillary Sinus Lesions

BACKGROUND

Myriad open and endoscopic approaches are employed to resect maxillary sinus lesions, each with associated advantages and disadvantages. The inferior and anterior portion of the sinus remains a challenging space to access.

OBJECTIVES

To describe the extended anterior inferior approach to endoscopic medial maxillectomy (EAMM) as a novel and valuable addition to a stepwise approach for minimizing surgical morbidity without compromising tumor outcomes. To report the outcomes of patients treated with this approach.

METHODS

A retrospective case series study of 9 patients who underwent EAMM between 2016 and 2019 at a tertiary care referral center was performed. The endoscopic technique is described. The duration of follow-up ranged from 1 to 53 months. Intraoperative steps, including transection of the nasolacrimal duct and execution of an intraoperative dacryocystorhinostomy, were reviewed. Postoperative outcomes, including patient symptoms at follow-up and tumor recurrence, were recorded.

RESULTS

Adequate exposure with gross total tumor resection or margin-negative tumor resection was achieved in all cases. Sparing of the nasolacrimal duct was achieved in 2 patients. No patients reported persistent epiphora, empty nose syndrome, or changes in cosmesis such as alar or nasal tip collapse. One patient reported unilateral V2 hypoesthesia at 6 months postoperatively that had resolved by his next follow-up 18 months after surgery. Postoperative tumor surveillance was achieved by endoscopic examinations in all patients and there was no evidence of tumor recurrence at a median follow-up of 22 months.

CONCLUSIONS

The EAMM provides improved access to the inferior-posterior-medial maxillary sinus. This approach minimizes the risk of hypoesthesia and change in cosmesis present in other approaches, and obviates division of the nasolacrimal duct for inferior, posterior-medial attached lesions. This progressive escalation of approach for maxillary sinus lesions minimizes injury to nasal and nasolacrimal structures without compromising tumor outcomes.

Endoscopic maxillectomy: anatomo-radiological description of the "double" maxillary sinus window

OBJECTIVES/HYPOTHESIS

To present a modified endoscopic medial maxillectomy (MEMM) approach to control maxillary sinus pathologies.

METHODS

MEMM was completed in 13 fresh-frozen specimens. An MEMM includes cutting the nasolacrimal duct, inferior meatus flap, and repositioning the inferior turbinate (IT). The following measurements were obtained: length of IT, height from the nasal floor to valve of Hasner, height of the IT at the level of valve of Hasner, height of the IT at the insertion of the middle turbinate, and distance from the piriform aperture to the posterior wall of maxillary sinus and to the posterior border of palatine bone. Similar measurements were also performed on craniofacial computed tomography (CT) scans (n = 50). The surgical technique was performed in a case series (n = 8).

RESULTS

The mean of the specimens was 82 (range 70-95) years old. The average area of the harvested inferior meatus flap area was 9.6 ± 1.0 cm². In the radiologic study, the mean maximum antrostomy area was 8.8 ± 1.7 cm² and the IT area overlapping the antral window was 5.8 ± 1.1 cm², the area allowing a double window control was 3.1 ± 1.9 cm², the posterior IT insertion length was 0.7 ± 0.4 cm, and the inferior meatus flap covering the inferior meatotomy had an area measuring 6.7 ± 1.7 cm². Eight patients underwent MEMM for various benign conditions showing no recurrence after 26 month follow-up.

CONCLUSION

The proposed modifications of MEMM provide a "double" window maxillary sinus control with access to all maxillary walls and preservation of the IT.

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.

Endoscopic Denker's Approach for the Treatment of Extensive Sinonasal Tumors: Our Experience

OBJECTIVES

Surgical management of large sinonasal tumors, spreading to the pterygopalatine, and infratemporal fossae have always been a challenge for the ENT surgeon and the multidisciplinary team.

METHODS

Endoscopic Denker's approach allows complete exposure of the anterior, inferior, and lateral recesses of the maxillary sinus, without necessitating a gingivobuccal or a transseptal incision. Moreover, endoscopic Denker's approach facilitates direct, straight entry to the pterygopalatine and infratemporal fossae.

RESULTS

Twenty-two patients with extensive sinonasal pathology underwent resection via an endoscopic Denker's approach at our institution, with the majority of them being diagnosed with JNA and inverted papilloma. Denker's procedure facilitated wide exposure of the surgical field and total tumor resection, without significant perioperative complications and good disease-free results in follow up.

CONCLUSIONS

Our experience is in accordance with the literature, where this approach seems to be superior to alternative options for accessing the pterygopalatine and infratemporal fossae. We believe that adequate expertise in endoscopic sinonasal surgery is necessary prior to embarking on this technique, but in general, it represents a valuable tool in the surgeon's armamentarium.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1458-1462, 2021.

Endoscopic transoral nasopharyngectomy

BACKGROUND

A minimal access technique for the management of nasopharyngeal tumors extending below the palatal plane and laterally beyond the pterygoid musculature is yet to be developed. In this study we demonstrate the feasibility of endoscopic transoral nasopharyngectomy (ETON) for resection of large nasopharyngeal lesions as a natural orifice alternative to traditional approaches.

METHODS

ETON was completed in three latex-injected specimens. Surgical freedom (SF) and angles of attack (AoA) were calculated along the internal carotid artery (ICA).

RESULTS

An endoscopic transoral approach was successfully used to identify the parapharyngeal ICA and subsequently perform a complete nasopharyngeal resection. SF and AoA (sagittal) were found to be the greatest at the anterior genu of the ICA.

CONCLUSIONS

ETON is feasible. It provides wide exposure of the skull base and proximal control of the ICA. It may be indicated for the management of nasopharyngeal tumors with inferolateral extension, involving the ICA.

Ventilated Upper Airway Endoscopic Endonasal Procedure Mask: Surgical Safety in the COVID-19 Era

BACKGROUND

COVID-19 poses a risk to the endoscopic skull base surgeon. Significant efforts to improving safety have been employed, including the use of personal protective equipment, preoperative COVID-19 testing, and recently the use of a modified surgical mask barrier.

OBJECTIVE

To reduce the risks of pathogen transmission during endoscopic skull base surgery.

METHODS

This study was exempt from Institutional Review Board approval. Our study utilizes a 3-dimensional (3D)-printed mask with an anterior aperture fitted with a surgical glove with ports designed to allow for surgical instrumentation and side ports to accommodate suction ventilation and an endotracheal tube. As an alternative, a modified laparoscopic surgery trocar served as a port for instruments, and, on the contralateral side, rubber tubing was used over the endoscrub endosheath to create an airtight seal. Surgical freedom and aerosolization were tested in both modalities.

RESULTS

The ventilated mask allowed for excellent surgical maneuverability and freedom. The trocar system was effective for posterior surgical procedures, allowing access to critical paramedian structures, and afforded a superior surgical seal, but was limited in terms of visualization and maneuverability during anterior approaches. Aerosolization was reduced using both the mask and nasal trocar.

CONCLUSION

The ventilated upper airway endoscopic procedure mask allows for a sealed surgical barrier during endoscopic skull base surgery and may play a critical role in advancing skull base surgery in the COVID-19 era. The nasal trocar may be a useful alternative in instances where 3D printing is not available. Additional studies are needed to validate these preliminary findings.

Extended endoscopic approaches to the maxillary sinus

OBJECTIVES

Treatment of inflammatory and neoplastic disease in the maxillary sinus, pterygopalatine and infratemporal fossae requires appropriate surgical exposure. As modern rhinology evolves, so do the techniques available. This paper reviews extended endoscopic approaches to the maxillary sinus and the evidence supporting each technique.

METHODS

A literature search of the Ovid Medline and PubMed databases was performed using appropriate key words relating to endoscopic approaches to the maxillary sinus.

RESULTS

Mega-antrostomy and medial maxillectomy have a role in the surgical treatment of refractory inflammatory disease and sinonasal neoplasms. The pre-lacrimal fossa approach provides excellent access but can be limited because of anatomical variations. Both the transseptal and endoscopic Denker's approaches were reviewed; these appear to be associated with morbidity, without any significant increase in exposure over the afore-described approaches.

CONCLUSION

A range of extended endoscopic approaches to the maxillary sinus exist, each with its own anatomical limitations and potential complications.

Endonasal endoscopic transpterygoid approach to the upper parapharyngeal space

BACKGROUND

Lesions of the upper parapharyngeal space (UPPS) present a surgical challenge. The objective of this study was to ascertain the feasibility of a novel technique of modified transpterygoid approach to the UPPS.

METHODS

Six fresh cadaveric specimens (12 sides) were dissected, developing a technique that includes en bloc mobilization of the lateral pterygoid plate and muscle to access the UPPS.

RESULTS

Following an endoscopic Denker's approach and the removal of posterolateral wall of the antrum, the lateral pterygoid plate was detached from the pterygoid process. Subsequently, the lateral pterygoid plate and muscle were displaced laterally as a unit, allowing the identification of the posterior trunk of V₃ and the fat in prestyloid compartment. Dissecting off the styloid aponeurosis affords entering the poststyloid UPPS exposing the internal carotid artery, internal jugular vein, and cranial nerves IX to XII.

CONCLUSION

This novel modification of the endonasal transpterygoid approach offers a viable alternative for access to the UPPS.

Single-stage endoscopic endonasal approach for the complete removal of trigeminal schwannomas occupying both the middle and posterior fossae

To introduce a purely endoscopic endonasal trans-Meckel's cave approach or a transclival approach for trigeminal schwannomas (TSs) involving both the middle and posterior fossae. This retrospective study reviewed the medical records and intraoperative videos of 8 patients with TSs occupying both the middle and posterior fossae who underwent an endoscopic endonasal approach (EEA) between January 2017 and October 2019. All 8 patients received total resection under a single-stage EEA. Six patients underwent endoscopic endonasal resection via a purely trans-Meckel's cave approach, and 2 patients underwent endoscopic endonasal resection via a trans-Meckel's cave approach combined with a transclival approach. There was no surgical-related hemorrhage or mortality and no cerebrospinal fluid leakage. All headache symptoms completely improved postoperatively (n = 3 patients). All cranial nerve (CN) symptoms (CN IX and CN VI) improved postoperatively. The most common preoperative symptom was facial numbness (n = 5 patients); 2 of these 5 patients showed a partial improvement, 1 patient experienced worsening, and 2 patients remained unchanged at the last follow-up. Four patients developed postoperative complications, including CN VI palsy (n = 2), dry eye (n = 2), mastication weakness (n = 1), and facial numbness (n = 2). All complications except for dry eye were relieved at the last follow-up, but the patients with dry eye did not develop corneal keratopathy. The endoscopic endonasal trans-Meckel's cave and transclival approaches provide adequate exposure and improve the rate of total resection for TSs occupying both the middle and posterior fossae with minimal invasion. It may be possible to use these approaches as a safe alternative to conventional surgical approaches.

[Use of navigation in skull base surgery]

The review briefly presents the history of development of navigation systems in neurosurgery. The idea of the existing principles underlying the navigation systems used in neurosurgery is given. Currently, the basic principles of navigation are optical and electromagnetic. Studies are presented comparing the accuracy of various navigation systems. Optical navigation demonstrates greater accuracy compared to electromagnetic, but both methods demonstrate a submillimeter error in the experiment. The history of use of navigation in the surgery of the skull base is analyzed in detail, the most relevant areas of use of navigation within the surgery of the skull base are considered: craniofacial reconstruction, endoscopic endonasal surgery, surgery of common tumors of the skull base affecting the infratemporal, pterygopalatine fossa, temporomandibular joint. Indications for the use of navigation, limitations of the methodology are explained.

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.

Endoscopic-Assisted Lateral Corridor to the Infratemporal Fossa: Proposal and Quantitative Comparison to the Endoscopic Transpterygoid Approach

Objective  This study was aimed to propose an expanded endoscopic-assisted lateral approach to the infratemporal fossa (ITF) and compare its area of exposure and surgical freedom with the endoscopic endonasal transptergyoid approach (EETA). Methods  Anatomical dissections were performed in five cadaver heads (10 sides). The ITF was first examined through the endoscopically assisted lateral corridor, herein referred to as the endoscopic-assisted transtemporal fossa approach (TTFA). After that, the EETA was performed and coupled with two sequential maxillary procedures (medial maxillectomy [MM], and endoscopic-assisted Denker's approach [DA]). Using the stereotactic neuronavigation, measurements of the area of exposure and surgical freedom at the foramen ovale were determined for the previously mentioned approaches. Results  Bimanual exploration of the ITF through the endoscopic-assisted lateral approach was achieved in all specimens. The DA (729 ± 49 mm ² ) provided a larger area of exposure than MM (568 ± 46 mm ² ; p <  0.0001). However, areas of exposure were similar between the DA and the TTFA (677 ± 35 mm ² ; p  = 0.09). The surgical freedom offered by the TTFA (109.3 ± 19 cm ² ) was much greater than the DA (24.7 ± 4.8 cm ² ; p <  0.0001), and the MM (15.2 ± 3.2 cm ² , p <  0.0001). Conclusion  The study demonstrates the feasibility of the proposed approach to provide direct access to the extreme extensions of the ITF. The lateral corridor offers an ideal working area in the posterior compartment of the ITF without crossing over important neurovascular structures. The new technique may be used alone in selected primary ITF lesions or in combination with endonasal approaches in pathologies spreading laterally from the nose or nasopharynx.

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.

Endoscope-assisted contralateral transmaxillary approach to the clivus and the hypoglossal canal: technical case report

Clival lesions are still considered surgically complex due to their anatomical location. Critical structures, such as the internal carotid arteries (ICAs), cavernous sinuses, cranial nerves, and brainstem, may be encased within the lesion. Although advances in endoscopic endonasal approaches have provided new routes to these lesions, exposure and resection of clival tumors through the endonasal route remain a technical challenge. Here, the authors report a left-sided endoscopic transmaxillary approach to access the right aspect of the clivus and the hypoglossal canal.A 35-year-old woman presented with progressive right 6th cranial nerve palsy. MRI revealed a contrast-enhancing right petroclival chondrosarcoma that involved Meckel's cave and extended into the right hypoglossal canal. An endoscopic-contralateral-transmaxillary approach through a left sublabial incision was used to access the right petroclival region and right hypoglossal canal. A left maxillary osteoplastic flap was elevated to expose the left maxillary sinus. This was followed by a left medial maxillectomy, gaining access to the left posterior nasal cavity. The posterior third of the left inferior turbinate and nasal septum were removed to access the right side of the petroclival region. Near-total resection was achieved without any vascular or neurological complications. A thin shell of residual tumor was left behind due to involvement of vital structures, such as the ICA, and further treated with proton-beam radiotherapy.The endoscopic-contralateral-transmaxillary approach provides a direct surgical corridor and good lateral visualization of the skull base vasculature. This approach allows wide maneuverability around the ICA and hypoglossal canal, which, in this case, allowed maximal tumor resection with full preservation of neurological function.

Modified endoscopic endonasal approach with a minimally invasive transoral approach-an adjunct to infrapetrous approaches

OBJECTIVES/HYPOTHESIS

To evaluate the potential of a minimally invasive transoral-transpalatal approach (MITA) to the retrocarotid petrous apex, as an adjunct to endoscopic endonasal approaches (EEAs).

STUDY DESIGN

Cadaver study.

METHODS

Five cadaveric specimens were dissected raising an inverted U-shaped palatal mucoperiosteal flap, and drilling a rectangular palatotomy (between the greater palatine foramens, and just anterior to the palatine aponeurosis). This allowed a transpterygoid EEA with cross-court access (contralateral line of sight), followed by an extradural clivectomy that exposed the petroclival junction bilaterally. Surgical targets were marked on the posterior and medial surface of the petrous internal carotid artery (ICA), at its anterior genu, midhorizontal portion, and posterior genu. For each target and approach, the surgical freedom and angles of approach (in the horizontal and vertical planes) were calculated and statistically compared.

RESULTS

Compared to EEA, the MITA resulted in greater surgical freedom for all targets, with the highest values at the anterior genu (1,661.37 mm² vs. 312.76 mm² , P <.001), and maintaining superiority in this regard all the way to the posterior genu (847.84 mm³ vs. 138.91 mm³ , P < .005). MITA also offered greater angles of approach for all targets.

CONCLUSIONS

This study suggests that the MITA may be indicated to supplement the exposure provided by a transpterygoid EEA. This technique, associated with low potential morbidity, offers an alternative to internal carotid lateralization while managing extradural lesions that are adjacent to the petrous ICA.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:339-343, 2019.

Computed Tomography Research: Relative Anatomy of Caldwell-Luc Approach in Pterygopalatine Fossa Surgery

With the development of endoscopic technique, Caldwell-Luc approach has more wide applications and becomes a common method of pterygopalatine fossa (PPF) surgery. Few data can be used in this approach to avoid injuring the vessels and nerves within this area. In this study, the authors used computed tomography to get the coordinates of inferior orbital fissure, foramen rotundum, sphenopalatine foramen, internal opening of pterygoid canal, the strangulation of PPF, and the greater palatine foramen with canine fossa as the origin. Parameters of 60 patients (120 observations) between 35 and 55 years who have no experience of trauma or surgery before were involved in this study. The data were analyzed by SPSS, statistical software with the comparison between sexes and sides. After calculating the relative distances and angles between these points and canine fossa, the authors get the proportions of the upper part of PPF, and the pterygopalatine canal to PPF, respectively. The authors finally got the safety surgical range. The results are meaningful to safety in surgery and complication avoidance, which can be great references in clinical applications.

Minimally Invasive Lateral Endoscopic Multiport Approach to the Infratemporal Fossa: A Cadaveric Study

BACKGROUND

Expanded endoscopic endonasal approaches to the infratemporal fossa (ITF) are increasingly performed owing to improved visualization and less morbidity compared with classic open approaches. Only a few studies in the literature investigated lateral endoscopic access to the ITF. The aim of this study was to examine the ITF with the minimally invasive endoscopically assisted Gillies approach with a trial of its expansion through a double port technique.

METHODS

The ITF was examined in 10 sides of 5 cadaveric heads using a lateral endoscopic assisted approach. A double portal technique was developed to allow bimanual dissection. Specific long angled skull base instruments were used for dissection under stereotactic guidance.

RESULTS

The endoscopic assisted Gillies approach permitted minimally invasive access to the complete anteroposterior extension of the ITF with sufficient mobility of surgical instruments. A new anatomic classification for the ITF from a lateral endoscopic perspective was introduced. The addition of the second port allowed bimanual dissection.

CONCLUSIONS

This cadaveric study shows the feasibility of an endoscopically assisted lateral approach to the ITF. The addition of a posterior port expands the approach through increasing the working area and enabling a bimanual dissection technique. Performed alone or combined with an anterior endoscopic transnasal approach, this technique offers minimally invasive access to the ITF. The development of specifically designed instruments would further improve this promising approach.

Endoscopic endonasal approach for trigeminal schwannomas: our experience of 39 patients in 10 years

BACKGROUND

The anatomical locations involved in trigeminal schwannomas (TSs) are quite complex. The endoscopic endonasal approach provides a minimal damage access corridor to both anterior and middle skull base for surgery. Given the nerve function recovery and postoperative neurological deterioration varied in different reports, the author demonstrates his surgery tips and the functional outcomes under endoscopic surgery in one single institution.

METHODS

A retrospective review of patients with TSs was undertaken to assess the outcome of endoscopic surgery from 2006 to 2016. Clinical features, imaging findings, preoperative/postoperative neurological deficits, surgical approaches and followed up data were collected.

RESULTS

Thirty-nine patients with TSs were included in this study. Surgical approaches include endoscopic medial maxillectomy approach (n = 8), endoscopic endonasal-assisted sublabial transmaxillary approach (n = 27) and endoscopic endonasal-assisted sublabial transmaxillary combined with septectomy (n = 4). Gross total resection and sub-total resection were achieved in 27 and 10 patients, respectively. The most common chief complaint was facial numbness, accounting for 41%, with a resolved rate of 62.5% after treatment. Fifteen patients developed new neurologic symptoms, including facial numbness/pain (n = 9 and 2, respectively), dry eye (n = 3) and mastication weakness (n = 1). Eight of these patients had partial improvement except for patients with dry eye.

CONCLUSION

Endoscopic endonasal approach represents a safe and effective surgical procedure for TSs in pterygopalatine fossa, infratemporal fossa and even Meckel cave. Tumor resection can be achieved by endoscope with few neurologic deficits and complications.

Anterior superior alveolar nerve injury after extended endoscopic medial maxillectomy: a preclinical study to predict neurological morbidity

BACKGROUND

Endoscopic medial maxillectomies (EMMs) are used to optimize exposure of the maxillary sinus and retromaxillary areas. Although in type D EMM (Sturmann-Canfield procedure) the anterior superior alveolar nerve (ASAN) is always at risk of injury, only 29% of patients complained of alveolar process and dental anesthesia. The purpose of this anatomical study is to assess the neural anastomotic network of the ASAN (ASAN-NAN) and describe different extensions of type D EMMs in a preclinical setting.

METHODS

The ASAN and its medial anastomotic branches (MABs) and lateral anastomotic branches (LABs) were evaluated by cone-beam computerized tomography (CBCT). Five different extensions of type D (D1 to D5) EMMs were identified and nerves at risk of injury in each type were assessed by CBCT. Moreover, quantification of surgical corridors was performed on cadaver heads with a neuronavigation system.

RESULTS

Fifty-seven CBCT scans were analyzed. The ASAN would be spared in 16.3% of cases with a type D1 EMM, while it would be injured in the majority of type D2 to D5 resections. At least 1 nerve of the ASAN-NAN was spared in 96.6%, 93%, 74.6%, 0%, and 65.8% of type D1 to D5 EMMs, respectively. Two cadaver heads were dissected and the incremental volume and number of maxillary subsites exposed was assessed in type D1 to D5 EMMs.

CONCLUSION

ASAN function impairment is probably compensated by LABs and MABs. If this hypothesis will be validated in a prospective study on patients, preoperative CBCT evaluation could predict neurological morbidity after type D EMM, and allow tailoring the procedure to minimize impairment of the ASAN-NAN.

Radioanatomic Study of the Greater Palatine Canal Relevant to Endoscopic Endonasal Surgical Landmarks

Objective A radioanatomic study of surgically relevant variations in the greater palatine canal (GPC) on computed tomography (CT) was performed to determine susceptibility during endoscopic endonasal procedures. Study Design Blinded radioanatomic analysis. Setting Tertiary university hospital. Subjects and Methods Fifty consecutive paranasal CT scans (100 sides) were analyzed. Measurements were standardized to landmarks such as the inferior turbinate (IT) and floor of the nasal cavity (FNC) to assess variability and vulnerability of the nerve. Measurements included (1) incidence of maxillary sinus pneumatization posterior to the GPC, (2) distance from the posterior wall of the maxillary sinus to the GPC at the IT and FNC, (3) width of bone containing the GPC, (4) incidence of medial GPC dehiscence, and (5) angle of the GPC extending from the IT to FNC. Results Ninety-one percent of maxillary sinuses were pneumatized posterior to the GPC. The distance from the posterior wall of the maxillary sinus to the GPC was 2.8 ± 1.7 mm (range, -2.3 to 5.9) at the posterior attachment of the IT and 4.1 ± 3.1 mm (range, -6.3 to 11.9) at the FNC. The width of bone containing the GPC was 3.3 ± 1.3 mm (range, 1-8.9), and the medial bony GPC was dehiscent in 38% of cases. In the sagittal plane, the angle of the GPC between the IT and the FNC was 31.9 ± 6.9 degrees (range, 10.8-45). Conclusion The GPC has considerable anatomic variability relative to important surgical landmarks in endoscopic procedures. Preoperative review of CTs to assess vulnerability may prevent postoperative complications.

Modular Endoscopic Medial Maxillectomies: Quantitative Analysis of Surgical Exposure in a Preclinical Setting

BACKGROUND

The nomenclature adopted for endoscopic medial maxillectomies (EMMs) is exceedingly heterogeneous. The aim of this study was to objectively measure surgical exposure in a preclinical anatomic setting to validate a classification for modular EMMs.

MATERIALS AND METHODS

Computed tomography was used to scan 6 cadaver heads, and images were uploaded on dedicated software. A neuronavigation system was used to measure areas and volumes of surgical corridors during dissection. Differences of >10% of area exposed and >3 cm³ of volume were considered to define incremental types of EMM. Specific anatomic targets were assessed on the axial and sagittal planes. Influence of anatomic variants on surgical exposure was evaluated.

RESULTS

There were 4 types of EMMs (A-D), with a transseptal variant for each, identified. In the axial plane, type A exposed the vidian canal and foramen rotundum, type B exposed the foramen ovale and foramen spinosum, and transseptal type C or type D exposed the coronoid process. In the sagittal plane, type A exposed the vidian canal, and type B exposed the foramen ovale and styloid process. Transseptal type C exposed the pterygomaxillary fissure, and type D exposed the inferior border of the lateral pterygoid plate. The nasal floor limits the downward angle in transseptal approaches. The width of the piriform aperture independently influenced surgical volume of types B and C.

CONCLUSIONS

This modular classification of EMMs, based on quantitative analysis in a preclinical setting, should allow for better personalized preoperative surgical planning and provides standardization of nomenclature.