A Comparative Analysis of Endoscopic-Assisted Transoral and Transnasal Approaches to Parapharyngeal Space: A Cadaveric Study

Anatomical limits of the parapharyngeal space using a transoral endoscopic approach - Radioanatomical study in cadaver

PURPOSE

The aim of this study is to obtain the anatomical limits of the parapharyngeal space by transoral surgical approach, in order to objectively determine the types of lesions according to location, where this type of approach is more indicated.

METHODS

A prospective, experimental, radio-anatomical study was performed on 10 cryopreserved human heads(20 sides). A transoral approach of the parapharyngeal space was performed determining its anatomical limits by CT navigation. A statistical analysis of the registered variables was carried out.

RESULTS

Intraoral endoscopic dissection of the parapharyngeal space was possible in all anatomical pieces (10 heads, 20 sides). The surgical technique was started by placing a laryngopharyngoscopic retractor. The scalpel incision was made from the posterior border of the hard palate, extending along the lateral border of the soft palate, following the glossopalatine arch and ending at the base of the tongue, in its posterolateral region. Under direct vision with a 0º rigid endoscope, we proceeded to the dissection by planes, identifying all the relevant vasculonervous, osseous and muscular structures. Once all the anatomical references were located, the planned measurements were taken using the surgical navigator.

CONCLUSIONS

The endoscopic intraoral approach constitutes a feasible, safe and direct access route to the parapharyngeal space. This approach would be especially indicated in lesions of the parapharyngeal space (PPS) that do not exceed the styloid and pterygoid processes cranially, do not have significant retrostylial extension and do not substantially reach the lower area of the PPS.

Approaches to Parapharyngeal Space and Infratemporal Fossa Based on Different Anatomical Spaces

OBJECTIVES

The parapharyngeal space (PPS) and infratemporal fossa (ITF) present significant challenges for endoscopic skull base surgery due to their complex anatomy and lack of clear bony landmarks. This study aims to propose a systematic compartmentalization of the PPS and ITF, based on key anatomical structures, to optimize surgical planning and approaches.

METHODS

To retain a precise bony reference framework, the walls of the maxillary sinus and pterygoid bone were preserved. Anatomical dissection was conducted along muscular planes, dividing the region into 3 spaces. The feasibility and applicability of the proposed compartmentalization were evaluated through cadaveric studies and verified in clinical cases.

RESULTS

The PPS and ITF were classified into 3 distinct spaces based on the positioning and orientation of the medial pterygoid, lateral pterygoid, levator veli palatini, and stylopharyngeus muscles. The first space is located anterior to the pterygoid muscles, the second lies between the pterygoid muscles and the levator veli palatini/stylopharyngeus, and the third is posterior to these latter muscles. Among 24 clinical cases reviewed, 3, 8, and 13 lesions were situated in the first, second, and third spaces, respectively. Surgical outcomes were favorable, with complete lesion resection and no intraoperative or postoperative complications observed.

CONCLUSIONS

A three-space model of the PPS and ITF, defined by specific muscle planes, provides a structured framework to guide endoscopic skull base approaches. This model allows for targeted selection of surgical routes based on lesion location and its relationship with the internal carotid artery, aiming to minimize procedural risks.

[Overview and prospects of endoscopic skull base surgery]

Endoscopic skull base surgery presents significant technical challenges and high surgical risks, requiring collaboration among multiple disciplines such as otolaryngology, neurosurgery, ophthalmology, and oral maxillofacial surgery. In recent years, there has been rapid development in endoscopic skull base surgery, characterized by flourishing anatomical research and an expanding range of surgical indications. The future brings both opportunities and challenges, and endoscopic skull base surgery must grasp new directions in medical development, actively providing patients with safer and more effective treatment options.

[Research progress in the anatomy and surgical approach of the parapharyngeal space]

The parapharyngeal space, a complex fascial compartment within the head and neck region, encompasses crucial anatomical structures including blood vessels and nerves. Tumors occurring within this space are rare, with the majority being benign in nature. Surgical intervention remains the primary treatment modality; however, managing parapharyngeal space tumors poses significant challenges due to their intricate anatomical configuration. Conventional open surgical approaches have been associated with significant tissue damage and a high prevalence of postoperative complications. Recently, advancements in anatomical studies and surgical techniques have led to significant progress in understanding parapharyngeal space anatomy and improving surgical management. This article aims to provide a comprehensive overview of these developments.

[An anatomical road map of the parapharyngeal internal carotid artery in lateral and endoscopic ventral approaches]

Objective:To describe the road map of the lateral and endoscopic ventral approaches for the pharyngeal segment of the internal carotid artery, propose a sub-segmentation scheme, systematically and comprehensively understand its anatomical details and relationships with the surrounding structures. Methods:Five fresh cadaveric head specimens（10 sides in total） were dissected through lateral and endoscopic ventral approaches to evaluate the anatomical details of the parapharyngeal internal carotid artery and its relationship with the surrounding structures. Results:From the bifurcation of the common carotid artery to the vertical part of the internal carotid artery, alongside the direction of blood flow, the parapharyngeal internal carotid artery passes through four distinct anatomical tissues. Based on this, the parapharyngeal internal carotid artery can be divided into four sub-segments: nerve, muscle, fascia and osseous sub-segments. The boundaries and important adjacent structures of each segment are described in detail. Conclusion:The anatomical road map of the parapharyngeal internal carotid artery and the sub-segmentation scheme serving as a practical guide to navigate modular endoscopic skull base surgery of the parapharyngeal space while reduce the risk of internal carotid artery injury.

Anatomical studies and early results on endoscopic transoral medial pterygomandibular fold approach to salvage retropharyngeal lymphadenectomy in nasopharyngeal carcinoma

OBJECTIVE

Retropharyngeal lymphadenectomy is challenging. This study investigated a minimally invasive approach to salvage retropharyngeal lymphadenectomy in patients with nasopharyngeal carcinoma.

METHODS

An anatomical study of four fresh cadaveric heads was conducted to demonstrate the relevant details of retropharyngeal lymphadenectomy using the endoscopic transoral medial pterygomandibular fold approach. Six patients with nasopharyngeal cancer with retropharyngeal lymph node recurrence, who underwent retropharyngeal lymphadenectomy with the endoscopic transoral medial pterygomandibular fold technique at the Eye and ENT Hospital of Fudan University from July to December 2021, were included in this study.

RESULTS

The anatomical study demonstrated that the endoscopic transoral medial pterygomandibular fold approach offers a short path and minimally invasive approach to the retropharyngeal space. The surgical procedure was well tolerated by all patients, with no significant post-operative complications.

CONCLUSION

The endoscopic transoral medial pterygomandibular fold approach is safe and efficient for retropharyngeal lymphadenectomy.

[Advances in clinical anatomy of the transnasal approaches to the parapharyngeal segment of the internal carotid artery]

The intracranial segment of the internal carotid artery located inside the skeleton structure of skull base or inside the skull has clear anatomical landmarks and fixed anatomical structure. However, the parapharyngeal segment of the internal carotid artery located outside the cranial is surrounded by soft tissues, lacks clear and recognizable anatomical landmarks and sometimes has anatomical variation, which is closely related to transnasal endoscopic surgery. Intraoperative accidental injury can lead to serious complications or even death. Currently, clinical anatomical studies related to the parapharyngeal segment of the internal carotid artery under transnasal endoscopic surgery mainly focus on its anatomical variation and anatomical landmarks. This article reviews on these two aspects in order to provide anatomical reference for surgeons to reduce surgical risks during transnasal endoscopic surgery.

Endoscopic endonasal combined transoral medial approach to the nasopharynx, parapharyngeal space, and jugular foramen

OBJECTIVE

This study aimed to validate the feasibility of an endoscopic endonasal combined transoral medial approach for treating lesions in the nasopharynx, parapharyngeal space (PPS), and jugular foramen.

METHODS

Anatomical and imaging information of six patients who underwent surgery via this approach were reviewed and analyzed.

RESULTS

The feasibility and advantages of the endoscopic endonasal combined transoral medial approach, which uses an inside-to-outside medial surgical corridor, were identified. Total resection was achieved in 3 cases with benign tumors. Safe resection margins were obtained in 2 cases with recurrent nasopharyngeal carcinoma (NPC). Pathological biopsy of NPC lesion between the Eustachian tube and arterial sheath was achieved. The internal carotid artery (ICA) was accurately located and protected in all cases and no complications occurred.

CONCLUSION

Lesions in the nasopharynx, PPS, and jugular foramen can be directly assessed via this approach. The ICA can be well identified during the surgery.

Anatomical Variations of the Ascending Pharyngeal Artery: Implications for Endoscopic Surgery in the Parapharyngeal Space

Objectives: The ascending pharyngeal artery (APA) travels with the parapharyngeal internal carotid artery (pICA) in the parapharyngeal space (PPS). This study aimed to investigate the anatomical variations of the APA, and to explore their implications for endoscopic surgery in the PPS. Methods: Dissection of the APA in the PPS was performed on 10 cadaveric specimens (20 sides). The relationship between APA and PPS tumors was retrospectively reviewed in 20 patients, attempting to ascertain the APA during the resection of 10 pre-styloid and 10 retro-styloid PPS tumors. Results: During the cadaveric dissections, the APA was identified at the medial, posteromedial, or bilateral aspects of the pICA in 12 (60%) and 4 (20%) sides, respectively. In the remaining 4 sides (20%), the APA branched into several subcategory arteries lying at the medial and lateral aspects of the pICA. Branches of the APA were observed in 13/20 sides (65%). Two branches were found in 9/13 sides and 3 branches in 4/13, respectively. The APA was only identifiable in 1/10 (10%) of pre-styloid tumors, a patient with basal cell adenoma. In contrast, the APA was encountered surrounding the pICA in 8/10 (80%) of patients with retro-styloid tumors, all of which were schwannomas. No inadvertent injury of the APA or the pICA occurred in this cohort. Conclusions: With identification of the ascending pharyngeal artery on preoperative magnetic resonance imaging, it may serve as an additional landmark during the endoscopic extirpation of tumors arising in the PPS.

Parapharyngeal Space Ganglioneuroma: Clinical Experience and Review of the Literature

Ganglioneuroma is a rare benign tumor originating in the sympathetic ganglia, composed of differentiated ganglion cells, nerve sheath cells, and nerve fibers, which tend to occur in the posterior mediastinum, adrenal gland, retroperitoneal, and other locations, occurring in the head and neck is relatively rare, and parapharyngeal space involvement is extremely rare. In our report, we present 2 adult male patients whose preoperative imaging and fine needle cytology did not confirm the diagnosis of a parapharyngeal space mass and who completely resected the tumor through a combined cervical and oral approach. Finally, pathology confirmed ganglioneuroma; we also reviewed the English articles on parapharyngeal ganglioneuroma over the past 40 years, and summarized the diagnostic and treatment characteristics of parapharyngeal ganglioneuroma in combination with our cases to improve understanding of the disease.

Transoral Approach to Parapharyngeal Space Tumours: Preliminary Reports from a Single-Centre Retrospective Analysis

Purpose: The aim of this study is to identify certain parapharyngeal space tumours with specific characteristics that can be treated successfully through an endoscopically assisted transoral approach (EATA). Methods: Nine patients with PPS tumours underwent surgery through an EATA between 2003 and 2021. All patients underwent clinical examination and fibrolaryngoscopy. Preoperative CT and/or MRI was performed on all patients. Results: All the patients were successfully treated through an endoscopically assisted transoral approach. Histological examination revealed five pleomorphic adenomas, two schwannomas, one ectopic thyroid gland and one lipoma. The only long-term sequelae observed was Horner syndrome in the two schwannomas arising from the carotid space. The mean hospitalisation time was 2.6 days, while the mean follow-up time was of 9.7 years. Conclusions: An endoscopically assisted transoral approach (EATA) is a valid technique for treating benign capsulated tumours of the true PPS and some benign capsulated tumours of the superomedial aspect of the carotid space.

Maximal exposure of the parapharyngeal internal carotid artery via transnasal and transoral corridors

BACKGROUND

The parapharyngeal internal carotid artery (pICA) could be surgically exposed through the transnasal and transoral corridors. However, their potential degree of exposure has not been established sufficiently. This study aims to elucidate the maximal exposure of the pICA via the transnasal and transoral corridors.

METHODS

An endonasal transpterygoid nasopharyngectomy for exposure of the pICA was performed on eight cadaveric specimens (16 sides), while a transoral approach for exposure of the pICA was performed on six additional specimens (12 sides). In addition, the CT angiography of 60 consecutive patients (120 sides) was analyzed to establish the potential maximal exposure of the pICA through each corridor.

RESULTS

The hard palate becomes a restricting factor for the inferior exposure of the pICA via the transnasal approach, whereas the entire pICA segment could be adequately displayed through the transoral corridor. The maximal exposed length of the pICA for a transnasal and transoral approach was 3.08 ± 0.30 cm and 6.56 ± 0.57 cm, respectively. This difference was statistically significant (p < 0.001).

CONCLUSION

An endonasal exposure of the pICA seems limited to its superior aspect, whereas the transoral corridor could provide adequate exposure of the entire length of pICA.

Endoscopic transoral approach to the lateral poststyloid space

The lateral poststyloid space (LPSS) located at the posterolateral aspect of the styloid process. This study aims to explore the anatomical relationships in LPSS via a transoral corridor, providing reference for addressing lesions extending to this region. An endoscopic transoral approach for exposure of the LPSS was performed on 6 cadaveric specimens (12 sides). Related landmarks were explored, and transoral extirpation of tumors extended into LPSS was employed in 12 patients. The deep lobe of the parotid gland, extratemporal facial nerve, and the accompanying artery in the LPSS were sufficiently exposed via the transoral corridor in all 12 cadaveric sides. The transoral corridor provided adequate exposure for tumors extending to the LPSS, and en bloc resection was achieved in these 12 patients. No facial nerve or vascular injury occurred, and no recurrence observed in this cohort with an average follow-up of 26 months. An endoscopic transoral approach provides a direct access to the LPSS. Appreciation of the anatomical relationships within the LPSS is valuable for employing a transoral extirpation of tumors extending to this specific region.

Endoscopic trans-lateral oropharyngeal wall approach to the petrous apex and the petroclival region

BACKGROUND

A trans-lateral oropharyngeal wall approach (TLOWA) to the petrous apex has not been previously defined. This study aims to assess the feasibility of a TLOWA for surgical access to the petrous apex and the petroclival region.

METHODS

An endoscopic TLOWA for exposure of the petrous apex and petroclival region was performed on five cadaveric specimens (10 sides). Associated anatomical landmarks were defined, and the strategies for maximal exposure of the internal carotid artery (ICA) were explored.

RESULTS

Via a TLOWA, the parapharyngeal ICA was widely exposed in all 10 sides. Following transection of the Eustachian tube, the inferior petrous apex and petroclival region could be sufficiently exposed. After drilling the anteroinferior bony canal, the horizontal petrous ICA, foramen lacerum, and the paraclival ICA could be adequately revealed.

CONCLUSION

The TLOWA may provide an alternative corridor for access to the petrous apex and the petroclival region. The parapharyngeal, petrous, lower paraclival ICAs, and the foramen lacerum could be adequately exposed via the TLOWA.

Exploration of anatomical landmarks for performing an endoscopic transoral nasopharyngectomy

BACKGROUND

Performing a nasopharyngectomy via a transoral approach has been reported; however, defining landmarks to facilitate this approach has not been addressed. This study aims to explore anatomical landmarks to aid in performing a nasopharyngectomy via the transoral corridor.

METHODS

An endoscopic transoral nasopharyngectomy was performed on six cadaveric specimens (12 sides). Related anatomical landmarks were defined, and the strategy to preserve the parapharyngeal internal carotid artery (pICA) was explored.

RESULTS

An endoscopic transoral nasopharyngectomy was successfully achieved in all 12 sides. Utilizing the pterygoid hamulus as a landmark, the cartilaginous ET and attachments could be adequately exposed. Identification of the pICA is a prerequisite prior to Eustachian tube (ET) transection. The sphenoidal spine and the petrotympanic fissure could be sufficiently revealed in all 12 sides, which aided in transection of the cartilaginous ET without pICA injury. The ET and the prevertebral contents could be adequately removed via the transoral corridor.

CONCLUSION

The pterygoid hamulus, sphenoidal spine and petrotympanic fissure serve as reliable landmarks for performing a transoral nasopharyngectomy. Identification of the pICA is a prerequisite prior to transection of the ET to avoid pICA injury.

Endoscopic transoral approach to the parapharyngeal space: technical nuances and preliminary results

OBJECTIVE

Surgical management is the mainstay of treatment for tumours in the parapharyngeal space. This study aimed to evaluate the indications, limits and technical nuances of the endoscopic transoral approach.

METHOD

Thirteen patients with parapharyngeal space tumours that were treated between May 2017 and November 2020 were included in this retrospective study.

RESULTS

All patients underwent surgery for complete oncological resection except one patient who received treatment for diagnostic purposes. No major complications were reported, with excellent control of the vital structures of the parapharyngeal space.

CONCLUSION

The endoscopic transoral approach to the parapharyngeal space is a promising alternative approach for selected parapharyngeal space tumours with satisfactory outcomes.

Keyhole Endoscopic-Assisted Transcervical Approach to the Upper and Middle Retrostyloid Parapharyngeal Space: An Anatomic Feasibility Study

Objectives The aim of this study was to describe the anatomical nuances, feasibility, limitations, and surgical exposure of the parapharyngeal space (PPS) through a novel minimally invasive keyhole endoscopic-assisted transcervical approach (MIKET).

Design Descriptive cadaveric study.

Setting Microscopic and endoscopic high-quality images were taken comparing the MIKET approach with a conventional combined transmastoid infralabyrinthine transcervical approach.

Participants Five colored latex-injected specimens (10 sides).

Main Outcome Measures Qualitative anatomical descriptions in four surgical stages; quantitative and semiquantitative evaluation of relevant landmarks.

Results A 5 cm long inverted hockey stick incision was designed to access a corridor posterior to the parotid gland after independent mobilization of nuchal and cervical muscles to expose the retrostyloid PPS. The digastric branch of the facial nerve, which runs 16.5 mm over the anteromedial part of the posterior belly of the digastric muscle before piercing the parotid fascia, was used as a landmark to identify the main trunk of the facial nerve. MIKET corridor was superior to the crossing of the accessory nerve over the internal jugular vein within 17.3 mm from the jugular process. Further exposure of the occipital condyle, vertebral artery, and the jugular bulb was achieved.

Conclusion The novel MIKET approach provides in the cadaver straightforward access to the upper and middle retrostyloid PPS through a natural corridor without injuring important neurovascular structures. Our work sets the anatomical nuances and limitations that should guide future clinical studies to prove its efficacy and safety either as a stand-alone procedure or as an adjunct to other approaches, such as the endonasal endoscopic approach.

[Endoscopic transoral retropharyngeal lymphadenectomy]

Objective:The aim of this study is to explore the anatomy and surgical approach of retropharyngeal lymphadenectomy via endoscopic transoral approach. Methods:The retropharyngeal spaces were studied with three fresh frozen cadaver head （6 sides） in the anatomical laboratory of Eye, Ear, Nose and Throat Hospital of Fudan University through endoscopic transoral approach. The superior pharyngeal constrictor muscle, medial pterygoid muscle, tendon of tensor veli palatini muscle, fat of prestyloid space, ascending palatine artery and its branches, styloglossus, stylopharyngeus, stylohyoideus, external carotid artery, levator veli palatini, carotid sheath, ascending pharyngeal artery and longus capitis muscle were revealed in order. The above-mentioned structures were photographed with a 0° Karl Storz nasal endoscope and adjacent relationships were recorded. A case of metastatic retropharyngeal lymphadenopathy was reviewed and the surgical methods and techniques of retropharyngeal lymphadenectomy via endoscopic transoral approach were introduced in detail. Results:The retropharyngeal space and related anatomical structures were exposed through endoscopic transoral approach in all specimens. The styloglossus, stylopharyngius and levator veli palatini are the markers of locating the internal carotid artery. The superior pharyngeal constrictor muscle, medial pterygoid muscle, styloid muscle group, longus capitis muscle and carotid sheath are the markers that can be used to locate the retropharyngeal lymph nodes. Ascending palatine artery, ascending pharyngeal artery and internal carotid artery are the main arteries involved in retropharyngeal lymphadenectomy via endoscopic transoral approach. Conclusion:Endoscopic transoral approach is a new surgical technique to perform retropharyngeal lymphadenectomy safely and completely.

[Research advances on endoscopic surgical approach for infratemporal fossa tumors]

The tumors occurring in infratemporal fossa （ITF） and parapharyngeal space account for 0.5%-1.0% of head and neck tumors, 80% of which are benign and 20% are malignant. At present, a variety of ITF surgical approaches have been described in domestic and foreign literatures. However, the selection of surgical approaches in clinical practice is still based on the habits and experience of the operators, there is still a lack of standardized clinical guidance. This article mainly introduces the advantages and disadvantages of the latest anatomical division of ITF and the corresponding endoscopic surgical approach as well as the research progress, so as to provide reference for the selection of the optimal surgical approach for ITF tumors.

Endonasal access to lower cranial nerves: From foramina to upper parapharyngeal space

Lesions arising from the upper parapharyngeal space (UPPS) often involved the jugular foramen region (JFR), occasionally extending into the posterior cranial fossa. This study aims to investigate the surgical anatomy of the JFR and UPPS from the perspective of an expanded endoscopic approach (EEA), tracing the lower cranial nerves from their extracranial foramina to the UPPS. Six cadaveric specimens (12 sides) underwent a transpterygoid EEA to expose the JFR and UPPS. Distances from the medial pterygoid plate (MPP) to the internal carotid artery (ICA), hypoglossal canal (HC), and jugular tubercle (JT) were measured on anonymized Computed tomography angiography images previously obtained from 30 patients with pulsatile tinnitus. Full access to the JFR, and its medial, superior, and anterior aspects, could be adequately achieved via an EEA. Upon exiting the jugular foramen, the glossopharyngeal nerve courses posterior to the ICA, traveling inferiorly into the UPPS between ICA and IJV. The vagus nerve is in close proximity to the hypoglossal nerve traveling posterior to the ICA. The accessory nerve courses lateral to the vagus nerve, running posterior to the IJV. The minimal distances from the MPP to ICA, HC, and JT were 2.52 ± 0.34, 2.86 ± 0.36, and 3.18 ± 0.33 cm, respectively. This anatomical study strongly suggests the feasibility of using an EEA to access to the medial, superior, and anterior aspects of the jugular foramen and the adjacent UPPS.

Transoral Excision of Parapharyngeal Space Tumors

Transoral excision of parapharyngeal space (PPS) tumors has increased in popularity along with the increased use of robotic and endoscopic surgical technology. Here, the authors highlight the indications, techniques, outcomes, and complications of transoral approaches to PPS tumors, with a special emphasis on salivary tumors of the PPS and the transoral robotic surgery approach.

Transinfratemporal Fossa Transposition of the Temporalis Muscle Flap for Skull Base Reconstruction after Endoscopic Expanded Nasopharyngectomy: Anatomical Study and Clinical Application

Objective Temporalis muscle flap (TMF) is widely used in traditional skull base surgery, but its application in endoscopic skull base surgery remains rarely reported. We aimed to investigate the surgical anatomy and clinical application of TMF for reconstruction of skull base defects after expanded endoscopic nasopharyngectomy.

Methods Nine fresh cadaver heads (18 sides) were used for endoscopic dissection at the University of Pittsburgh School of Medicine in the United States. TMF was harvested using a traditional open approach and then transposed into the maxillary sinus and nasal cavity through the infratemporal fossa using an endoscopic transnasal transmaxillary approach. TMF length was then measured. Moreover, TMF was used for the reconstruction of skull base defects of six patients with recurrent nasopharyngeal carcinoma after expanded endoscopic nasopharyngectomy.

Results The length of TMF harvested from the temporal line to the tip of the coronoid process of the mandible was 11.8 ± 0.9 cm. The widest part of the flap was 9.0 ± 0.4 cm. When TMF was dislocated from the coronoid process of the mandible, approximately another 2 cm of reach could be obtained. When the superficial layer of the temporalis muscle was split from the deep layer, the pedicle length could be extended 1.9 ± 0.2 cm. TMF could cover skull base defects in the anterior skull base, sellar, and clivus regions.

Conclusion TMF can be used to reconstruct skull base defects after endoscopic expanded nasopharyngectomy and can effectively prevent the occurrence of serious complications in patients with recurrent nasopharyngeal carcinoma.

Endoscopy-Assisted Transoral Approach to Resect Parapharyngeal Space Tumors: A Systematic Review and Meta-Analysis

OBJECTIVES

By comparing the endoscopy-assisted transoral approach (EATA) with external approaches (EAs) for the resection of parapharyngeal space tumors (PPSTs), we determined whether the EATA has advantages in terms of operation time, intraoperative bleeding volume, postoperative hospitalization, drainage volume, and complications. At the same time, we summarized the surgical indications for the EATA.

METHODS

Systematic literature retrieval was performed in the PubMed, Web of Science, Embase, CNKI, Wanfang, and CQVIP databases up to February 2020. We calculated the mean difference (MD) with a 95% confidence interval (CI) for continuous outcomes and pooled odds ratio (OR) with 95% CI for dichotomous outcomes. The measured outcomes were operative time, bleeding volume, postoperative hospitalization, drainage volume, and complications.

RESULTS

Seven studies involving 318 patients were eligible. Of these patients, 145 patients underwent EATA and 173 patients underwent EA surgery. All the former tumors were benign and located medial or anteromedial to the carotid sheath except for the unrecorded tumors. Compared with EAs, the EATA significantly shortened the operation time (MD = -5.56 min, 95% CI: -9.58 to -1.55), shrank the bleeding volume (MD = -89.02 ml, 95% CI: -126.16 to -51.88), shortened the postoperative hospitalization (MD = -2.44 days, 95% CI: -3.37 to -1.51), reduced the drainage volume (MD = -32.97 ml, 95% CI: -36.24 to -29.70), and lowered the incidence of complications (OR = 0.30, 95% CI: 0.16 to 0.59).

CONCLUSION

As for PPSTs, with an appropriate and precise patient selection, the EATA is a safe, effective, minimally invasive, and aesthetic surgical modality. Laryngoscope, 2021.

Free tissue transfer for central skull base defect reconstruction: Case series and surgical technique

OBJECTIVES

Local reconstruction of central skull base defects may be inadequate for large defects or reoperative cases; free tissue transfer may be necessary. Inset of the flap and management of the pedicle can be challenging. We report our experience and approaches.

METHODS

Retrospective review identifying seven patients with central skull base defects who underwent free flap reconstruction from 2016 to 2020.

RESULTS

Four patients with recurrent nasopharyngeal carcinoma, one with recurrent craniopharyngioma, one with clival-cervical chordoma, and one with meningioma of the middle cranial fossa were analyzed. Six defects were closed with an anterolateral thigh free flap and one with a radial forearm free flap. In two patients, the flap was secured in an onlay fashion to the defect via a Caldwell-Luc transmaxillary approach. In one patient, the flap was passed transorally, and the pedicle was delivered into the neck via Penrose drain. In two patients, a parapharyngeal technique and in two others, a retropharyngeal was used for nasopharyngeal inset with endoscopic assistance. There were no flap failures, with an average follow-up time of 20.1 (range 3.2-47.1) months. One patient required flap repositioning on postoperative day three due to midline shift and intracranial contents compression. The transoral inset flap necessitated flap repositioning on postoperative day 13 to improve the nasopharyngeal airway.

CONCLUSION

Free flap reconstruction of the central skull base is challenging, but transmaxillary, transoral, parapharyngeal, and retropharyngeal approaches can be used with endoscopic assistance to ensure secure inset flap and avoid airway obstruction.

Types of Transnasal Endoscopic Nasopharyngectomy for Recurrent Nasopharyngeal Carcinoma: Shanghai EENT Hospital Experience

Background

Transnasal endoscopic nasopharyngectomy (TEN) has become increasingly used for recurrent nasopharyngeal carcinoma (rNPC); however, there is no report on the definitive resectable contour for TEN according to the latest staging system for nasopharyngeal carcinoma. The aim of this study was to establish the types of TEN for rNPC.

Materials and Methods

A total of 101 rNPC patients underwent TEN from January 2016 to April 2019 at the authors’ institution. TEN was categorized into four types, which included type I (n=40) with resection of the nasopharynx and sinuses; type II (n=10) with lateral extension to the parapharyngeal space; type III (n=40) with lateral extension to the floor of the middle cranial fossa and the infratemporal fossa and superior extension to the orbital apex and the cavernous sinus back to the prevertebral region; and type IV (n=11) with the resection of the involved internal carotid artery following type III. The 2-year overall survival rate (OS) and local recurrence-free survival rate (LRFS) were assessed.

Results

The median time of follow-up was 20 months. Twenty-five patients reoccurred. Nineteen patients died. Independent predictors of outcome on multivariate analysis were recurrent T stage (P = 0.039), types of TEN (P = 0.002) and surgical margin (P = 0.003). The 2-year OS and LRFS was 76.2% and 53.6%, respectively.

Conclusions

The result of TEN in the treatment of rNPC is promising. The types of TEN will provide effective guideline for surgical treatment of rNPC.

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.

Endoscopic transnasal transmaxillary approach to the upper parapharyngeal space and the skull base

PURPOSE

Treatment of tumors arising in the upper parapharyngeal space (PPS) or the floor of the middle cranial fossa is challenging. This study aims to present anatomical landmarks for a combined endoscopic transnasal and anterior transmaxillary approach to the upper PPS and the floor of the middle cranial fossa and to further evaluate their clinical application.

METHODS

Dissection of the upper PPS using a combined endoscopic endonasal transpterygoid and anterior transmaxillary approach was performed in six cadaveric heads. Surgical landmarks associated with the approach were defined. The defined approach was applied in patients with tumors involving the upper PPS.

RESULTS

The medial pterygoid muscle, tensor veli palatini muscle and levator veli palatini muscle were key landmarks of the approach into the upper PPS. The lateral pterygoid plate, foramen ovale and mandibular nerve were important anatomical landmarks for exposing the parapharyngeal segment of the internal carotid artery through a combined endoscopic transnasal and anterior transmaxillary approach. The combined approach provided a better view of the upper PPS and middle skull base, allowing for effective bimanual techniques and bleeding control. Application of the anterior transmaxillary approach also provided a better view of the inferior limits of the upper PPS and facilitated control of the internal carotid artery.

CONCLUSIONS

Improving the knowledge of the endoscopic anatomy of the upper PPS allowed us to achieve an optimal approach to tumors arising in the upper PPS. The combined endoscopic transnasal and anterior transmaxillary approach is a minimally invasive alternative approach to the upper PPS.

Preauricular retromandibular trans tympanic plate and styloid process keyhole approach to parapharyngeal lesions: a laboratory study

BACKGROUND

The surgical removal of the infratemporal parapharyngeal lesions (IPL) is challenging due to its anatomical complexity. Previous surgical approaches have often been too invasive and necessitated sacrifice of normal function and anatomical structures, particularly in the retromandibular nerve region. Therefore, we sought to identify an approach corridor to this area that requires less sacrifice and report an innovative approach through a retromandibular fossa route to the IPL.

METHODS

Five cadaveric specimens were dissected bilaterally with a trans-tympanic plate and styloid process approach. These specimens were investigated microanatomically and morphometrically to examine the extent of the approach in the parapharyngeal space. The clinical application of this approach was compared to previous approaches to the IPL used in our clinical series of 20 cases.

RESULTS

Using this novel approach, the inferior alveolar nerve was identified in all specimens, while the chorda tympani and lingual nerve were identified in 6 (60%) and 4 (40%) dissections, respectively. In all specimens, the petrous portion of the internal carotid artery and the exit of the lower cranial nerve were identified. The average length of the exposed lower cranial nerves was 16.6 ± 3.8 mm (range: 11-25 mm).

CONCLUSIONS

The described approach is feasible for accessing the IPL at the retromandibular nerve and is less invasive than conventionally used approaches.

A minimally invasive endoscopic transnasal retropterygoid approach to the upper parapharyngeal space: anatomic studies and surgical implications

BACKGROUND

Surgery remains the mainstay of treatment for lesions in the parapharyngeal space. However, gaining access to the parapharyngeal space is often challenging. In this study we aim to describe a minimally invasive technique of approaching the upper parapharyngeal space through an endoscopic transnasal retropterygoid approach, based on anatomic studies and surgeries.

METHODS

Six fresh human cadaver heads were prepared for anatomic study at the Surgical Neuroanatomy Laboratory of the Center for Cranial Base Surgery within the Department of Neurological Surgery at the University of Pittsburgh School of Medicine. Three clinical cases seen in the Department of Otolaryngology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College of Fudan University, were used to illustrate the technique and feasibility of this approach and to assess its indications, advantages, and drawbacks.

RESULTS

The medial pterygoid plate is the primary landmark of the endoscopic transnasal retropterygoid approach to the upper parapharyngeal space. Access to the upper parapharyngeal space could be obtained by removing the mucosa on the medial pterygoid plate and the mucosa below the pharyngeal orifice of the Eustachian tube. The 3 patients in our study tolerated the procedure well and had no serious complications after surgery.

CONCLUSION

The anatomic data and clinical cases in this study confirm that an endoscopic transnasal retropterygoid approach is a feasible and effective surgical treatment for selected tumors in the upper parapharyngeal space.

The anatomy of the parapharyngeal segment of the internal carotid artery for endoscopic endonasal approach

Injury to the internal carotid artery (ICA) is a life-threatening complication of endoscopic endonasal approaches. The objective of this study is to illustrate the detail anatomy of the parapharyngeal segment of the ICA (PPICA) to safe endoscopic endonasal surgery. The anatomical dissection was performed in 10 cadaveric specimens and several crucial anatomical landmarks were identified and measured. In addition, 50 dry skulls were studied to further assess the relationship between the pharyngeal tubercle and carotid foramen. From the endoscopic endonasal perspective, in the median plane, the pharyngeal tubercle and the carotid foramen on both sides were located on a line. The average distance between the pharyngeal tubercle and anterior border of the external orifice of the carotid canal was measured as 25.2 ± 3.2 mm. In the paramedian plane, the PPICA was located between the levator veli palatini muscle (LVPM) and the stylopharyngeal muscle (SPM) in upper parapharyngeal space in all specimens, and the distance from the posterior border of the LVPM to the anterior border of the SPM was recorded as 15.1 ± 2.8 mm at the level of the carotid foramen. The distance from the attachment of the LVPM to the anterior border of the external orifice of the carotid canal was about 5.1 ± 0.2 mm. The fully developed stylopharyngeal fascia (SPhF) was observed in 10 cases, and the PPICA was always anteriorly enclosed by and adhered to the SPhF.

Review of the main surgical and angiographic-oriented classifications of the course of the internal carotid artery through a novel interactive 3D model

The course of the internal carotid artery (ICA) and its segment classifications were reviewed by means of a new and freely available 3D interactive model of the artery and the skull base, based on human neuroimages, that can be freely downloaded at the Public Repository of the University of Barcelona (http://diposit.ub.edu/dspace/handle/2445/112442) and runs under Acrobat Reader in Mac and Windows computers and Windows 10 tablets. The 3D-PDF allows zoom, rotation, selective visualization of structures, and a predefined sequence view. Illustrative images of the different classifications were obtained. Fischer (Zentralbl Neurochir 3:300-313, 1938) described five segments in the opposite direction to the blood flow. Gibo-Rothon (J Neurosurg 55:560-574, 1981) follow the blood flow, incorporated the cervical and petrous portions, and divided the subarachnoid course-supraclinoid-in ophthalmic, communicating, and choroidal segments, enhancing transcranial microscopic approaches. Bouthillier (Neurosurgery 38:425-433, 1996) divided the petrous portion describing the lacerum segment (exposed in transfacial procedures and exploration of Meckel's cave) and added the clinoid segment between the proximal and distal dural rings, of interest in cavernous sinus surgery. The Kassam's group (2014), with an endoscopic endonasal perspective, introduces the "paraclival segment," including the "lacerum segment" and part of the intracavernous ICA, and details surgical landmarks to minimize the risk of injury. Other classifications are also analyzed. This review through an interactive 3D tool provides virtual views of the ICA and becomes an innovative perspective to the segment classifications and neuroanatomy of the ICA and surrounding structures.