Endoscopic endonasal nasopharyngectomy: tensor veli palatine muscle as a landmark for the parapharyngeal internal carotid artery

Endoscopic endonasal transpterygoid nasopharyngectomy: Anatomical considerations and technical note

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Surgical Landmarks for Parapharyngeal Internal Carotid Artery During Extended Endoscopic Surgery of Nasopharynx: A Cadaveric and Radiological Study

Nasopharynx is a complex region situated at the center of skull surrounded by various vital neurovascular structures. Surgical access to the nasopharyngeal space poses significant challenges due to the position of the internal carotid artery (ICA). Open approaches to nasopharynx utilize the lateral to medial anatomy but the endoscopic endo-nasal approach warrants knowledge about the medial to lateral anatomy. In this study we attempted to find the consistent surgical landmarks for parapharyngeal portion of internal carotid artery at the level of nasopharynx by means of cadaveric and radiological study. Eight fresh frozen cadavers (16 sides) and 30 CT angiography (60 sides) were included in the anatomical and radiological study respectively. Superior aspect of the torus tubarius was taken as the reference point in cadaveric study and C1-C2 interspace was used as the reference point for the radiological study. The distance between the ICA to the landmarks such as fossa of Rosenmullaer, torus tubarius, medial and lateral pterygoid plates were recorded. The mean distance of ICA to the fossa of Rosenmuller was 8.5 ± 1.4 mm and 9.1 ± 1.1 mm in the cadaveric and radiological study respectively. The mean distance between ICA to torus tubarius was 19.8 ± 1.3 mm in cadaveric and 20.6 ± 1.0 mm in radiological study. The mean distance of ICA to medial and lateral pterygoid plates were 25.3 ± 1.4 mm and 18.2 ± 1.4 mm in the cadaveric study and 25.9 ± 1.2 mm and 18.8 ± 1.3 mm in the radiological study respectively. On correlating the measurements between cadaveric and radiological study, the p values were not statistically significant (p > 0.05). The closest landmark to the ICA was the fossa of Rosenmuller. ICA was located at the same sagittal plane as that of the lateral pterygoid plate. The nasopharynx is a complex anatomical region closely related to ICA. Inadvertent injury to ICA is one of the dreaded complications of nasopharyngeal surgery. Fossa of Rosenmuller is only few millimeters away from the ICA and must be treated very cautiously. During the endoscopic approach, the ICA is at the sagittal plane as of the lateral pterygoid plate. This must be kept in mind when advancing toward the ICA by keeping intact the lateral pterygoid plate when possible and one should stay in the plane of medial pterygoid plate as the ICA lies posterolateral to it. Cadaveric dissections supported by radiological data would definitely aid surgeons to successfully perform surgeries in nasopharynx.

Endonasal Exposure of Lateral Recess of the Sphenoid Sinus: Significance of Pterygoid Process Pneumatization

Background

Caudal pneumatization of the pterygoid process may impact endonasal exposure of the lateral recess of sphenoid sinus (LRSS).

Objectives

This study aims to explore the implications of a pneumatized pterygoid process for an endonasal transpterygoid approach to the LRSS and to define strategies regarding the preservation or sacrifice of the vidian nerve.

Methods

Dissection of the LRSS (11 sides) was performed on 6 cadaveric specimens, preselected for the radiographic presence of an LRSS. In addition, the dimensions of the LRSS were measured on the deidentified CT images of 120 patients (240 sides). The sphenoid sinus was subdivided into 3 categories: Type 1 (no identifiable LRSS), Type 2 (lateral pneumatization of the greater wing above the vidian canal), and Type 3 (pneumatization of both the greater wing and the pterygoid process).

Results

On the cadaveric specimens, a Type 2 pneumatization often allowed access to the LRSS above the level of the vidian canal; thus, sparing the vidian neurovascular bundle. In Type 3 pneumatization, a frontal corridor through the pterygoid base could be created to reach the LRSS with preservation of the vidian nerve. Extreme Type 3 pneumatization, however, required the transposition or sacrifice of the vidian nerve to facilitate a full direct access to the superolateral LRSS. Measurements on CT images revealed that the extent of caudal pneumatization of the pterygoid process had no statistically significant correlation with the superolateral extension of the lateral recess in patients with Type 3 LRSS ( P > .05).

Conclusion

Pneumatization of the LRSS toward a caudal or superolateral direction may develop independent from each other. Caudal pneumatization of the pterygoid process seems to variably impact the endonasal exposure of the LRSS.

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.

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.

ICAR: endoscopic skull-base surgery

BACKGROUND

Endoscopic skull-base surgery (ESBS) is employed in the management of diverse skull-base pathologies. Paralleling the increased utilization of ESBS, the literature in this field has expanded rapidly. However, the rarity of these diseases, the inherent challenges of surgical studies, and the continued learning curve in ESBS have resulted in significant variability in the quality of the literature. To consolidate and critically appraise the available literature, experts in skull-base surgery have produced the International Consensus Statement on Endoscopic Skull-Base Surgery (ICAR:ESBS).

METHODS

Using previously described methodology, topics spanning the breadth of ESBS were identified and assigned a literature review, evidence-based review or evidence-based review with recommendations format. Subsequently, each topic was written and then reviewed by skull-base surgeons in both neurosurgery and otolaryngology. Following this iterative review process, the ICAR:ESBS document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:ESBS document addresses the role of ESBS in primary cerebrospinal fluid (CSF) rhinorrhea, intradural tumors, benign skull-base and orbital pathology, sinonasal malignancies, and clival lesions. Additionally, specific challenges in ESBS including endoscopic reconstruction and complication management were evaluated.

CONCLUSION

A critical review of the literature in ESBS demonstrates at least the equivalency of ESBS with alternative approaches in pathologies such as CSF rhinorrhea and pituitary adenoma as well as improved reconstructive techniques in reducing CSF leaks. Evidence-based recommendations are limited in other pathologies and these significant knowledge gaps call upon the skull-base community to embrace these opportunities and collaboratively address these shortcomings.

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.

An endoscopic anatomical study of the levator veli palatini and its relationship to the parapharyngeal internal carotid artery

BACKGROUND

The objectives of this study are to describe the levator veli palatini (LVP) as a landmark for the parapharyngeal internal carotid artery (pICA) and the endoscopic course of the pICA.

METHODS

Cadaver dissection and illustrative case study.

RESULTS

Seven cadaveric heads (12 sides) were dissected. In all 12 sides, the LVP was consistently located between the Eustachian tube and the pICA near the skull base, making the LVP just anterior to and the closest structure to the pICA. The distance between the pICA and the nares ranged from 9.0 to 12.7 cm. The distance between the pICA and the midpoint of the nasopharynx ranged from 1.9 to 3.7 cm. The case study illustrated the applicability of these findings.

CONCLUSION

The LVP is a reliable and precise landmark for the pICA. A safe working distance to the pICA is 1.9 cm from the midpoint of the nasopharynx and 9.0 cm from the nares.

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.