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.

[Endonasal repair of spontaneous CSF fistulas of the lateral recess of the sphenoid sinus]

CSF fistulas of the lateral recess of the sphenoid sinus are a rare surgical pathology. Cerebrospinal fluid leak from lateral recess of the sphenoid sinus is observed with a frequency of 7.7% among all leakafe of the skull base. The article presents 3 clinical cases of patients with spontaneous cerebrospinal fluid leak from lateral recess of the sphenoid sinus and surgical treatments by transsphenoidal and transpterygoid (transpterygoid) endoscopic approaches with various postoperative results. The plastic surgery success of CSF fistulas from lateral recess of the sphenoid sinus doesn`t depend on the type of endonasal surgical approach, but on the plastic quality and the preoperative level of CSF pressure.

Management of Cerebrospinal Fluid Rhinorrhea in the Sphenoid Sinus Lateral Recess Through an Endoscopic Endonasal Transpterygoid Approach With Obliteration of the Lateral Recess

BACKGROUND

Cerebrospinal fluid rhinorrhea in the sphenoid sinus lateral recess is a rare occurrence and poses unique challenges due to limited surgical access for surgical repair.

OBJECTIVE

To report our experience of surgical repair of cerebrospinal fluid rhinorrhea in the sphenoid sinus lateral recess through an endoscopic endonasal transpterygoid approach with obliteration of the lateral recess. To evaluate the efficiency of this surgical procedure.

METHODS

A retrospective study. Twelve cases with cerebrospinal fluid rhinorrhea in the sphenoid sinus lateral recess were reviewed. Assisted by image-guided navigation, cerebrospinal fluid rhinorrhea was repaired through an endoscopic endonasal transpterygoid approach, with obliteration of the lateral recess. Complications and recurrence were recorded. Medical photographs were used.

RESULTS

This surgical approach provided a relatively spacious corridor to dissect the sphenoid sinus lateral recess and do postoperative surveillance. The repair area completely healed in 3 months after surgery. Cerebrospinal fluid rhinorrhea in the sphenoid sinus lateral recess was successfully repaired on the first attempt in all cases (100%). No main complications or recurrence was observed during a mean follow-up time of 40.3 months.

CONCLUSION

The endoscopic endonasal transpterygoid approach gives appropriate access for the treatment of spontaneous cerebrospinal fluid rhinorrhea in the sphenoid sinus lateral recess. Multilayer reconstruction of a skull base defect with obliteration of the lateral recess is a reliable and simple method.

Modified Ipsilateral Endonasal Endoscopic Trans-Sphenoidal Approach to Sphenoid Sinus Lateral Recess Cerebrospinal Fluid Leak Management in Two Cases: A Technical Note

Background  Cerebrospinal fluid (CSF) leak from the sphenoid sinus lateral recess (SSLR) is very rare. Majority prefer transpterygoid approach which is extensive and time consuming. Two such cases were managed with least possible dissection/destruction of paranasal sinus. Methods  Two cases of SSLR were accessed through the ipsilateral nostril from the side of CSF leak. Wide ipsilateral anterior sphenoidotomy was done preserving intersinus septum of sphenoid sinus. Middle turbinate was lateralized and remaining paranasal structures were preserved. Two handed single nostril approach was done in both the cases by 45- and 70-degree endoscope along with angled instruments. SSLR defects were visualized and packed with autologous fat graft and glue. Results  SSLR defects could be visualized and packed with fat graft in both the cases from ipsilateral side. Both cases had uneventful outcome with no leak with mean -follow-up of 11.5 months. Conclusion  Modified ipsilateral endonasal endoscopy trans-sphenoidal approach is least invasive technique for SSLR leak. Use of angled scope and instruments help in defect visualization, avoiding extensive paranasal sinus dissection and bony removal. Tedious time-consuming reconstructive procedures can be avoided with simple fat graft with good outcome.

Endoscopic management of lateral sphenoid cerebrospinal fluid leaks: Identifying a radiographic parameter for surgical planning

OBJECTIVE

Repair of cerebrospinal fluid (CSF) leaks of the lateral recess of the sphenoid (LRS) sinus can be challenging to accomplish via an endoscopic transphenoidal approach. The endoscopic transpterygoid approach can improve surgical access to the lateral recess but requires more extensive surgical dissection. We review our experience with LRS CSF leak repair via both techniques to determine whether preoperative radiologic data can help predict the most appropriate surgical approach.

METHODS

Electronic medical records of patients with LRS CSF leaks were retrospectively reviewed at a single tertiary referral center. Radiographic measurements from preoperative computed tomography images were reviewed.

RESULTS

Twenty-two LRS CSF leaks were identified. The transphenoidal and transpterygoid approach were used in 6 (27.3%) and 16 (72.7%) cases, respectively.The mean vidian canal to foramen rotundum angle of the repairs accessed transphenoidally as compared to the transptyergoid approach were not significantly different (41.93° ±10.91, 40.72° ±19.49, respectively; P = .63). However, the mean volume of the LRS accessed by the transpterygoid approach was significantly greater compared to those accessed through the transphenoidal approach (0.97 cm3 ± 0.48, 0.39 cm3 ± 0.40, respectively; P = .04). A LRS volume of 0.400 cm3 or greater predicted the use of the transpterygoid approach with 93.3% sensitivity and 60.0% specificity.

CONCLUSION

This study demonstrated that LRS CSF leaks that necessitated repair by the transpterygoid approach, rather than transphenoidal approach, were in the context of significantly larger lateral recess. Assessment of the LRS volume is a quantifiable parameter to aid in preoperative surgical planning.

LEVEL OF EVIDENCE

Level 4.

Cerebrospinal fluid rhinorrhea from the lateral recess of sphenoid sinus: More to it than meets the eye

Background

Cerebrospinal fluid (CSF) leak from the lateral recess of the sphenoid sinus is rare when compared to leaks from other sites. The extended endonasal approach along with a transpterygoid extension provides adequate exposure for repair of these defects.

Materials and Methods

We retrospectively analyzed a series of seven patients who underwent eight transpterygoid approaches for repair of the CSF leak from the lateral recess of the sphenoid sinus. We analyzed the patient characteristics, site of leaks, type of repair done, and presence of increased intracranial pressure (ICP) in these individuals.

Results

Seven patients underwent eight transpterygoid approaches for CSF leaks from the lateral recess of the sphenoid sinus. The leak was bilateral in one patient. The materials used for repair consisted of fat, fascia lata, free mucosal flap or a vascularised nasoseptal flap, and fibrin glue. Evidence of increased ICP was found in five of the seven patients. CSF diversion was needed in three of the seven patients (two ventriculoperitoneal shunt and one thecoperitoneal shunt).

Conclusion

Endoscopic endonasal transpterygoid approach provides an excellent visualization of the skull-base defect and facilitates adequate instrument manipulation within the corridor, allowing successful repair of the defect with low rates of recurrence. Increased ICP can have a role in causing spontaneous CSF rhinorrhea from this location.

The pterygoclival ligament: a novel landmark for localization of the internal carotid artery during the endoscopic endonasal approach

Objective

The transpterygoid extension of the endoscopic endonasal approach provides exposure of the petrous apex, Meckel's cave, paraclival area, and the infratemporal fossa. Safe and efficient localization of the lacerum segment of the internal carotid artery (ICA) is a crucial part of such exposure. The aim of this study is to introduce a novel landmark for localization of the lacerum ICA.

Methods

Ten cadaveric heads were prepared for transnasal endoscopic dissection. The floor of the sphenoid sinus was drilled to expose an extension of the pharyngobasilar fascia between the sphenoid floor and the pterygoid process (the pterygoclival ligament). Several features of the pterygoclival ligament were assessed. In addition, 31 dry skulls were studied to assess features of the bony groove harboring the pterygoclival ligament.

Results

The pterygoclival ligament was identified bilaterally during drilling of the sphenoid floor in all specimens. The ligament started a few millimeters posterior to the posterior end of the vomer alae and invariably extended posterolaterally and superiorly to blend into the fibrous tissue around the lacerum ICA. The mean length of the ligament was 10.5 ± 1.7 mm. The mean distance between the anterior end of the ligament and midline was 5.2 ± 1.2 mm. The mean distance between the posterior end of the ligament and midline was 12.3 ± 1.4 mm. The bony pterygoclival groove was identified at the confluence of the vomer, pterygoid process of the sphenoid, and basilar part of the occipital bone, running from posterolateral to anteromedial. The mean length of the groove was 7.7 ± 1.8 mm. Its posterolateral end faced the anteromedial aspect of the foramen lacerum medial to the posterior end of the vidian canal. A clinical case illustration is also provided.

Conclusions

The pterygoclival ligament is a consistent landmark for localization of the lacerum ICA. It may be used as an adjunct or alternative to the vidian nerve to localize the ICA during endoscopic endonasal surgery.

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

Background  Surgical resection of parapharyngeal space (PPS) tumors is very challenging. An endoscopic-assisted surgical approach to this region requires detailed and precise anatomic knowledge. The main purpose of this study is to describe and compare the detailed anatomy of the PPS via transnasal transpterygoid (TP) and endoscopic-assisted transoral (TO) approaches. Materials and Methods  Six fresh injected cadaver heads (12 sides) were prepared for dissection of the PPS via TP and TO approaches. Computed tomography (CT) with image-based navigation (Navigation System II; Stryker, Kalamazoo, Michigan, United States) was used to identify bony structures around the PPS. Results  TP and TO approaches could both expose the detailed anatomical structures in the PPS. The TP approach can provide a direct route to the upper PPS, but it is limited inferiorly by the hard palate and laterally by the medial and lateral pterygoid muscles. However, the TO approach can provide a direct route to the lower PPS, but it is difficult to expose the area around the Eustachian tube. The styloglossus and stylopharyngeus muscles could be considered as the safe anterior boundary of the parapharyngeal internal carotid artery (ICA) with the TO approach. Dissection between the stylopharyngeus muscle and the superior pharyngeal constrictor muscle provides direct access to the parapharyngeal ICA. Conclusion  The TP and TO approaches provide new strategies to manage lesions in the PPS. The important neurovascular structures of the PPS could be identified with these approaches. The endoscopic-assisted TO approach can provide direct access to the parapharyngeal ICA.

Expanding the endoscopic transpterygoid corridor to the petroclival region: anatomical study and volumetric comparative analysis

OBJECTIVE The endoscopic endonasal transmaxillary transpterygoid (TMTP) approach has been the gateway for lateral skull base exposure. Removal of the cartilaginous eustachian tube (ET) and lateral mobilization of the internal carotid artery (ICA) are technically demanding adjunctive steps that are used to access the petroclival region. The gained expansion of the deep working corridor provided by these maneuvers has yet to be quantified. METHODS The TMTP approach with cartilaginous ET removal and ICA mobilization was performed in 5 adult cadaveric heads (10 sides). Accessible portions of the petrous apex were drilled during the following 3 stages: 1) before ET removal, 2) after ET removal but before ICA mobilization, and 3) after ET removal and ICA repositioning. Resection volumes were calculated using 3D reconstructions generated from thin-slice CT scans obtained before and after each step of the dissection. RESULTS The average petrous temporal bone resection volumes at each stage were 0.21 cm³, 0.71 cm³, and 1.32 cm³ (p < 0.05, paired t-test). Without ET removal, inferior and superior access to the petrous apex was limited. Furthermore, without ICA mobilization, drilling was confined to the inferior two-thirds of the petrous apex. After mobilization, the resection was extended superiorly through the upper extent of the petrous apex. CONCLUSIONS The transpterygoid corridor to the petroclival region is maximally expanded by the resection of the cartilaginous ET and mobilization of the paraclival ICA. These added maneuvers expanded the deep window almost 6 times and provided more lateral access to the petroclival region with a maximum volume of 1.5 cm³. This may result in the ability to resect small-to-moderate sized intradural petroclival lesions up to that volume. Larger lesions may better be approached through an open transcranial approach.

The Pedicled Buccal Fat Pad: Anatomical Study of the New Flap for Skull Base Defect Reconstruction After Endoscopic Endonasal Transpterygoid Surgery

Objectives To evaluate the efficacy and safety of using a buccal fat pad for endoscopic skull base defect reconstruction. Design Descriptive anatomical study with an illustrative case presentation. Setting Anatomical study was performed on 12 fresh human cadaver specimens with injected arteries (24 sides). Internal carotid artery was exposed in the coronal plane via the endoscopic transpterygoid approach. The pedicled buccal fat pad was used for reconstruction. Participants: 12 human cadaver head specimens; one patient operated using the proposed technique. Main outcome measures: Proximity of the buccal fat pad flap to the defect, compliance of the flap, comfort and safety of harvesting procedure, and compatibility with the Hadad-Bassagasteguy nasoseptal flap. Results: Harvesting procedure was performed using anterior transmaxillary corridor. The pedicled buccal fat pad flap can be used to pack the sphenoid sinus or cover the internal carotid artery from cavernous to upper parapharyngeal segment. Conclusion The buccal fat pad can be safely harvested through the same approach without external incisions and is compliant enough to conform to the skull base defect. The proposed pedicled flap can replace free abdominal fat in central skull base reconstruction. The volume of the buccal fat pad allows obliteration of the sphenoid sinus or upper parapharyngeal space.

Endoscopic versus Open Approach to the Infratemporal Fossa: A Cadaver Study

Introduction Various lateral and anterior approaches to access the infratemporal fossa (ITF) have been described. We provide our observations regarding the endoscopic transpterygoid and preauricular subtemporal approaches, listing their respective advantages and limitations through cadaveric dissection. Methods A cadaver study was performed on five adult specimens. An endoscopic transpterygoid approach to the ITF was completed bilaterally in three specimens, and an open preauricular ITF approach was performed bilaterally in two specimens. Results After completing the cadaveric dissections, we studied differences between the endoscopic transpterygoid approach and open preauricular subtemporal approaches in regard to exposure and ease of dissection of different structures in the ITF. Conclusions In comparison with a lateral approach, the endonasal endoscopic transpterygoid approach provides better visualization and more direct exposure of median structures such as the nasopharynx, eustachian tube, sella, and clivus. We concluded that the endoscopic transpterygoid approach can be utilized to resect benign lesions and some select group of malignancies involving the infratemporal and middle cranial fossae. Open approaches continue to play an important role, especially in the resection of extensive malignant tumors extending to these regions.

Use of the pedicled nasoseptal flap in the endoscopic management of cholesterol granulomas of the petrous apex

BACKGROUND

Nowadays the endoscopic approach represents a useful alternative to traditional surgical approaches in the treatment of cholesterol granulomas (CGs) of the petrous apex (PA). Recently the nasoseptal flap (NSF) has been employed to permit long-term patency of drainage site. The purpose of this study is to report our experience with the NSF in the endoscopic management of CG and to analyze the advantages, limitations, and outcomes of the technique.

METHODS

A retrospective analysis was carried out on 10 patients affected by CG of the PA who had been treated endoscopically, using the NSF.

RESULTS

An endoscopic transpterygoid approach was used for 6 patients and the remaining 4 were treated using the transclival approach. A NSF was used in all 10 cases. In 6 cases the flap was ipsilateral to the lesion whereas in 4 it was contralateral. In 90% of our patients no evidence of disease was observed after a mean follow-up period of 35.7 months, with resolution of their symptoms. One patient presented a recurrence because of a technical error (inadequate placement of the flap in the cavity), and has been retreated endoscopically.

CONCLUSION

The pedicled NSF seems to be helpful in avoiding the concentric growth of the granulomatous cyst epithelium while assuring ventilation and drainage of the cyst. However, bigger studies with longer-term follow-up are needed to confirm these findings. Correct and meticulous placement of the flap inside the cystic cavity is the most critical issue for the success of the procedure.

Endoscopic endonasal resection of skull base chondrosarcomas: technique and early results

OBJECT

The authors of this study sought to report the technique and early clinical outcomes of a purely endonasal endoscopic approach for resection of petroclival chondrosarcomas.

METHODS

Between 2010 and 2014, 8 patients (4 men and 4 women) underwent endonasal endoscopic operations to resect petroclival chondrosarcomas at 2 institutions. The patients' mean age was 44.8 years (range 30-64 years). One of the patients had previously undergone radiation therapy and another a staged craniotomy. Using volumetric software, an independent neuroradiologist assessed the extent of the resections on MRI scans taken immediately after surgery and at the 3-month follow-up. Immediate complications and control of symptoms were also recorded. In addition, the authors reviewed the current literature on surgical treatment of chondrosarcoma.

RESULTS

The mean preoperative tumor diameter and volume were 3.4 cm and 9.8 cm(3), respectively. Six patients presented with cranial neuropathies. Endonasal endoscopic surgery achieved > 95% resection in 5 of the 8 patients and < 95% resection in the remaining 3 patients. One of the 6 neuropathies resolved, and the remaining 5 partially improved. One instance of postoperative CSF leakage required a reoperation for repair; no other complications associated with these operations were observed. All of the patients underwent adjuvant radiotherapy.

CONCLUSIONS

According to the authors' experience, the endoscopic endonasal route is a safe and effective approach for the resection of appropriately selected petroclival chondrosarcomas.

Clinical correlates of the anatomical relationships of the foramen ovale: a radioanatomical study

Introduction Endonasal endoscopic transpterygoid approaches are commonly used techniques to access the infratemporal fossa and parapharyngeal space. Important endoscopic endonasal landmarks for the poststyloid parapharyngeal space, hence the internal carotid artery, include the mandibular nerve at the level of foramen ovale and the lateral pterygoid plate. This study aims to define the anatomical relationships of the foramen ovale, establishing its distance to other important anatomical landmarks such as the pterygoid process and columella. Methods Distances between the foramen ovale, foramen rotundum, and fixed anatomical landmarks like the columella and pterygoid process were measured using computed tomography (CT) scans and cadaveric dissections of the pterygopalatine and infratemporal fossae. Results The mean distances from the foramen ovale to columella and from the foramen rotundum to columella were found to be 9.15 cm and 7.09 cm, respectively. Analysis of radiologic measurements detected no statistically significant differences between sides or gender. Conclusions The pterygoid plates and V3 are prominent landmarks of the endonasal endoscopic approach to the infratemporal fossa and poststyloid parapharyngeal space. A better understanding of the endoscopic anatomy of the infratemporal fossa and awareness of the approximate distances and geometry among anatomical landmarks facilitates a safe and complete resection of lesions arising or extending to these regions.

Transpterygoid stent placement for management of a recurrent infratemporal fossa epidermoid cyst: a technical note

Epidermoid cysts (ECs) are benign congenital cysts that typically develop from misplaced stratified squamous epithelium during neural tube closure. They are most commonly encountered in the cerebellopontine angle, the fourth ventricle, and the region of the sella turcica. Recurrence of an EC or regrowth of residual components following surgery is known to occur, but the exact incidence is not defined. Repeat surgical removal is generally considered but may be complicated by significant morbidity. We present a novel endoscopic method by which to manage a recurrent EC of the infratemporal fossa using a silastic stent through a transpterygoid approach that permits periodic drainage of recurrent cyst material in the outpatient setting with minimal morbidity.