Endoscopic endonasal approach for the treatment of schwannomas of the pterygopalatine fossa: case report and review of the literature

Pterygopalatine fossa schwannoma-case report and literature review

INTRODUCTION

Schwannomas are well-differentiated, benign tumours that originate from the Schwann cells of nerve sheaths. They constitute 25-45% of all the head and neck tumours and can cause significant morbidity depending on the site of origin. The pterygopalatine fossa is the rarest site of involvement, with only a few cases reported in the literature.

CASE PRESENTATION

This is the case of a 46-year-old male who presented with a twelve [12] month history of left-sided facial pain and progressive swelling. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) revealed a large soft tissue lesion located in the left pterygopalatine fossa (PPF). Surgical management is presented, and technical details of the repair are discussed. At one year follow-up, there were no signs of recurrence, and the cosmetic outcome was satisfactory.

DISCUSSION

This case is one of a handful of reported cases of PPF schwannomas in the English literature. Although a significant percentage of schwannomas arise in the head and neck region, the pterygopalatine fossa is the rarest site of involvement. Due to its clinically inaccessible location and complex connections, the pterygopalatine fossa can act as a natural conduit for the spread of inflammatory and neoplastic diseases in the head and neck.

CONCLUSION

Currently, the endoscopic endonasal approach (EEA) is preferred due to its safety and good oncologic outcome. There is also decreased morbidity as it is minimally invasive. Furthermore, surgeons embarking on the EEA should be equipped with an image guidance system and be trained in advanced endoscopic techniques. However, the open approach remains a reliable and proven surgical method to treat large tumours located within this intricate and inaccessible area.

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

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

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.

Trigeminal Schwannomas in Middle Fossa Could Breach into Subdural Space: Report of 4 Cases and Review of Literature

OBJECTIVE

The objectives of this study were to report 4 cases diagnosed with trigeminal schwannomas (TS), among whom tumor in epidural space of middle fossa broke through dura mater into subdural space, and to analyze the potential reason for recurrence of TS in middle fossa after surgical removal by endoscopic endonasal approach (EEA) or interdural approach.

METHODS

The information of 4 patients diagnosed with TS who were surgically treated was retrospectively analyzed and the selection of approaches, surgical strategies, and potential reason for recurrence after middle fossa TS removal by EEA and interdural approach were discussed.

RESULTS

During last 10 years, 43 patients with TS received surgical treatment at Xuan Wu Hospital of Capital Medical University, among whom 1 patient with TS extending from middle fossa to infratemporal fossa was first treated by EEA, then the tumor recurred and the patient underwent a second operation via a frontotemporal subdural approach. During the second operation, we found part of tumor had broken through the dura mater into subdural space. Moreover, this phenomenon was detected in another 3 patients with middle-posterior fossa TS.

CONCLUSIONS

TS in middle fossa has been widely believed to be totally located at epidural space, whereas we found that it could occasionally breach into subdural space and accept blood supply from the pial artery. We believe this could be the potential reason for recurrence after tumor resection by EEA and interdural approach.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Assessment of the Endoscopic Endonasal Transclival Approach for Surgical Clipping of Anterior Pontine Anterior-Inferior Cerebellar Artery Aneurysms

OBJECTIVE

Aneurysms of the anterior pontine segment of the anterior-inferior cerebellar artery (AICA) are uncommon. Their treatment is challenging because critical neurovascular structures are adjacent to it and the available surgical corridors are narrow and deep. Although endoscopic endonasal approaches are accepted for treating midline skull base lesions, their role in the treatment vascular lesions remains undefined. The present study is aimed to assess the anatomic feasibility of the endoscopic endonasal transclival (EET) approach for treating anterior pontine AICA aneurysms and compare it with the subtemporal anterior transpetrosal (SAT) approach.

METHODS

Twelve cadaveric specimens were prepared for surgical simulation. The AICAs were exposed using both EET and SAT approaches. Surgical window area and the length of the exposed artery were measured. The distance from the origin of the artery to the clip applied for proximal control was measured. The number of AICA perforators exposed and the anatomic features of each AICA were recorded.

RESULTS

The EET approach provided a wider surgical window area compared with the SAT (P < 0.001). More AICA perforators were visualized using the EET approach (P < 0.05). To obtain proximal control of the AICA, an aneurysm clip could be applied closer to the origin of AICA using EET (0.2 ± 0.42 mm) compared with SAT (6.26 ± 3.4 mm) (P < 0.001).

CONCLUSION

Clipping anterior pontine AICA aneurysms using the EET approach is feasible. Compared with SAT, the EET approach provides advantages in surgical window area, ensuring proximal control before aneurysm dissection, visualization of perforating branches, and better proximal control.

The expanding role of the endonasal endoscopic approach in pituitary and skull base surgery: A 2014 perspective

BACKGROUND

The past two decades have been the setting for remarkable advancement in endonasal endoscopic neurosurgery. Refinements in camera definition, surgical instrumentation, navigation, and surgical technique, including the dual surgeon team, have facilitated purely endonasal endoscopic approaches to the majority of the midline skull base that were previously difficult to access through the transsphenoidal microscopic approach.

METHODS

This review article looks at many of the articles from 2011 to 2014 citing endonasal endoscopic surgery with regard to approaches and reconstructive techniques, pathologies treated and outcomes, and new technologies under consideration.

RESULTS

Refinements in approach and closure techniques have reduced the risk of cerebrospinal fluid leak and infection. This has allowed surgeons to more aggressively treat a variety of pathologies. Four main pathologies with outcomes after treatment were identified for discussion: pituitary adenomas, craniopharyngiomas, anterior skull base meningiomas, and chordomas. Within all four of these tumor types, articles have demonstrated the efficacy, and in certain cases, the advantages over more traditional microscope-based techniques, of the endonasal endoscopic technique.

CONCLUSIONS

The endonasal endoscopic approach is a necessary tool in the modern skull base surgeon's armamentarium. Its efficacy for treatment of a wide variety of skull base pathologies has been repeatedly demonstrated. In the experienced surgeon's hands, this technique may offer the advantage of greater tumor removal with reduced overall complications over traditional craniotomies for select tumor pathologies centered near the midline skull base.