Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model

Fully endoscopic transnasal approach to the jugular foramen: anatomic study and clinical considerations

BACKGROUND AND IMPORTANCE

To describe a transnasal endoscopic route to the jugular foramen and the endoscopic anatomy of the infratemporal fossa.

CLINICAL PRESENTATION

Endoscopic transnasal dissection of the infratemporal fossa was performed in 3 injected fresh heads (1 head only in arteries and 2 heads in arteries and veins). Two other double-injected specimens were dissected externally (2 of them side laterally and 1 anteriorly) to compare the different views and better understand the 3-dimensionality of the region.Detailed endoscopic anatomy of the infratemporal fossa was clearly observed. The realization of a septal and posterior maxillary window allows surgeons to gain space to the jugular foramen. The ability to manage the vessels, especially the veins, and identify the muscles is mandatory. The fundamental role of the vidian canal in targeting the anterior genu of the internal carotid artery is confirmed. The role of the maxillary and mandibular branches of the trigeminal nerve and the eustachian tube in this kind of approach is critical.

CONCLUSION

A fully transnasal endoscopic route to the jugular foramen is feasible. The most important landmark for this kind of approach is the eustachian tube.

The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave

Object

In this paper the authors' goal was to present their clinical experience with lesions of the pterygopalatine fossa, infratemporal fossa, lateral sphenoid sinus, cavernous sinus, petrous apex, and Meckel cave using simple and extended endoscopic transpterygoid approaches to the lateral skull base.

Methods

Simple and expanded endoscopic transpterygoid approaches were performed in a series of 13 patients with varying pathology that included lateral sphenoid sinus encephaloceles, benign and malignant sinonasal tumors, and lesions of neural origin.

Results

A gross-total resection was achieved in 5 of 9 patients, while a subtotal resection for tissue diagnosis and cytoreduction prior to further adjuvant treatment was performed in the remaining patients. Sphenoid sinus encephaloceles were successfully repaired via a transpterygoid approach in all 4 patients. The skull base defect was reconstructed using a multilayered closure. One patient developed a postoperative CSF leak, which was successfully treated conservatively. The mean follow-up time was 16 months. Five patients complained of recurrent sinusitis. One patient experienced xerophthalmia and palate numbness. Three patients had died by the time of this report. Two patients died of unrelated causes. The third patient died of progression of an aggressive pterygopalatine osteosarcoma despite undergoing cytoreductive surgery and adjuvant chemotherapy.

Conclusions

An endoscopic transpterygoid approach is a minimally invasive endoscopic approach for lesions located or extending to the pterygopalatine fossa, infratemporal fossa, petrous apex, Meckel cave, and other regions of the paramedian skull base.

Transnasal endoscopic skull base surgery: what are the limits?

PURPOSE OF REVIEW

Endoscopic skull base surgery has significantly revolutionized the management of skull base disease. Our review focuses on the recent literature relating to endoscopic skull base surgery emphasizing its limitations.

RECENT FINDINGS

Current literature continues to expand the indications for endoscopic approaches to the skull base. Experience in endoscopic techniques continues to grow across the world. This is due in part to advances in instrumentation and technology, improvements in technique and, more importantly, an increase in the number of surgeons with training in endoscopic techniques. Long-term outcome data remain sparse.

SUMMARY

The limitations in endoscopic skull base surgery have not been reached. Increasing experience and improvement in technology will likely expand current indications. Future studies should focus on outcome analysis.

Endoscopic Approach to the Infratemporal Fossa

OBJECTIVE

Classic surgical exposures of the infratemporal fossa region, including the adjacent intracranial space, temporal bone, and sinonasal region, require the extensive exposure associated with the transcranial, transfacial, and transmandibular approaches with their inherent neurological and cosmetic morbidities. In this study, we evaluated the feasibility and exposure afforded by combining 2 endoscopic transmaxillary approaches, endonasal and Caldwell-Luc supplement, to the infratemporal fossa.

METHODS

Endoscopic transmaxillary dissection was performed in 4 formalin-fixed cadaver heads (8 sides). We quantified the extent of exposure achieved within the pterygopalatine and infratemporal fossae after our initial dissection, which was endonasal with a medial antrostomy, and after addition of a Caldwell-Luc incision with an anterior antrostomy. Complementing this anatomic study, we report on a patient in whom this endoscopic transmaxillary approach combining the endonasal and Caldwell-Luc approaches was used for resection of a trigeminal schwannoma in the infratemporal fossa.

RESULTS

The combination of these 2 endoscopic transmaxillary approaches enabled visualization of the entire region of the pterygopalatine fossa and anteromedial aspect of the infratemporal fossa. Additional posterolateral exposure of the infratemporal fossa requires significant traumatic traction on the nose. Addition of the Caldwell-Luc transmaxillary approach exposed the remainder of the infratemporal fossa, including the mandibular nerve and branches, middle meningeal artery, and even the distal cervical portion of the internal carotid artery.

CONCLUSION

Endoscopic exposure of the infratemporal fossa is feasible. Using the combination of the endonasal and Caldwell-Luc approaches for direct transmaxillary access significantly extended exposure, allowing safe and effective resection of infratemporal fossa lesions.

Endoscopic study for the pterygopalatine fossa anatomy: via the middle nasal meatus-sphenopalatine foramen approach

OBJECTIVE

The purposes of this study were to locate the constant anatomic landmarks, which are very important and helpful for endoscopic surgery and not well described for the pterygopalatine fossa (PPF) surgery via the middle nasal meatus-sphenopalatine foramen approach to establish a safe surgical mode.

METHODS

Eight cases of adult skull specimens were selected for the simulated surgery. The Messerklinger surgical approach was used under the endoscope. The uncinate process was removed successively, and the anterior ethmoid sinus and posterior ethmoid sinus were opened. The opening of the maxillary sinus was identified and was expanded forward and backward. The ethmoidal crest was found and was used as an anatomic landmark to find the sphenopalatine foramen. The sphenopalatine artery was protected and was used as a guide to enter the PPF region. The sphenopalatine artery was followed conversely to anatomize the blood vessels and nerves in the PPF.

RESULTS

It was found that our surgical procedure provides a clear view of the constant anatomic landmark including ethmoidal crest and sphenopalatine foramen. By retrograde dissection, following the sphenopalatine artery, which runs out of the sphenopalatine foramen behind the ethmoidal crest, the internal maxillary artery (IMA) and the branches of the IMA in the PPF were exposed. Posterior to the sphenopalatine artery, the typical Y-shaped structure with the pterygopalatine ganglion as the center was visible when the IMA and its branches were moved downward and outward. The Y structure, which is consisted of the pterygopalatine ganglion, branches of the internal maxillary nerve, vidian nerve, and descending palatine nerve, served as the other anatomic landmark. By following the Y structure, it was easy to locate the pterygoid canal, foramen rotundum, and the infraorbital nerve, and the integrity of the nerve structure could be protected.

CONCLUSION

Endoscopic PPF surgery via the middle nasal meatus-sphenopalatine foramen approach is safe, and the ethmoidal crest, sphenopalatine foramen, and Y structure with the pterygopalatine ganglion in the center are important anatomic landmarks that can be referred to during the surgery.

The front door to meckel's cave: an anteromedial corridor via expanded endoscopic endonasal approach- technical considerations and clinical series

OBJECTIVE

Tumors within Meckel's cave are challenging and often require complex approaches. In this report, an expanded endoscopic endonasal approach is reported as a substitute for or complement to other surgical options for the treatment of various tumors within this region.

METHODS

A database of more than 900 patients who underwent the expanded endoscopic endonasal approach at the University of Pittsburgh Medical Center from 1998 to March of 2008 were reviewed. From these, only patients who had an endoscopic endonasal approach to Meckel's cave were considered. The technique uses the maxillary sinus and the pterygopalatine fossa as part of the working corridor. Infraorbital/V2 and the vidian neurovascular bundles are used as surgical landmarks. The quadrangular space is opened, which is bound by the internal carotid artery medially and inferiorly, V2 laterally, and the abducens nerve superiorly. This offers direct access to the anteroinferomedial segment of Meckel's cave, which can be extended through the petrous bone to reach the cerebellopontine angle.

RESULTS

Forty patients underwent an endoscopic endonasal approach to Meckel's cave. The most frequent abnormalities encountered were adenoid cystic carcinoma, meningioma, and schwannomas. Meckel's cave and surrounding structures were accessed adequately in all patients. Five patients developed a new facial numbness in at least 1 segment of the trigeminal nerve, but the deficit was permanent in only 2. Two patients had a transient VIth cranial nerve palsy. Nine patients (30%) showed improvement of preoperative deficits on Cranial Nerves III to VI.

CONCLUSION

In selected patients, the expanded endoscopic endonasal approach to the quadrangular space provides adequate exposure of Meckel's cave and its vicinity, with low morbidity.

Endoscopic skull base surgery

Endoscopic skull base surgery has undergone rapid advancement in the past decade moving from pituitary surgery to suprasellar lesions and now to a myriad of lesions extending from the cribriform plate to C2 and laterally out to the infratemporal fossa and petrous apex. Evolution of several technological advances as well as advances in understanding of endoscopic anatomy and the development of surgical techniques both in resection and reconstruction have fostered this capability. Management of benign disease via endoscopic methods is largely accepted now but more data is needed before the controversy on the role of endoscopic management of malignant disease is decided. Continued advances in surgical technique, navigation systems, endoscopic imaging technology, and robotics assure continued brisk evolution in this expanding field.