[Endoscopic approaches to the orbit]

Three-Dimensional Radiologic Study on Index Measurement of Endonasal Endoscopic Optic Nerve Decompression

OBJECTIVE

To provide the radiologic basis for the clinical application of endonasal endoscopic optic nerve decompression (EEOND).

METHODS

CTA images were used to observe the optic canal (OC) and related structures of 60 patients (120 sides) with normal nasal, paranasal sinuses, OC, and other related structures.

RESULTS

Optic canal could be classified as: the canal (10 sides, 8.33%), the semicanal (25 sides, 20.83%), the impression (49 sides, 40.83%), and the nonimpression (36 sides, 30%). According to its relationships with the sinuses, OC could be further typed as: ethmoid sinus (22 sides, 18.3%), sphenoid sinus (38 sides, 31.7%), ethmoid and sphenoid sinus (60 sides, 50%). The thickness of OC medial wall is about 1.11 ± 0.24 mm at orbital mouth, 0.87 ± 0.25 mm at middle part and 1.19 ± 0.27 mm at cranial mouth. The arc length of OC bone wall which can be opened from the sinus cavity is about 7.18 ± 0.76 mm at orbital mouth, 8.27 ± 0.93 mm at middle part, and 6.98 ± 0.89 mm at cranial mouth. The length of the OC medial wall is 12.18 ± 1.35 mm. In the three-dimensional Cartesian coordinate system that origined with the last point of middle turbinate root and oriented by temporal side, front side, and superior side, the coordinates of midpoints of OC medial wall are: (3.64 ± 1.11, 8.48 ± 1.65, 23.14 ± 2.67) at orbital mouth, (0.16 ± 1.21, 3.99 ± 1.80, 24.85 ± 2.67) at middle part, and (-3.59 ± 1.22, 0.77 ± 2.13, 26.39 ± 2.68) at cranial mouth. One length unit on the axes is a millimeter.

CONCLUSION

Computed tomography (CT) scanning technique can measure the data of the OC in EEOND. It has great guiding significance for clinical operation.

[Surgical approaches of tumors of the posterior cone of the orbit]

The surgical management of posterior orbital tumors is complex because it is an anatomical area located at the borders between the face and the skull base. The goal of the procedures carried-out in this area is to resect the tumor while preserving vision by using the safest possible approach. The aim of our work was to determine, in the light of our experience and of a review of the literature, the advantages and drawbacks of the numerous approaches described.

Endoscopic endonasal optic nerve and orbital apex decompression for nontraumatic optic neuropathy: surgical nuances and review of the literature

OBJECT

While several approaches have been described for optic nerve decompression, the endoscopic endonasal route is gaining favor because it provides excellent exposure of the optic canal and the orbital apex in a minimally invasive manner. Very few studies have detailed the experience with nontraumatic optic nerve decompressions, whereas traumatic cases have been widely documented. Herein, the authors describe their preliminary experience with endoscopic endonasal decompression for nontraumatic optic neuropathies (NONs) to determine the procedure's efficacy and delineate its potential indications and limits.

METHODS

The medical reports of patients who had undergone endoscopic endonasal optic nerve and orbital apex decompression for NONs at the Lyon University Neurosurgical Hospital in the period from January 2012 to March 2014 were reviewed. For all cases, clinical and imaging data on the underlying pathology and the patient, including demographics, preoperative and 6-month postoperative ophthalmological assessment results, symptom duration, operative details with video debriefing, as well as the immediate and delayed postoperative course, were collected from the medical records.

RESULTS

Eleven patients underwent endoscopic endonasal decompression for NON in the multidisciplinary skull base surgery unit of the Lyon University Neurosurgical Hospital during the 27-month study period. The mean patient age was 53.4 years, and there was a clear female predominance (8 females and 3 males). Among the underlying pathologies were 4 sphenoorbital meningiomas (36%), 3 optic nerve meningiomas (27%), and 1 each of trigeminal neuroma (9%), orbital apex meningioma (9%), ossifying fibroma (9%), and inflammatory pseudotumor of the orbit (9%). Fifty-four percent of the patients had improved visual acuity at the 6-month follow-up. Only 1 patient whose sphenoorbital meningioma had been treated at the optic nerve atrophy stage continued to worsen despite surgical decompression. The 2 patients presenting with preoperative papilledema totally recovered. One case of postoperative epistaxis was successfully treated using balloon inflation, and 1 case of air swelling of the orbit spontaneously resolved.

CONCLUSIONS

Endoscopic endonasal optic nerve decompression is a safe, effective, and minimally invasive technique affording the restoration of visual function in patients with nontraumatic compressive processes of the orbital apex and optic nerve. The timing of decompression remains crucial, and patients should undergo such a procedure early in the disease course before optic atrophy.

How I do it: the endoscopic endonasal optic nerve and orbital apex decompression

BACKGROUND

With the refinement of the technique, endoscopic endonasal surgery increases its field of indications. The orbital compartment is among the locations easily reached through the nostril. This anteromedial approach has been described primarily for inflammatory or traumatic diseases, with few data for tumoral diseases.

METHOD

Since 2010, this route has been used at our institution either for decompression or for biopsy of orbital tumoral diseases.

FINDINGS/CONCLUSIONS

Even if further studies are warranted, this strategy proved to be beneficial for patients, with improvements in visual outcome. In this article, the authors summarize their technique and their experience with endonasal endoscopic orbital decompression.

KEY POINTS

Nasal and sphenoidal anatomies determine the feasibility and risks for doing an efficient medial optic or orbit decompression. • Techniques and tools used are those developed for pituitary surgery. • A middle turbinectomy and posterior ethmoidectomy are mandatory to expose the medial wall of the orbit. • The Onodi cell is a key marker for the optic canal and must be opened up with caution. • The lamina papyracea is opened first with a spatula and the optic canal opened up by a gentle drilling under continuous irrigation from distal to proximal. • Drilling might always be used under continuous irrigation to avoid overheating of the optic nerve. An ultrasonic device can be used as well. • The nasal corridor is narrow and instruments may hide the infrared neuronavigation probe. To overcome this issue, a magnetic device could be useful. • Doppler control could be useful to locate the ICA. • The optic canal must be opened up from the tuberculum of the sella to the orbital apex and from the planum (anterior cranial fossa) to the lateral OCR or ICA canal • At the end of the procedure, the optic nerve becomes frequently pulsatile, which is a good marker of decompression.

Anatomic analysis specific for the endoscopic approach to the inferior, medial and lateral orbit

INTRODUCTION

The endoscopic approaches to the medial and inferior orbital walls have continued to grow in popularity. The ability to provide a safe approach to the orbit through this technique has been described in a handful of studies. Even though metric analyses have been conducted on orbital anatomy, few have outlined the anatomical relations pertinent to endoscopic surgery. The goal is to provide improved understanding of the complex anatomy encountered through anatomical dissections and metric analysis of the orbit. This information could assist in approach selection during preoperative planning.

METHODS

Anatomical dissections via transantral and endonasal approaches were used to define the limits with current endoscopic sinus surgery instrumentation. The surface area was then calculated of the floor and medial wall to assess access created by the approaches. The path of the infraorbital canal was conducted to assess its placement within the orbital floor.

RESULTS

The transantral and endonasal approaches to the orbit provided an adequate surgical window inferiorly and medially. This was confirmed by the surface area calculations. Access laterally was also possible, however, it became limited as dissection advanced superior to the lateral rectus muscle. The infraorbital canal was located consistently at midline on the orbital floor.

CONCLUSION

Endoscopic access to the medial and inferior parts of the orbit is feasible and creates adequate access with current instrumentation. Knowing the surgical boundaries and the amount of exposure created can assist the surgeon in deciding a minimally invasive approach.

[Shifting paradigm in skull base surgery: Roots, current state of the art and future trends of endonasal endoscopic approaches]

During the last two decades, endoscopic endonasal approach has completed the minimally invasive skull base surgery armamentarium. Endoscopic endonasal skull base surgery (EESBS) was initially developed in the field of pituitary adenomas, and gained an increasing place for the treatment of a wide variety of skull base pathologies, extending on the midline from crista galli process to the occipitocervical junction and laterally to the parasellar areas and petroclival apex. Until now, most studies are retrospective and lack sufficient methodological quality to confirm whether the endoscopic endonasal pituitary surgery has better results than the microsurgical trans-sphenoidal classical approach. The impressions of the expert teams show a trend toward better results for some pituitary adenomas with the endoscopic endonasal route, in terms of gross total resection rate and probably more comfortable postoperative course for the patient. Excepting intra- and suprasellar pituitary adenomas, EESBS seems useful for selected lesions extending onto the cavernous sinus and Meckel's cave but also for clival pathologies. Nevertheless, this infatuation toward endoscopic endonasal approaches has to be balanced with the critical issue of cerebrospinal fluid leaks, which constitutes actually the main limit of this approach. Through their experience and a review of the literature, the authors aim to present the state of the art of this approach as well as its limits.