Infraorbital nerve transposition to expand the endoscopic transnasal maxillectomy

Infraorbital canal variants and its clinical and surgical implications. A systematic review

BACKGROUND

Recent literature highlights anomalous cranial nerves in the sinonasal region, notably in the sphenoid and maxillary sinuses, linked to anatomical factors. However, data on the suspended infraorbital canal (IOC) variant is scarce in cross-sectional imaging. Anatomical variations in the sphenoid sinuses, including optic, maxillary, and vidian nerves, raise interest among specialists involved in advanced sinonasal procedures. The infraorbital nerve's (ION) course along the orbital floor and its abnormal positioning within the orbital and maxillary sinus region pose risks of iatrogenic complications. A comprehensive radiological assessment is crucial before sinonasal surgeries. Cone-beam computed tomography (CBCT) is preferred for its spatial resolution and reduced radiation exposure.

OBJECTIVE

The aim of this study was to describe the prevalence of anatomical variants of the infraorbital canal (IOC) and report its association with clinical condition or surgical implication.

METHODS

We searched Medline, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS databases from their inception up to June 2023. Two authors independently performed the search, study selection, data extraction, and assessed the methodological quality with assurance tool for anatomical studies (AQUA). Finally, the pooled prevalence was estimated using a random effects model.

RESULTS

Preliminary results show that three types are prevalent, type 1: the IOC does not bulge into the maxillary sinus (MS); therefore, the infraorbital foramen through the anterior wall of MS could be used for identification of the ION. Type 2: the IOC divided the orbital floor into medial and lateral aspects. Type 3: the IOC hangs in the MS and the entire orbital floor lying above the IOC. From which the clinical implications where mainly surgical, in type 1 the infraorbital foramen through the anterior wall of MS could be used for identification of the ION, while in type 2, since the lateral orbital floor could not be directly accessed an inferiorly transposition of ION is helpful to expose the lateral orbital wall directly with a 0 scope; or using angled endoscopes and instruments, however, the authors opinion is that direct exposure potentially facilitates the visualization and management in complex situations such as residual or recurrent mass, foreign body, and fracture located at the lateral aspect of the canal. Lastly, in type 3, the ION it's easily exposed with a 0° scope.

CONCLUSIONS

This systematic review identified four IOC variants: Type 1, within or below the MS roof; Type 2, partially protruding into the sinus; Type 3, fully protruding into the sinus or suspended from the roof; and Type 4, in the orbital floor. Clinical recommendations aim to prevent nerve injuries and enhance preoperative assessments. However, the lack of consistent statistical methods limits robust associations between IOC variants and clinical outcomes. Data heterogeneity and the absence of standardized reporting impede meta-analysis. Future research should prioritize detailed reporting, objective measurements, and statistical approaches for a comprehensive understanding of IOC variants and their clinical implications. Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/UGYFZ .

Surgery of Inverted Papilloma of the Maxillary Sinus via Translacrimal Approach-Long-Term Outcome and Literature Review

There are several differential diagnoses of unilateral sinus disease. One of these is inverted papilloma (IP) of the maxillary sinus, which is a common benign tumor with a substantial rate of malignant transformation. In general, endoscopic endonasal techniques for addressing the tumor are favored nowadays instead of classical external approaches. The aim of this retrospective study was to investigate the long-term outcome of inverted papilloma treated endoscopically via the prelacrimal approach. We reviewed 17 patients with primary or recurrent IP of the maxillary sinus that were treated via the prelacrimal endoscopic endonasal technique. After a median follow-up period of 45.9 months (3.8 years), none of the 17 included patients showed signs of recurrent disease and no serious complications were reported. Hypoesthesia of the incisors was reported by four patients and was resolved with time in one. All of the maxillary sinuses could be fully visualized with the flexible endoscope. IP is an important differential diagnosis in the clinical finding of unilateral nasal polypoid lesions. The prelacrimal approach is an effective and safe method in the treatment of IP with limited patient morbidity.

Anatomical Variants of the Infraorbital Canal: Implications for the Prelacrimal Approach to the Orbital Floor

Background

The infraorbital nerve (ION) and its canal are important landmarks during surgical approaches to the orbital floor and pterygopalatine fossa. However, variations in the anatomy of the infraorbital canal and its corresponding neurovascular bundle may impact the access.

Objective

To investigate anatomic variants of the infraorbital canal from a prelacrimal endoscopic perspective and to explore the impact of these variants on exposing the lateral orbital floor.

Methods

Ten cadaveric specimens (20 sides) were dissected through an endonasal prelacrimal approach. Anatomic variants of the ION including location, branching pattern, and relationship to the infraorbital artery were assessed. The need for ION transposition to increase exposure of the lateral orbital floor was also investigated.

Results

Incidence of previously described Types 1, 2, and 3 ION variants were 30.0%, 60.0%, and 10.0%, respectively. Although the orbital floor could be directly accessed in Type 1 and Type 3 IONs, transposition of the ION was necessary to expose the lateral orbital floor in 5 of 12 sides (42%) for Type 2 ION. Bony dehiscence of the orbital floor was identified in 8 of 20 sides (40%) and branching of the ION in 2 of 20 sides (10%).

Conclusion

Anatomic variations of the infraorbital canal impact surgical exposure of the orbital floor via a prelacrimal approach. Type 1 and Type 3 ION variants allow a direct exposure of the entire orbital floor. A Type 2 ION may require transposition of the nerve to adequately expose the lateral orbital floor.

Transnasal prelacrimal approach to the inferior intraconal space: a feasibility study

BACKGROUND

Endonasal access to the inferomedial and inferolateral intraconal space via the orbital floor has not been reported. The primary purpose of this study was to assess the feasibility of accessing the inferior intraconal space through the orbital floor via a transnasal prelacrimal approach. Secondarily, it aims to highlight anatomical relationships of neurovascular structures in this space, as a requirement to prevent complications.

METHODS

Six cadaveric heads (12 sides) were dissected using a transnasal prelacrimal approach. The orbital floor, medial to the infraorbital canal, was removed and the periorbita opened to expose the inferior rectus muscle. The inferomedial and inferolateral intraconal space was accessed alongside the medial and lateral border of inferior rectus muscle, respectively. Various anatomical relationships of adjacent neurovascular structures were recorded, and the distances among the recti muscles and optic nerve were also measured.

RESULTS

The infraorbital nerve is located at the inferolateral aspect of inferior rectus muscle. In the inferomedial intraconal space, we identified the inferomedial muscular trunk of the ophthalmic artery, optic nerve, and branches of the oculomotor nerve; whereas the inferolateral intraconal space contained the inferolateral muscular trunk of ophthalmic artery, branches of the oculomotor and nasociliary nerve, and abducens nerve. Distances from the medial, inferior, and lateral recti muscles to the optic nerve were (mean ± standard deviation) 4.70 ± 1.18 mm, 5.60 ± 0.93 mm, and 7.98 ± 1.99 mm, respectively. Distances from the inferior rectus muscle to the inferior borders of medial and lateral recti muscles were 4.45 ± 1.23 mm and 8.77 ± 1.80 mm.

CONCLUSION

It is feasible to access the inferior intraconal space through the orbital floor via a transnasal prelacrimal approach. The access may be subdivided into inferomedial and inferolateral corridors according to the entry point at the medial or lateral border of the inferior rectus muscle. Neurovascular structures in the inferior intraconal space are visualized directly, which should enhance their preservation.