Endoscopic Endonasal Approaches to the Medial Intraconal Space: Comparison of Transethmoidal and Prelacrimal Corridors

Abstract

Background Endoscopic transethmoidal and prelacrimal approaches can access the medial intraconal space (MIS). Objective This study aimed to compare advantages and drawbacks of these two approaches, and to explore their appropriate indications for management of lesions at various locations within the MIS. Methods Six injected cadaveric specimens were dissected using an endonasal approach performing a transethmoidal approach on one side and a prelacrimal approach on the contralateral side. The MIS was divided into three Zones: Zone 1 was defined as the area above the superior border of the medial rectus muscle (MRM), Zone 2 as the area between the MRM and the optic nerve, and Zone 3 as the area below the inferior border of MRM. The exposure provided by these two approaches to various Zones within the MIS was assessed and compared. Results The average height of Zone 1 to 3 was 10.35 ± 0.45 mm, 11.07 ± 0.59 mm, and 6.53 ± 0.59 mm, respectively. Both approaches provided adequate exposure of Zone 2 and 3; however, the prelacrimal approach provided direct exposure of the posterosuperior aspect of Zone 2 without retraction of MRM. Retraction of MRM was unavoidable using a transethmoidal approach to enhance further exposure. Access to Zone 1 was adequately achieved through the corridor between superior oblique muscle and MRM via a transethmoidal corridor. Conclusion Conceptualizing the MIS into the three aforementioned Zones seems beneficial to select the optimal approach for lesions restricted to each specific Zone. Both the transethmoidal and prelacrimal approaches provide adequate exposure for select lesions in the MIS.

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

“…28,29 Thus, as the clinical case presented in this study, the OPSL may serve as a reliable marker to prevent inadvertent damage to the orbital contents when addressing lesions in the PPF not beyond the lateral border of the OPSL. 30 Likewise, for surgeries in the medial orbit, staying above the lateral border of OPSL could potentially avoid damage to structures within the PPF.…”

Editorial

“…Other studies that are impactful in the realm of endoscopic surgery, includes a cadaver study by Li et al 14 on surgical techniques to access the medial intraconal space (MIS) and a meta-analysis by Vinciguerra, et al 15 on two treatments options for Epiphora: external vs endoscopic approaches. In the first study, Li et al 14 compared the advantage and disadvantage of transethmoidal and prelacrimal approaches to access the medial intraconal space (MIS), and reported that while both approaches are capable to assess MIS, each approach has its own advantages for assessing different zones within the MIS. The 2nd study 15 attempted to examine different post-surgical medical therapies that may improve surgical outcomes of external dacryocystorhinostomy (EXT-DCR) and endoscopic endonasal dacryocystorhinostomy (END-DCR).…”

“…Other studies that are impactful in the realm of endoscopic surgery, includes a cadaver study by Li et al. 14 on surgical techniques to access the medial intraconal space (MIS) and a meta-analysis by Vinciguerra, et al. 15 on two treatments options for Epiphora: external vs endoscopic approaches.…”

“…In the first study, Li et al. 14 compared the advantage and disadvantage of transethmoidal and prelacrimal approaches to access the medial intraconal space (MIS), and reported that while both approaches are capable to assess MIS, each approach has its own advantages for assessing different zones within the MIS. The 2nd study 15 attempted to examine different post-surgical medical therapies that may improve surgical outcomes of external dacryocystorhinostomy (EXT-DCR) and endoscopic endonasal dacryocystorhinostomy (END-DCR).…”

Endoscopic Endonasal Approach to the Pterygopalatine Fossa and Infratemporal Fossa: Comparison of the Prelacrimal and Denker’s Corridors

“…14 Its use has been widely expanded to remove tumors arising in the pterygopalatine fossa and infratemporal fossa, 15,16 as well as the management of lesions involving the orbital floor, inferior or medial intraconal space, lateral recess of sphenoid sinus, and middle cranial fossa. [17][18][19][20][21] Despite its limited instrument maneuverability, the advantages of a prelacrimal approach include sparing part of the lateral nasal wall, the nasolacrimal duct and posterior nasal septum. 14,15 Preservation of the aforementioned structures may be beneficial for maintenance of post-operative nasal function, which is particularly important when managing benign lesions.…”