This study was done to compare the advantages and drawbacks of these two approaches and to explore their appropriate indications for the management of lesions at various locations within the MIS.

6 injected cadaveric specimens were dissected using an endonasal approach performing a transethmoidal approach on one side and a pre-lacrimal approach on the contralateral side. The MIS was divided into three zones. The exposure provided by these two approaches to various Zones within the MIS was assessed and compared.

Both approaches provided adequate exposure of Zone 2 and 3; however, the pre-lacrimal approach provided direct exposure of the posterosuperior aspect of Zone 2 without retraction of MRM. The 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.

The study concluded through its findings that 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 pre-lacrimal approaches provide adequate exposure to select lesions in the MIS.