Comparing the Pterional, Supraorbital, Supraorbital with Orbital Osteotomy, and Extended Endoscopic Transplanum Approaches for Reaching the Anterior Communicating Artery Complex: An Anatomical Study

Background:: About 30 to 37% of intracranial aneurysms occur at the anterior communicating artery (ACoA) complex, making it one of the most common locations for cerebral aneurysms. Frequent anatomical variations, deep interhemispheric location, and the perforators that supply important structures are several factors that contribute to the complexity of ACoA aneurysms. Recently, several minimally invasive approaches have been implemented to treat these aneurysms while simultaneously reducing brain exposure and retraction, including microscopic and endoscopic approaches. However, no anatomical studies analyzing the efficacy of reaching the ACoA complex between microsurgical and endoscopic approaches have been conducted.

Methods:: Right-sided the pterional (PT), supraorbital (SO), supraorbital with orbital osteotomy (SOO) approaches, and endoscopic endonasal transplanum approach (EEA) were performed on 10 embalmed heads. The navigation system was used to measure the surgical exposure and freedom, including distance exposure of A1, A2, surgical area, horizontal, and vertical attack angles. The superior exposure of ACoA complex was calculated using the surrounding 3 points—the coordinate of the furthest right A1, the coordinate of the furthest left A1, and the midpoint between the left and right A2s. Inferior exposure also involved 3 points—again, the coordinate of the furthest right A1, the coordinate of the furthest left A1, and the anterior potion of the optic chiasm. The possibility of clipping the right and left A1 and A2 was assessed in all approaches; in each approach, the greatest distance of clipping (from the A1-ACoA-A2 junction to the aneurysm clip) was measured whenever it was feasible. A one-way ANOVA test was used to compare the means of the various parametric variables. Additionally, with this data, we considered a p-value of less than or equal to 0.05 as statistically significant.

Result:: There was a significantly longer distance in right A1 exposure in the PT (12.20 ± 2.48 mm) approaches when compared to the EEA (9.52 ± 2.09 mm, p = 0.029). The EEA has the shortest distance for right A1 clipping (6.56 ± 1.33 mm, p = 0.001) in four approaches. Additionally, EEA had the longest clipping distance in the right A2 (4.94 ± 0.90 mm) when compared to the other three microscopic approaches (p = 0.03). The EEA (50.90 ± 17.45 mm²) had more exposure area in superior part of ACoA complex than SO (29.37 ± 17.27 mm², p = 0.05). The PT (36.88 ± 5.85 degrees) provided the greatest horizontal angle of attack, while SOO (19.37 ± 4.7 degrees) achieved the greatest vertical angle of attack.

Conclusion:: The SO, SOO, and PT approaches provided parasagittal exposure of the ACoA complex, while EEA provided direct axial exposure of the complex. EEA can better expose the upper part of ACoA complex with relative limit surgical freedom. EEA appears to be a feasible alternative to treating select aneurysms with anterior and superior project of the ACoA complex.