Infraorbital nerve as effective intraoperative guidance during the endoscopic transorbital approach to the anterolateral skull base.

Objective: The endoscopic transorbital approach (ETOA) has been recognized as a pivotal technique within the realm of endoscopic skull base surgery for the management of lesions situated in the skull base with paramedian and lateral positioning. In the execution of the ETOA targeting the anterolateral skull base, the surgical intervention is performed in the coronal plane from superficial to deep with the anatomy becoming progressively more complex. Given that the trajectory of the infraorbital nerve (ION) algins favorably with the surgical corridor of the ETOA to the anterolateral skull base, this investigation evaluates the feasibility of employing the ION as an intraoperative navigational aid during the ETOA, utilizing both cadaveric dissection and relevant clinical applications.

Methods: Anatomical dissections were conducted on five adult cadaveric heads bilaterally utilizing two distinct endoscopic transmaxillary techniques aimed at the anterolateral skull base, namely the ETOA and the endoscopic endonasal approach (EEA). For each technique, the anatomical interrelationship between the ION and the adjacent compartments of the anterolateral skull base was meticulously documented. Additionally, the extent of ION exposure was systemically compared between the ETOA and EEA methodologies. The clinical practicality of cadaveric findings was evaluated in two patients presenting with deeply seated neoplasm located in the anterolateral skull base.

Results: In contrast to the EEA, the ETOA demonstrated a markedly greater exposure of the orbitomaxillary segment (ETOA = 32.10 ± 3.32 mm; EEA = 9.98 ± 2.23 mm; P <.001) and the cavernous segment (ETOA = 14.61 ± 1.24 mm; EEA = 8.7 ± 3.72 mm; P <.001) of the ION. Both approaches exhibited a comparable extent of exposure concerning the pterygopalatine segment of the ION (ETOA: 10.66 ± 1.39 mm; EEA: 9.98 ± 2.23 mm). In both cases where patients underwent treatment via the ETOA with the ION utilized as intraoperative navigation, complete tumor resection was achieved without any occurrence of neurological or ophthalmic complications.

Conclusions: According to the findings derived from cadaveric studies and the preliminary clinical implementations, the ION serves as a dependable intraoperative navigational tool throughout the ETOA toward the anterolateral skull base. Each distinct segment of the ION is capable of guiding the operator safely towards the deeper segment and more profound complex anatomy.