Alternative Path for Optic Nerve Decompression in Pseudotumor Cerebri With Full Endoscopic Lateral Transorbital Approach.

ABSTRACT

Endonasal endoscopic approaches are the most preferred surgical methods in patients with pseudotumor cerebri because of easy access to the optic nerve, but the choice of this technique may not apply to all endoscopic endonasal cases. Moreover, there may be difficulties in practice in some cases, including the coronavirus disease 2019 pandemic. This study aimed to suggest an alternative endoscopic approach by lateral orbitotomy for optic nerve decompression in patients with pseudotumor cerebri. The study was performed using 5 fresh-frozen cadaver heads (bilaterally, total of 10 sides) injected intravenously with colored silicone preserved in the cold chain. An average of 2.5 cm skin incision was made to fit the lateral orbitotomy. The lengths of the recurrent meningeal artery (mm), the meningo-orbital band (mm), and the optic nerve (mm) to the orbital margin were measured. After these morphometric measurements, optic nerve decompression was performed endoscopically, and the length of the decompression was measured (mm). The average length (mm) between the orbital rim and meningeal recurrent artery (or meningolacrimal branch) was 16.2 mm, between the orbital rim and the meningo-orbital band was 18.5 mm, and between the orbital rim and optic nerve was 44.1 mm. The average optic nerve decompression length was 4.4 mm. The endoscopic lateral orbitotomy approach provides easy access to the optic nerve by anatomically following the recurrent meningeal artery and the meningo-orbital band. It can be a safe second-line approach after endonasal approaches for optic nerve decompression in pseudotumor cerebri.