Endoscopic optic nerve decompression through supraorbital keyhole extradural approach: a cadaveric study

larger trauma from the craniotomy procedure may hinder the patients to accept the approach.The endoscopic transnasal approach has an advantage of minimal invasion, but the narrow surgical corridor and potential severe bleeding reduce the popularity of the approach.For the supraorbital keyhole operation, a small incision located in the unilateral eyebrow is made and the sellar region can be reached through the intracranial natural space.Enlightened by the keyhole idea and with the aim to decrease the corresponding invasion of the conventional approaches, we tried to design a novel endoscopic approach to achieve an █ InTRODuCTIOn M any surgical approaches have been described for decompression of the optic nerve to treat traumatic optic neuropathy (14,18,21,22).The most commonly used approaches include the transcranial and the transnasal approaches (15), and each of them has specific advantages and disadvantages.The conventional transcranial approach can enable a direct access and sufficient exposure to the superior wall of the optic canal, which could help achieve an effective decompression of the optic nerve.However, the AIM: Many approaches for optic nerve decompression have their own advantages and disadvantages.The aim of this study was to perform endoscopic decompression of optic nerve through the supraorbital keyhole and evaluate its feasibility. MATERIAL and METhODS:Ten adult cadaveric heads were studied using 4-mm, 0-and 30-degree rigid endoscopes to perform the optic nerve decompression through the supraorbital keyhole extradural approach.Furthermore, the relevant measurements about the optic canal were recorded. RESuLTS:Through the supraorbital keyhole, the endoscope was introduced into the extradural space, and the following structures could be exposed and identified: the sphenoid ridge, the anterior clinoid process, the roof of the optic canal and the falciform ligament.The roof and lateral wall of the optic canal were removed using a drill under the endoscope, and more sufficient decompression could be achieved by further incising the falciform ligament and optic sheath.After measurement, the distance from the zygomatic process of the frontal bone to the optic canal was 59.32 ± 2.27 mm, the distance from the upper midpoint of the posterior foramen of the optic canal to the internal carotid artery was 3.80 ± 0.93 mm. COnCLuSIOn:According to the cadaveric study, it is feasible to perform the endoscopic decompression of optic nerve with a clear view through the supraorbital keyhole extradural approach.Our study may provide a minimally invasive and safe option for the optic nerve decompression.