Optic Canal Unroofing Extends the Lateral Reach in Endoscopic Transnasal Surgery for Suprasellar Lesions

Background: Although endoscopic transnasal surgery (ETS) is a well-established minimally invasive treatment option for suprasellar/parasellar lesions, its lateral reach is limited. Optic canal (OC) and internal carotid artery (ICA) are significant obstacles determining the lateral limit when performing ETS; thus, accessing lesions with lateral extension beyond them remains a considerable challenge. This study reviews the effect of OC unroofing on surgical outcomes and patient safety.

Methods: Among the consecutive 196 ETS cases between June 2021 and June 2024, transplanum/tubercular approach was used in 47 cases either solely or in conjunction with the other approaches. Of them, those who had tumors with significant supra-OC extension (> 3-mm lateral to the medial edge of the OC) and supra-ICA extension (> 3-mm lateral to the medial edge of the ICA) were retrospectively studied. After exposing the ventral skull base, the dura of the proximal OC and upper part of the carotid siphon as well as the planum sphenoidale were adequately exposed. The roof of the OC, a small triangular pyramid-shape bone, was then removed using a 2- or 3-mm diamond drill and fine bone punches to gain lateral reach. A 30-degree endoscope was utilized to fully visualize the lateral tumor parts.

Results: [Figs. 1] and [2] demonstrate a representative case. Nineteen patients (13 meningiomas, 2 pituitary neuroendocrine tumors, and 4 miscellaneous tumors) were included. Among 8 tumors with supra-OC extension, the mean distance from the medial OC edge to the lateral tumor margin was 6.9 mm (range, 4.8–8.7 mm). Complete removal was confirmed in all of them. Among 18 tumors with supra-ICA extension, the mean distance from the medial ICA edge to the lateral tumor margin was 9.1 mm (range, 5.0–17.2 mm). Complete removal was confirmed in all but 3; the mean maximal reach was 7.8 mm (range, 5.0–14.4 mm). Visual impairment was improved in all the nine patients with preoperative deficit; no postoperative visual deterioration was observed in any of the patients. One patient required a burr hole surgery for chronic subdural hematoma, one developed meningitis which required prolonged antibiotics, and one had postoperative cerebrospinal fluid leakage requiring surgical repair.

Conclusion: Optic canal unroofing is a simple technical modification that can be easily incorporated if needed, and contributes to extend the lateral reach up to 9 mm from the medial OC edge and 14 mm from the medial ICA edge without causing visual deficit.

Fig. 1 A case of tuberclum sellae meningioma with lateral extension (A, preoperative MRI showing supra-OC tumor extension [yellow arrowhead]), which was removed through ETS (B, postoperative MRI). During the ETS, the roof of the OC (cyan triangle and asterisk in C) was removed (D) to allow for visualization of the supra-OC tumor (E). This was completely removed at the end (F, yellow dotted circle indicates the location of the supra-OC tumor).

Fig. 2 The three-dimensional simulations are shown. The roof of the OC is highlighted in cyan (left image), behind which the supra-OC tumor (purple) is located (middle image). The right image shows a view from above.

Publication History

Article published online:
07 February 2025