Using the Endoscopic Endonasal Transclival Approach to Access AICA, PICA, and Vertebral Artery: A New Surgical Approach for Clipping these Intracranial Aneurysms

Background: The endoscopic endonasal approach is a minimally invasive approach that provides direct access to the midline structures of the skull base. This approach has been used for the treatment of different pathologies, such as skull-based tumor and pituitary tumor resection. In the recent years, this approach has been successfully utilized for the clipping of cerebral aneurysms.

Objective: The purpose of this study was to explore the use of the endoscopic endonasal transclival approach for clipping aneurysms arising from the anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery (PICA), and vertebral artery (VA).

Methods: A total of 15 adult cadaver heads injected with dyed latex were dissected using the endoscopic endonasal transclival approach to assess the visualization of the arteries afforded by the approach. The length of each artery exposed and the distance from the bottom of the nares to the arteries were measured. Clips were placed on the arteries to demonstrate its feasibility with this approach.

Results: Both right and left AICA were exposed in all of the heads, with an average exposed length of 1.1 ± 0.3 cm and 0.8 ± 0.3 cm, respectively. The average distance from the nares to the origin of the right AICA was 10.3 ± 0.8 cm and to the origin of the left AICA was 10.3 ± 0.8 cm. The right PICA was exposed in 73.3% of the heads for a length of 0.5 ± 0.2 cm. Its origin was 10.9 ± 0.5 cm away from the nares. The left PICA was exposed in 80% of the heads for a length of 0.5 ± 0.2 cm and its origin was 11.1 ± 0.9 cm away from the nares. The right and left VA were exposed in 100% of the heads for an average length of 1.7 ± 0.6 cm and 1.6 ± 0.6 cm, respectively. The distance from the nares to the vertebrobasilar junction was 10.3 ± 0.7 cm. The distance from the nares to the lowest level of the right VA was 11.1 ± 0.9 cm and to the lowest level of the left VA was 11.1 ± 0.8 cm.

Conclusion: The endoscopic endonasal transclival approach can provide direct access to AICA, PICA, and VA, making it an appealing alternative to the traditional lateral occipital, far lateral, and retrosigmoid approaches for the clipping of aneurysms arising from those arteries. This approach allows for avoidance of manipulating the brain and cranial nerves, thus significantly reducing the postoperative cranial nerve palsies associated with the traditional approaches. The major disadvantage from using this approach is the high incidence of postoperative CSF leak; however, the adoption of nasoseptal and secondary flaps has greatly reduced the incidence of CSF leak. The endoscopic endonasal transclival approach should be considered for the surgical clipping of AICA, PICA, and VA aneurysms whenever standard treatments are deemed to be too risky or fail.