Endoscopic Endonasal Approaches to the Clivus with No Violation of the Nasopharynx: Surgical Anatomy and Clinical Illustration

Background: Despite the use of vascularized intranasal flaps, endoscopic endonasal posterior fossa defects remain surgically challenging with high rates of postoperative CSF leak. The aim of this study is to describe a novel surgical technique that allows complete drilling of the clivus and exposure of the craniovertebral junction with preservation of the nasopharynx.

Methods: Two formalin-fixed latex-injected anatomical specimens were used to confirm feasibility of the technique. Karl-Storz (Tuttlingen, Germany) instruments were used for dissection including a 0- and 30-degree endoscopes and HD camera. Two surgical approaches were used: sole endoscopic endonasal approach and transnasion approach. Main endonasal surgical steps included: right-side nasoseptal flap harvesting, sphenoid rostrum exposure, vomer removal, sphenoid floor drilling, while preserving the roof of the nasopharynx, middle and inferior clivus drilling, bilateral maxillary antrostomies, removal of the orbital and sphenoid processes of the palatine bone, transection of the palatovaginal canal contents, lateral drilling of the pterygoid base and the sphenoid floor toward the vidian canal, bilateral transection of the fibrous attachment between the eustachian tube and the foramen lacerum, and foramen magnum drilling with lateral exposure of the jugular tubercle, hypoglossal canal, and occipital condyle ([Fig. 1]). The transnasion approach included: a Draf's III frontal sinusotomy with bilateral ethmoidectomies, a skin-crease transnasion horizontal incision, 1 cm × 2 cm transfrontal osteotomy, C1 arch drilling and reconstruction with the nasoseptal flap ([Fig. 2]).

The surgical technique of sole endonasal approach was used in a patient with a recurrent petroclival meningioma, treated previously with two lateral microscopic approaches. The tumor did not reach the foramen magnum, so the bone opening was extended inferiorly leaving a 3-mm rim of the inferior border of the clivus ([Fig. 3]).

Results: In both anatomical dissections, the inferior clivectomy with exposure of the foramen magnum was achieved with a sole endoscopic endonasal approach with preservation of the nasopharynx. The addition of the transnasion approach helped with the complete drilling of the inferior border of the foramen magnum and exposure of the arch of C1. No major limitation of maneuverability of the instruments through the nasion window was noticed.

The illustrative case showed the clinical application of this technique. There was no limitation exposing the inferior border of the tumor and its resection. A near total clivectomy was accomplished with preservation of the nasopharynx. In this case, there was no need to perform the transnasion approach since the tumor did not extend to the foramen magnum. Since the nasopharyngeal defect was avoided, there was no need for an extended nasoseptal flap for reconstruction. The patient was discharged with no postoperative CSF leak.

Conclusion: This study shows the anatomical feasibility of a novel surgical approach to accomplish a total clivectomy and exposure of the craniovertebral junction with preservation of the nasopharynx. A more favorable anatomical posterior fossa defect for the reconstruction is achieved with this technique. Further clinical studies are needed to assess if this change of the posterior fossa defect would impact the postoperative CSF leak rate of such challenging reconstructions.

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Publication History

Article published online:
12 February 2021