Anchoring the Anterior Margin of the Dural Inlay Graft: A Technical Note on Endoscopic Anterior Skull Base Reconstruction

Introduction: The endoscopic endonasal corridor has been increasingly utilized for anterior skull base (ASB) lesions. In cases requiring large endoscopic ASB resection, postoperative cerebrospinal fluid (CSF) leak is a feared complication. The anterior margin of the defect is the most problematic for endoscopic endonasal reconstruction given the limited amount of bone available for adequate flap apposition. Thus, with the aim of strengthening ASB reconstruction, we studied the feasibility of mechanically anchoring a free fascia graft inlay to the posterior table of the frontal sinus.

Methods: Four formalin-fixed, latex-injected head specimens were dissected to assess the feasibility of reconstruction of a large ASB defect with an anteriorly anchored intradural inlay temporalis fascia graft. In this cadaveric study, temporalis fascia was utilized to mimic fascia lata, the most utilized inlay graft, because of its availability in the cadaveric head specimen. After a Draf III frontal sinusotomy, a wide transplanum–transcribriform approach was performed, and the crista galli was removed. The dura was resected within the margins of the ASB osteotomy, exposing the corresponding intracranial structures.

Results: Four holes were endoscopically drilled in the posterior table of the frontal sinus with no violation of the underlying dura. The holes were drilled 0.5 cm anterior to the anterior margin of the osteotomy. 3–0 silk sutures, each with needles at both ends, were passed through the holes from the frontal sinus to the intracranial space. The needles entered through the patient's left nostril and exited through the right nostril. The needles on the right side were used to suture the anterior edge of the fascial graft at a distance that approximated the distance of the holes in the posterior table of the frontal sinus. Those needles were then severed, and the graft was carefully placed into the nasal cavity through the right nostril. During this process, gradual traction was applied on the portion of the sutures passing through the left nostril. This allowed the anterior edge of the graft to be successfully tucked intradurally against the intracranial surface of the posterior table of the frontal sinus. To provide a buffer for the ASB during tightening of the sutures, muscle pledgets were placed through each needle exiting the left nostril, and each pledget was slid up the suture to meet the extracranial surface of the ASB. The needles were severed, and the four sutures were tied, two sutures to each other. No gap was present at the anterior margin of the ASB defect after the sutures were secured.

Conclusions: Anchoring the free graft inlay to the posterior table of the frontal sinus is a technically feasible method of securing a fascial inlay in a commonly unstable portion of ASB reconstruction ([Figs. 1] [2] [3] [4]).

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Artikel online veröffentlicht:
01. Februar 2023