Formal Closure of Endoscopic Endonasal Skull Base Defects With a “Bow Tie” Tri‐Layer Graft

OBJECTIVE: Risk factors for a postoperative cerebrospinal fluid leak (CSF) after surgery include an intraoperative high flow of CSF, elevated body mass index, defect size, and defect site. In our prior series, a high postoperative CSF leak rate for tumors of the central skull base (planum, sella, and clivus) appeared to be due to graft migration. We changed our closure technique from a single layer of collagen +/- fat graft to a novel graft, termed a "Bow tie" (a tri-layer fat graft with two pieces of collagen matrix), and report our results in this study. METHODS: Retrospective temporal epoch study of a single otolaryngologist's experience of closing skull base defects in our skull base center from 2005 to 2017. RESULTS: One hundred and forty-nine patients met inclusion criteria in two time periods, pre- and post-introduction of the Bow tie technique. In epoch I, from 2005 to 2013, 79 patients had reconstruction with a single layer of dural graft (25 had additional free fat graft). In epoch II, from 2014 to 2017, 70 patients had reconstruction with the Bow tie. RESULTS: CSF leak rates were 8.7% overall: 15.2% in epoch I and 1.4% in epoch II (p = 0.01). After controlling the procedure, defects with a size greater than 2 cm had a 5.7 greater likelihood of failure. Epoch II had a lower incidence of major complications. CONCLUSION: Using a single surgeon's experience, the multilayer Bow tie has a significant reduction in postoperative CSF leak and associated major complications for defects of the central skull base. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:1568-1575, 2023.