Surgical Experience and Validation of the "Bow Tie" Trilayer Graft Technique for Closure of Anterior Skull Base Defects.

Objectives: Multiple reconstruction techniques exist to repair defects arising from expanded endonasal approach (EEA) surgeries targeting anterior skull base tumors. These repairs aim to minimize post-operative complications such as cerebrospinal fluid (CSF) leak. In 2022, our group described the "Bow tie" trilayer graft, a repair method that incorporates two layers of a collagen matrix graft stitched to a fat graft. The initial data demonstrated a reduction in the rate of CSF leaks following the adoption of this method. This study evaluates the surgical practice of a single surgeon with access to the trilayer technique and the post-operative outcomes. Methods: Retrospective chart review encompassing all EEAs to anterior skull base tumors performed by a single otolaryngologist (JGG) from January 2019 to September 2024 at a tertiary care center. Results: Of 250 cases meeting inclusion criteria, 42 (16.8%) involved bow tie graft reconstruction. Postoperative CSF leaks occurred in 3 subjects (1.2%), with none of these cases involving bow tie grafts. Trilayer grafts were used more frequently in revision cases (p = 0.018) and when intra-operative CSF leaks were encountered (p < 0.0001). There was no difference in average age, sex, BMI, maximum tumor dimension, or the frequency of lumbar drain insertion between the groups with and without trilayer grafts (p > 0.05). Conclusion: The trilayer graft is an efficient and useful tool in the armamentarium of an anterior skull base surgeon. This technique may decrease rates of postoperative CSF leak with limited additional morbidity. Larger multicenter studies are warranted to validate this potential benefit given the relative rarity of this complication. Level of Evidence: 4.