Multi-Layer Reconstruction of the Endonasal Skull Base without a Autografts or a Rigid Buttress

Background: The two most important developments in post-operative repair of the endonasal skull base have been the introduction of the nasoseptal vascular flap 3 and the gasket-seal closures. 5. We have previously described a one-piece modified gasket seal technique to achieve a watertight closure. 6 This reconstruction is built around autologous fascia sutured to a porous high-density polyethylene plate to serve as a rigid buttress. In light of reports which omit a rigid buttress 1,2,4, we recently switched to an inlay/onlay reconstruction technique utilizing off-the-shelf dermal allograft. Our technique omits autologous fat graft, fascia and a rigid buttress. We hypothesized that this would be equally safe and effective, while offering potential savings in time and donor site morbidity.

Surgical Technique: Reconstruction of the skull base defect begins with an absorbable lyophilized collagen inlay followed by a human cadaveric dermis allograft onlay. A pedicled nasoseptal flap provides the final layer of closure. Woven oxidized cellulose and fibrin glue are used to secure the edges of the nasoseptal flap. This is then externally buttressed with absorbable fragment able polyurethane foam, as previously described. 6

Methods: We retrospectively reviewed our prospectively collected, IRB approved database to identify all patients who underwent expanded endonasal approaches from 2011 to 2015. Patient demographics, tumor pathology, type of reconstruction, incidence of post-operative CSF leak, and total operative time, development of donor site morbidity and cost of graft materials were reviewed.

Results: A total of seventeen patients were identified. Twelve patients had modified gasket seal reconstruction (six meningiomas and six craniopharyngiomas) and five (all meningiomas) had inlay/onlay reconstruction. External CSF drainage was utilized in all patients. CSF was diverted for an average of 6.8 days (range 1–13 days) in the gasket-seal group versus 5.8 days (range 5–6 days) in the inlay/onlay group. This difference was more pronounced (7.2 vs 5.8 days respectively) when examining the subsets of meningiomas. In the gasket-seal group, we took three patients (25%) back to the OR for a second-look between days 5–7, with one persistent post-operative CSF leak requiring surgical repair (8.3%). There was one patient (20%) in the inlay/onlay group taken back to OR for a second-look, with no persistent leak identified (0%). Mean operative time was 422 minute (gasket-seal) versus 364 minute (inlay/onlay). Again, this difference was more pronounced (534 minute vs 364 minute) when examining meningiomas only. The total cost of off the shelf implants was $113 less in the inlay/onlay group.

Conclusion: Our data add to the growing body of evidence that a rigid buttress may not be necessary in effective reconstruction of the ventral skull base. The inlay/onlay technique is non-inferior to modified gasket-seal closure for preventing CSF leak. There is an overall savings of at least 60 minutes in total operative time, patients are spared donor site morbidity, and experience at least 1 fewer day of CSF diversion. There is a total cost savings as a result of both lower implant costs, shorter OR times, fewer returns to OR, and lower overall ICU stays.