Learning curve and technical nuances of endoscopic skull base reconstruction with nasoseptal flap to control high-flow cerebrospinal fluid leakage: reconstruction after endoscopic skull base surgery other than pituitary surgery

Purpose Although reconstruction techniques after endoscopic skull base surgery have been improved, there are difficulties in reconstructing the skull base with a nasoseptal flap (NSF), especially in the case of high-flow cerebrospinal fluid (CSF) leak. The aim of this study was to analyze risk factors for the development of postoperative CSF leaks in terms of less experienced surgeon practices. Methods Retrospective review of medical records was performed for 125 patients who underwent endoscopic skull base surgery for intradural pathology with intraoperative high-flow CSF leakage between Oct 2012 and Apr 2017. Basic demographic data were collected, including body mass index (BMI), tumor pathology, comorbidities, and outcomes. To assess the learning curve effect, patients were divided into early cohort ( n = 30) and late cohort ( n = 95) groups. Results Overall postoperative CSF leakage was 10.4% (13/125) in this series. There were no significant risk factors for postoperative CSF leakage among the demographic data including BMI, comorbidities, or radiation history. Postoperative CSF leakage was most prevalent in the transclival approach than in other approaches, but the difference was not statistically significant (20.8%, p = 0.351). When dividing the results by timetable, the patients who underwent skull base reconstruction in the early cohort experienced more postoperative CSF leakage (23.3%, 7 cases out of 30) than in the late cohort (6.3%, 6 cases out of 95, p = 0.014). The learning curve was steeper in the early cohort (30 early cases 23.3%, 31–60 10%, 61–90 6.7%, 91–125 2.9%). Conclusions To improve the success rate of endoscopic skull base reconstruction, surgeons have to keep the basic technical details in mind to reduce the learning curve.