In-situ bone flap combined with a nasoseptal flap or a free mucosa flap for skull base reconstruction after endoscopic resection of craniopharyngiomas: A series of 115 cases

Previous reports have indicated that in comparison with the use of a nasal septal flap (NSF) for skull base reconstruction, the use of a free mucosal flap (FMF) is associated with an increased incidence of cerebrospinal fluid (CSF) leakage in patients with intraoperative high-flow CSF leakage but less nasal trauma. The authors previously reported that the use of an in situ bone flap (ISBF) was beneficial for controlling postoperative CSF leakage. The objective of this study was twofold. The first aim was to analyze the risk factors associated with postoperative CSF leakage. Second, the CSF leakage rate was compared between the two reconstruction techniques for different risk factors and total Sino-Nasal Outcome Test-20 (SNOT-20) scores. The results verify the feasibility of the use of an ISBF combined with an FMF for skull base reconstruction to control postoperative CSF leakage. Furthermore, the findings clarify the choice of skull base reconstruction in different situations. A retrospective review of 115 patients with craniopharyngiomas treated between May 2018 and June 2022 was conducted. Reconstruction of the skull base was performed in 67 patients using a combination of ISBF and NSF by October 2020 and in 48 patients using a combination of ISBF and FMF after October 2020. The overall rate of postoperative CSF leakage was 8.7%. According to the univariate analysis, a BMI ≥ 25 (20.7% vs. 4.9%, p = 0.016) and predominantly solid tumors (15.1% vs. 3.2%, p = 0.042) were associated with higher rates of postoperative CSF leakage. In the multivariate analysis, a BMI ≥ 25 and a solid component > 50% were identified as independent risk factors for postoperative CSF leakage. The mean SNOT-20 score was lower in the ISBF + FMF group than in the ISBF + NSF group at six months after surgery (13 ± 12.7 vs. 16 ± 16, p = 0.037). With respect to the repair of skull base defects by using the ISBF, the application of FMF controlled the postoperative CSF leakage rate within an acceptable range. Furthermore, it offered advantages over NSF in terms of SNOT-20 scores at six months post-operatively. A BMI ≥ 25 and a solid component > 50% were independent risk factors for postoperative CSF leakage. NSF remains a more suitable option for patients with a BMI ≥ 25.