The Application of an “In Situ Bone Flap” in Skull Base Reconstruction after Extended Endoscopic Endonasal Approaches for Craniopharyngioma

Objective: This study aims to describe and evaluate a rigid skull base reconstruction method of using an “in situ bone flap (ISBF)” after extended endoscopic endonasal approaches (EEEAs) for craniopharyngioma.

Background: EEEAs for craniopharyngioma cause large skull base bone defects with an open cistern/ventricle, resulting in high-flow cerebrospinal fluid (CSF) leaks intraoperatively. The vascularized pedicled nasoseptal flap (PNSF) is the best method for reconstruction of skull base soft tissue at present. However, no reliable method exists for repairing bone defects repair after EEEAs.

Methods: We describe the ISBF for cranial base repairs in EEEAs. In all 116 cases of craniopharyngioma patients who underwent EEEA at the First Affiliated Hospital of Chongqing Medical University between January 2017 and June 2019. The skull base repair was performed using an ISBF in comparison to repairs in the initial period without an ISBF. The clinical outcomes of these methods were compared.

Results: Among the latter repairs with an ISBF, the postoperative CSF leak rate was 1.82% (1/55), reflecting a significant improvement compared with those (7/61, 11.5%) repairs without ISBF (p < 0.05). The follow-up CT images revealed good bone healing in the surgical region, and no neurovascular complications were observed.

Conclusion: A craniotomy-harvested ISBF for skull base reconstruction is feasible and safe in EEEAs. The ISBF combined with PNSF may further decrease postoperative CSF leaks and restore skull base anatomical structures postoperatively.