Reconstructive outcome of intraoperative cerebrospinal fluid leak after endoscopic endonasal surgery for tumors involving skull base

•We assessed the repair outcome for CSF leak after transnasal endoscopic surgery for non-pituitary skull base tumors.•Postoperative CSF leaks occurred in 14 of 100 patients (14.0%) after endoscopic transnasal surgery for skull base tumors.•Repair failure after endoscopic transnasal surgery for skull base tumors remained challenging. Endoscopic transnasal surgery for tumors located at the base of the skull has a high incidence of postoperative cerebrospinal fluid (CSF) leaks. Here, we assessed the repair outcomes for high-flow CSF leaks based upon the tumor location, and analyzed the reasons for repair failure after transnasal endoscopic surgery solely for tumors involving the base of the skull. From Feb. 2009 to Dec. 2014 we performed endoscopic endonasal surgery for a variety of skull base lesions in 788 patients at our institution. Among them, 95 patients with intradural skull base tumors underwent endoscopic transnasal surgery. We performed surgical repairs with a multilayered nonvascularized construct (38 patients) and a vascularized pedicled nasoseptal flap construct combined with a fascia graft (57 patients). Overall, 14 of 95 patients (14.7%) who underwent endoscopic transnasal surgery for skull base tumors developed postoperative CSF leaks. The major causes of repair failure included graft disruption by a lack of counter-pressure in the multilayered non-vascularized technique, and inadequate drilling of the sphenoid bone, displacement of the flap due to pressure from CSF or gravity, or disruption of flap integrity in the vascularized pedicled flap technique. Logistic regression analysis revealed that there was no significant association between repair failure and age, sex, type of reconstructive method used, and primary tumor type (p>0.05). Reconstruction after endoscopic endonasal surgery remained challenging, especially for non-pituitary skull base tumors requiring intra-arachnoidal dissection. Recent advances in reconstructive techniques require the accumulation of experiences with sufficient dexterity to achieve an acceptable morbidity rate.