Closure of skull base defects after endoscopic endonasal transsphenoidal surgery: the role of the local sphenoid mucosal flap for low flow leaks

A local sphenoid mucosal flap (SMF) is naturally raised during endonasal exposure of the sella. Typically, these flaps are repositioned; however, they could be used in place of a nasoseptal flap (NSF) for closure of low-grade CSF leaks. In this study, we aim to establish the safety and efficacy of SMF closure for low-grade CSF leaks and to assess the impact on sinonasal quality of life (QoL) compared to NSF closure. In a consecutive, prospective cohort of anterior skull base pathology, data regarding sellar and suprasellar extension (Hardy grade), cavernous sinus invasion (Knosp grade), intraoperative (Kelly grade) and postoperative CSF leak, and sino-nasal QoL data (SNOT-22) were analysed. Of 187 patients with no/low flow (Kelly 0-1) intraoperative CSF leak, 127 (67.9%) received a SMF and 60 (32.1%) received a NSF. A total of 141/187 (75.4%) had no intraoperative leak, while 46/187 (24.6%) had grade-1 leaks. SMF were used in 70.9% (100/141) of cases without intraoperative leak, and 58.7% (27/46) of cases with Kelly grade-1 leaks. Hardy grade 4, grade E and Knosp grade 4 lesions were all more commonly closed with a NSF (p < 0.05). Two patients (1.1%) had postoperative CSF leaks, both in the SMF group, and both after no discernible intraoperative leak. Sinonasal QoL was below baseline for up to 3 months postoperatively. SMF cases tended to have better sinonasal QoL for up to 6 weeks after surgery. Thus, in the largest cohort to date, SMF are a safe alternative to NSF for closure low-grade skull base defects. Sinonasal QoL was better in the first 6 weeks after SMF closure than NSF closure.