Bilateral Mucosal and Septal Olfactory Strip (SOS) Preserving “Rescue” Flaps: A Novel Vascular Pedicle Saving Technique for Endonasal Endoscopic Skull Base Surgery

Background: The Hadad-Bassagasteguy nasoseptal flap (NSF) has reduced the incidence of postoperative cerebrospinal fluid (CSF) leaks in endonasal endoscopic skull base surgery. However, in our experience, although an NSF is typically used in extended approaches with a large dural opening and a grade 3 CSF leak, it is rarely needed for smaller dural defects (grades 1 and 2 CSF leaks) encountered in the removal of more common sellar lesions such as pituitary adenomas and Rathke’s cleft cysts. In the traditional endonasal approach, the vascular pedicle that would supply an NSF is sometimes sacrificed during the sphenoidotomy, thus eliminating the flap as a potential reconstruction option should a large CSF leak be encountered. A unilateral “rescue” flap, preserving the sphenopalatine artery on one side, which allows it to be available for the potential elevation of an NSF should it become necessary, has previously been described. In this series, we introduce the concept of bilateral mucosal and septal olfactory strip (SOS) preserving “rescue” flaps for use in the majority of endonasal endoscopic cases in which an NSF is not expected to be needed. In addition to protecting the bilateral vascular pedicles for future use, this technique also preserves more nasal-septal mucosa including the bilateral septal olfactory strip (SOS flap), promotes more rapid healing, and potentially reduces the incidence of postoperative sphenopalatine artery epistaxis and anosmia.

Methods: A retrospective analysis was performed of all patients at our institution who underwent endonasal endoscopic surgery with the elevation of bilateral nasoseptal “rescue” flaps during the initial approach.

Results: Seventy-one patients were identified. These included 59 pituitary adenomas (17 functional, 42 nonfunctional), 6 Rathke’s cleft cysts, 3 sellar metastases, 1 meningioma, 1 fibrous dysplasia, and 1 B-cell lymphoma. Eighteen tumors had suprasellar and/or parasellar extension, whereas 28 had some degree of cavernous sinus invasion. Excellent visualization and mobility of the endoscope, suction, and dissecting instruments were experienced in all cases. There were no limitations of access to the sphenoid, sellar, suprasellar, cavernous, or optic canal region. One patient underwent conversion to a formal NSF without complication. No patients experienced postoperative arterial epistaxis. Outpatient debridements were performed on or around postoperative days 10, 24, and 38. Faster healing times and diminished nasal crusting was noted, with full mucosalization typically occurring by 6 weeks after surgery.

Conclusions: The bilateral nasoseptal “rescue” flap technique is an effective mucosal-sparing approach, applicable for the majority of endonasal endoscopic tumor resections, that maintains both the vascular pedicle of the formal NSF and the SOS. This anatomical and physiologic approach likely reduces or potentially eliminates the risk of major postoperative epistaxis, specifically those originating from the transected sphenopalatine artery; preserves olfaction; and promotes rapid nasal mucosal healing while not hindering exposure or limiting instrument maneuverability. A detailed investigation on the degree of olfactory preservation and rate of postoperative epistaxis occurring with this technique is currently underway.