A New Vascularized Flap for Cranial Base Reconstruction: The Posterior Septal Nasal Floor Mucosal Flap

Objective: While pedicled intranasal flaps, such as the nasoseptal flap (NSF) successfully reduce postoperative CSF leaks following endoscopic endonasal approaches (EEA) to the skull base, local morbidity arising from denuded area donor site can impact quality of life. Given success with the nasal floor free mucosal graft (FMG) in place of the NSF, there is a question of whether the mucosal floor could undergo transformation into a pedicled flap, harnessing the robust blood supply of the posterior septal artery (PSA) while avoiding the morbidity that comes with the traditional NSF. This study describes the first anatomical description of the posterior septal nasal floor mucosal flap (PSNF) in a cadaver dissection and our experience in the first series of recipient patients for reconstruction of a sellar or suprasellar defect.

Methods: Seven cadaver specimen heads underwent harvest of the PSNF. Cadavers were injected with colored latex to aid in visualization of the arterial and venous vascularity within the sinus. Following flap elevation, the PSNF was placed into a created sellar defect. Flap dimensions were measured from several of the specimens. We additionally performed a retrospective chart review on the first set of patients who received the PSNF for reconstruction of a sellar or suprasellar base defect. Indocyanine green (ICG)-enhanced fluorescence was used to visualize the vascularization of the flap. Information concerning complications, symptoms, and the appearance of the flap (if visualized) was recorded from records of the patient's post-operative inpatient stay, 1-week post-op visit, and 1-month post-op visit.

Results: Cadaver dissection of the PSNF flap demonstrated good arc rotation along its pedicle following complete dissection off the septum, nasal floor, and lateral nasal wall ([Fig. 1A]). With rotation into the created defect, the flap demonstrated the ability to completely cover the sellae, exposed bilateral opticocarotid recesses, and a significant portion of exposed planum ([Fig. 1B, C]). Measurements obtained from the harvested flap demonstrated a mean length across the flap of 5 cm (range: 4.7–5.8 cm), a mean height of 3.3 cm (range: 3–3.7 cm), making for a mean area of 16.7 cm². Thirteen patients underwent reconstruction of a sellar defect using the PSNF technique. A CSF leak was present intraoperatively in approximately half of cases. The PSNF flap was able to cover the created sellar defect in all cases without need of a rescue flap. ICG demonstrated robust vascularization of the flap in its final location over the defect ([Fig. 2]). No intraoperative or post-operative complications were encountered. Examination of the flap at the 1 month visit in patients revealed a well healing flap with complete/near complete remucosalization of the nasal floor donor site ([Fig. 3]).

Conclusion: The PSNF flap is a novel pedicled flap that can be applied for the reconstruction of sellar and suprasellar defects in the presence of CSF leaks. This technique appears to provide a sizeable pedicled region for reconstruction comparable to other pedicled nasal flaps. Our case series demonstrated good post-operative outcomes without reduced donor site morbidity.