Contralateral Nasoseptal Flap for Middle Cranial Fossa Defects After Osteoradionecrosis

Contralateral nasoseptal flaps are a valuable salvage option for reconstruction of large skull base defects when the ipsilateral pedicle is unavailable. We describe a reproducible step-by-step technique combining a contralateral Hadad–Bassagasteguy flap with a reverse-rotation septal mucosal flap for repair of middle cranial fossa defects. The approach is illustrated in a patient with skull base osteoradionecrosis and cerebrospinal fluid rhinorrhea. The vascular pedicled nasoseptal flap (Hadad–Bassagasteguy flap) has become the workhorse for endoscopic skull base reconstruction because of its robust vascularity, long arc of rotation, and ability to span from the frontal sinus to the lower clivus. However, prior surgery, radiation, or tumor involvement of the ipsilateral pterygopalatine and infratemporal fossae may limit its use or render ipsilateral dissection oncologically unsafe [1, 2]. Contralateral nasoseptal flaps have been described to extend the reach of vascularized septal mucosa when the ipsilateral pedicle is not available; however, most reports focus on specific skull base regions or small series and provide relatively limited technical detail. In this “How I Do It” article, we present our approach to reconstruction of middle cranial fossa defects using a contralateral nasoseptal flap combined with a reverse-rotation septal mucosal flap. A contralateral nasoseptal flap may be used for reconstruction of irradiated skull base defects when vascularized coverage is required, the ipsilateral nasoseptal pedicle is either unsafe or unavailable, and the contralateral septum together with its sphenopalatine artery remains sufficiently preserved to allow reliable flap elevation [3, 4]. The surgical technique can be viewed in the Video S1 and is described here. The procedure is performed endoscopically under general anesthesia. We use 0° and 45° endoscopes and standard endoscopic sinus and skull base instrumentation. Topical decongestion and infiltration with a vasoconstrictor-containing local anesthetic facilitate hemostasis and visualization. We begin in the ipsilateral (left) nasal cavity using a 0° endoscope. All mucopurulent and necrotic material is gently suctioned from the nasal cavity and maxillary sinus, particularly around the skull base defect. This step improves visualization and reduces bacterial load before reconstruction. A topical vasoconstrictor is applied using pledgets along the septum and lateral nasal wall. Local infiltration is then performed using lidocaine with epinephrine in the posterior septum and along the planned incision lines. In irradiated cases, injection volumes are minimized and delivered in a submucoperichondrial plane to reduce mucosal trauma while still improving hemostasis and visualization. To obtain a generous working corridor, we perform a middle turbinectomy and complete ethmoidectomy on the left side. All residual ethmoidal air cells and overlying mucosa that obstruct access to the posterior maxillary wall and skull base are removed. We then address the sphenoid rostrum. Using a suction–coagulation device, we cauterize and contour the sphenoid face to widen the approach and facilitate a later posterior septectomy. Because the patient's osteoradionecrosis and prior tumor involved the left infratemporal and pterygopalatine fossae, a standard ipsilateral nasoseptal flap was deemed unsafe and was not attempted. With the defect fully exposed, we perform meticulous debridement of all devitalized bone and necrotic soft tissue. Angled endoscopes and instruments (curettes, suction tips) are used to explore the full extent of the bony defect and dural exposure. Necrotic bone is curetted until healthy, bleeding margins are encountered. The superficial, devitalized layer of dura is carefully removed using angled Blakesley forceps to refresh the dural edges and remove fibrotic and necrotic tissue. The objective is a clean, well-defined defect with healthy dural and bony margins before flap placement (Figure 1A). We move to the contralateral (right) nasal cavity to harvest the nasoseptal flap. The sphenopalatine artery and its posterior nasal branches are identified and meticulously preserved. Using a long-tip monopolar cautery, we outline and elevate a Hadad-type nasoseptal flap following standard anterior, inferior, and superior incisions [2]. Once elevated, the flap is gently parked in the nasopharynx, ensuring that the pedicle remains intact and the flap appears well perfused, without signs of congestion. Parking the flap in the nasopharynx keeps it protected while the midline corridor is prepared (Figure 1B). Using the same monopolar instrument, a mucosal flap is elevated from the septal side opposite to the nasoseptal flap donor area. The flap is typically fashioned by performing a vertical septal incision at the level of the posterior septectomy, followed by a superior horizontal incision along the septal dorsum and an inferior horizontal incision parallel to the nasal floor, allowing posterior-to-anterior elevation of the mucoperichondrial and mucoperiosteal layer while preserving the anterior vascular pedicle. This reverse mucosal flap is intended to cover the denuded septal cartilage created by nasoseptal flap harvest, promoting remucosalization and reducing crusting. The flap is left attached but not yet fully rotated until the posterior septectomy is completed. To maximize the reach of the contralateral nasoseptal flap, we perform a wide posterior septectomy, removing a generous segment of the posterior nasal septum to create a broad transseptal window. Then, the sphenoid rostrum is drilled and any obstructing bony septations within the sphenoid sinus are removed. These maneuvers enlarge the corridor and effectively lengthen the flap's arc of rotation. Before transposition, we confirm that the flap remains well perfused, and that gentle stretching does not compromise the pedicle. We then complete the reconstruction of the donor septum. The reverse-rotation septal mucosal flap is rotated over the denuded contralateral septal cartilage. It is secured with two anterior absorbable sutures to prevent retraction. This flap hastens septal healing and reduces the area of bare cartilage, which decreases postoperative crusting and improves patient comfort [3]. The nasoseptal flap is then rotated from the nasopharynx into the left nasal cavity. Under 45° visualization and angled instruments, we carefully swing the flap across the posterior septectomy (Figure 1C). The flap is draped over the entire dural and bony defect, ensuring that it covers and slightly overlaps all margins of the osteoradionecrotic area. Particular attention is paid to avoiding kinking or undue tension on the pedicle; the flap should be stretched enough to lie flat but never tight. The flap is gently molded to conform to the contour of the middle cranial fossa defect. To buttress the reconstruction, resorbable hemostatic material (Surgicel; Ethicon Inc., Somerville, NJ, USA) is placed along the edges of the defect to support the mucosal–dural interface. A dural sealant (DuraSeal; Integra LifeSciences Corp., Princeton, NJ, USA) is applied over the flap to reduce the risk of postoperative CSF leak. The reconstructive complex is further supported with resorbable nasal packing (NasoPore; Stryker Corp., Portage, MI, USA), positioned to gently compress the flap against the middle cranial fossa defect. Finally, nasal splints are placed to protect the septal donor site and stabilize the flaps. Postoperative management is standardized to protect the flap pedicle, reduce crusting, and minimize infectious complications in the irradiated nasal cavity. Saline irrigations are typically initiated on postoperative day 3–5, once nasal packing is removed, and continued at least twice daily until complete remucosalization. Antibiotic treatment was granted with short-course postoperative coverage. Office debridement is performed as needed based on crusting burden and endoscopic findings, avoiding direct manipulation over the reconstruction. In irradiated cavities, stable epithelialization is typically expected over several weeks and may be delayed compared with nonirradiated patients. This study was conducted in accordance with institutional guidelines. Given that this manuscript describes a surgical technique and a single illustrative case with no patient-identifying information, formal Institutional Review Board approval was not required according to the policies of our institution. The described technique was performed in a 68-year-old man with stage IV left maxillary sinus squamous cell carcinoma that had previously undergone definitive chemoradiotherapy. Nasal endoscopy and computed tomography demonstrated extensive osteoradionecrosis of the posterior maxillary wall and adjacent skull base, with a large bony defect and direct exposure of the middle cranial fossa (Figure 2). Prior imaging reports indicated tumor involvement of the ipsilateral pterygopalatine and infratemporal fossae, making an ipsilateral nasoseptal flap oncologically unsafe. Preoperative contrast-enhanced CT confirmed patency of the contralateral sphenopalatine artery without radiation-induced stenosis. Dedicated CT angiography was not performed. Intraoperatively, brisk arterial bleeding confirmed adequate pedicle perfusion before flap elevation. After multidisciplinary skull base discussion, a contralateral nasoseptal flap with reverse-rotation septal donor-site reconstruction was performed. At 6 months, endoscopy showed complete flap epithelialization without granulation, stenosis, or significant crusting (Figure 1D). Mild donor-site crusting resolved with saline irrigations alone. No office-based debridement or topical therapies were required. Clinical follow-up extended to 12 months postoperatively, with no delayed cerebrospinal fluid leak, sinonasal infection, or revision reconstructive procedure reported. Contralateral nasoseptal flaps offer a valuable salvage option for reconstruction of middle cranial fossa defects when the ipsilateral pedicle is unavailable or unsafe, particularly in the setting of osteoradionecrosis after oncologic treatment. Wide posterior septectomy, careful drilling of the sphenoid rostrum, and meticulous donor-site management with a reverse-rotation septal flap are key technical steps that enhance reach and may reduce donor-site morbidity [4]. The technique described here provides a reproducible approach for experienced endoscopic skull base surgeons facing complex irradiated defects. The reverse-rotation septal flap may reduce donor-site crusting and shorten healing time, and favorable early re-epithelialization rates have been reported in a dedicated case series [5]. However, comparative studies against secondary-intention healing are lacking, and further evidence is needed to confirm a definitive advantage. In irradiated patients, contralateral pedicle viability should be assessed preoperatively. Standard contrast-enhanced CT is generally sufficient; CT angiography or Doppler assessment may be warranted when radiation fields cross the midline. Several technical modifications may be considered based on defect location, mucosal reserve, and anticipated crusting burden. Extending the nasoseptal flap incision inferiorly along the nasal floor can increase surface area and may reduce posterior cavity crusting in selected patients, potentially decreasing reliance on a separate donor-site rotation flap when septal exposure is limited. Conversely, when extensive septal cartilage exposure is anticipated, reverse-rotation mucosal coverage remains valuable to accelerate remucosalization and reduce prolonged postoperative debridement requirements, particularly after radiation. Beyond osteoradionecrosis, this contralateral approach may be useful when the ipsilateral pedicle is unavailable due to prior nasoseptal flap harvest, prior sphenopalatine artery ligation, septal surgery compromising ipsilateral vascular supply, tumor proximity to the pterygopalatine or infratemporal fossae, or when ipsilateral dissection is intentionally avoided for oncologic safety. Contraindications include compromised contralateral septal mucosa, concern for contralateral sphenopalatine system injury, or septal perforation that limits reliable flap elevation. Should the contralateral nasoseptal flap fail, alternatives include a pericranial flap, temporoparietal fascia flap, or free tissue transfer (radial forearm, anterolateral thigh). Contingency options were discussed preoperatively with the multidisciplinary team. The authors have nothing to report. The authors declare no conflicts of interest. The data that support the findings of this study are not openly available because they contain information that could compromise patient privacy. Data are available from the corresponding author upon reasonable request. Video S1: lio270384-sup-0001-VideoS1.mp4. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.