How to: Nasoseptal Flap to Repair Large Maxillary Sinus Floor Defects

INTRODUCTION

An oroantral fistula (OAF) is an epithelialized tract from the maxillary sinus to the oral cavity. OAFs occur most commonly after maxillary molar extraction, but may also occur following tumor resection or osteoradionecrosis. For OAFs after dental extraction, multiple studies have demonstrated OAF closure success rates of 90% or greater with transoral approaches such as buccal mucosal or fat pad advancement flaps (Eur J Oral Implantol. 2014;7:347–357). However, when OAF closures fail, salvage transoral reconstructive options may be limited.

In recent years, lateral nasal wall (Laryngoscope. 2022;132:2259–2261), greater palatine artery (Laryngoscope. 2022 [published online ahead of print]), and nasoseptal flaps (NSFs) (J Oral Maxillofac Surg. 2016;74(704):e701–e706) have been used to close OAFs after dental extractions. Noel et al. published the only report of a successful NSF reconstruction of a 2 x 1.5 cm2 OAF after dental extraction and previous chemoradiation (J Oral Maxillofac Surg. 2016;74(704):e701–e706). Based on literature to date, if buccal or palatal mucosa or buccal fat is available for OAF repair, high success rates should be expected, and transnasal options should be unnecessary. However, should transoral options be limited or unavailable, recent reports have demonstrated success in closing OAFs with different intranasal mucosal flaps.

This article describes using an NSF to close a large maxillary sinus floor defect if transoral options are limited or unavailable to the otolaryngologist, with emphasis on technical nuances to assist surgeons in performing this technique.

METHOD

A 74-year-old male suffered from a recurrent deep neck space abscess after infrastructural maxillectomy and adjuvant radiation therapy for a buccal and alveolar ridge squamous cell carcinoma. His radial forearm free flap skin paddle that had been used previously to reconstruct the sinus floor dehisced, causing a fistula between the sinus and neck.

Due to a lack of transoral reconstructive options, a transnasal repair was planned. He had an intact nasal septum and nasal floor, and given the size of the sinus floor defect and previously radiated tissue bed, a large vascularized nasoseptal flap was felt to offer the highest likelihood of success.

Cadaver Dissection

To prepare for the case, a cadaveric dissection was performed to simulate the transnasal closure of a complete maxillary sinus floor defect. An NSF was first harvested by making an incision along the choanal rim and vomer, and across the nasal floor along the soft/hard palate junction to the lateral wall of the inferior meatus. The incision was then carried anteriorly to the pyriform aperture, staying inferior to the nasolacrimal duct orifice.

The superior flap incision began at the sphenoid ostium, then was carried along the septum about 1 cm below the cribriform plate, and anteriorly to the septal mucocutaneous junction, then connected to the lateral incision along the pyriform aperture. Note that the superior and inferior posterior choanal rim incisions were carried far laterally to the region of the sphenopalatine foramen to improve pedicle mobility. The flap was elevated in submucoperichondrial/osteal planes, then tucked into the nasopharynx until the reconstruction.

Next, to facilitate flap advancement into the maxillary sinus, a modified endoscopic Denker’s approach was performed by removing the inferior turbinate and medial maxillary sinus wall, preserving the bone at the pyriform aperture, and transecting the nasolacrimal duct. The NSF was then rotated into the maxillary sinus to cover the entire sinus floor (Figure 1). This was then carried out on the patient.

Surgical Case

Intraoperatively, the NSF was harvested and the modified endoscopic Denker’s approach was performed as in the cadaver dissection, the maxillary sinus walls were prepared for NSF inset. The previous free flap appeared viable and occupied the anterior third of the sinus floor, but had pulled away posteriorly, angling inferiorly away from the anterior maxillary sinus wall as it fistulized into the neck.

To optimize wound healing potential, a maximal amount of contact was desired between the NSF, maxillary sinus walls, and free flap. A suction monopolar Bovie was used to cauterize and incise mucosa around the sinus floor defect. Angled curettes and grasping forceps were then used to remove 5–10 mm of mucosa from the anterior, lateral, and posterior maxillary sinus walls around the perimeter of the sinus floor defect.

When the NSF was first rotated into the maxillary sinus through the medial maxillectomy opening, it barely covered the posterior third of the floor defect and appeared to be at high risk for failure. Pedicle rotation was inhibited by portions of the palatine bone and posterior maxillary sinus wall, as well as the inferior and middle turbinate stumps.

Carefully removing the turbinate stumps and bone in this region significantly enhanced pedicle mobility. The NSF was then advanced to cover the entirety of the maxillary sinus floor without tension. Adherus dural sealant was then placed over all flap edges. No additional intranasal packing was placed.

RESULTS

The patient’s neck fistula closed, the abscess resolved, and he had no long-term sinonasal mucopurulence, crusting, or epiphora. He had premorbid left upper lip and cheek hypesthesia after his prior maxillectomy, but no new hypesthesia.

In conclusion, NSFs can be used to repair large maxillary sinus floor defects when transoral options are infeasible. Future studies will be beneficial in determining which intranasal flaps are optimal for closing OAFs of different sizes and locations.