How To: Tunneled Submental Island Flap for Reconstruction of Endoscopic Nasopharyngectomy Defects

INTRODUCTION

Salvage nasopharyngectomy for recurrent nasopharyngeal carcinoma (NPC) is a morbid procedure. Sequelae may include velopharyngeal insufficiency (VPI), skull base osteomyelitis, and internal carotid artery (ICA) blowout syndrome, which carries a 60% risk of mortality. Robust reconstruction of the surgical defect is imperative, especially if re-irradiation of the field is to be considered. Nasoseptal flaps (NSFs) are the workhorses for the reconstruction of skull base defects; however, they present several drawbacks for the reconstruction of nasopharyngeal defects. The NSF is thin, and the tissue from which it is harvested may have withstood radiation for the primary treatment of NPC.

The ideal reconstruction would offer healthy vascularized tissue with adequate bulk to limit VPI and provide protection to the cervical ICA. The submental artery island flap (SMIF) offers a sizeable musculocutaneous flap with a reliable vascular pedicle, preventing the need for microvascular anastomosis. Additionally, the flap lies largely outside of typical radiation fields used for NPC, as the lymphatic drainage of the nasopharynx essentially bypasses the Level 1 nodal station.

The SMIF is commonly used for the reconstruction of skin and mucosal defects. Dissection of the vascular pedicle to the artery and vein of origin allows reliable reach for lateral skull base defects. Similarly, this long, narrow pedicle allows the flap to reach the nasopharynx and central skull base when directed along a more medial vector through the parapharyngeal space. This study details the utilization of a pedicled SMIF for reconstruction after endoscopic nasopharyngectomy in a patient with recurrent NPC.

METHODS

A 58-year-old male presented with recurrent (rycT2N0M0) NPC two years after the completion of definitive chemoradiotherapy (CRT) for his initial disease. MRI demonstrated recurrent tumor involving the right fossa of Rosenmüller, Eustachian tube, and parapharyngeal space with 180-degree contact of the parapharyngeal ICA (Fig. 1). There was no obvious perineural spread, intracranial extension, or extension to the prevertebral fascia. The patient underwent an expanded endoscopic endonasal approach (EEA) for salvage nasopharyngectomy. Reconstruction of the nasopharyngeal defect was accomplished with a pedicled SMIF to provide appropriate tissue bulk in the infratemporal fossa (ITF) and guard the ICA. Approval from the Institutional Review Board (IRB) was requested, and this project was determined to be

IRB-exempt.

RESULTS

A Denker’s extended medial maxillectomy was performed on the right, along with a complete ethmoidectomy and posterior septectomy to create a common sphenoid cavity. A left NSF was harvested and tucked into the ipsilateral maxillary sinus. The contents of the pterygopalatine fossa (PPF) were mobilized inferolaterally, and the greater sphenoid wing (GSW) and pterygoid plates were drilled to expose the ITF. The lateral pterygoid muscle (LPM) was elevated from the GSW and resected, exposing the foramen ovale and foramen spinosum. The parapharyngeal ICA was identified, and the tumor was dissected off the vessel. Tumor dissection continued medially along the prevertebral fascia. A right neck dissection was performed for vascular control and nodal sampling.