Nasopharyngectomy with operating microscope: A case series

Abstract

Background

Nasopharyngectomy for excision of nasopharyngeal tumors is challenging, as access to the nasopharynx is difficult. Recently our institution embarked on two new approaches – robotic nasopharyngectomy and open nasopharyngectomy with operating microscope (NOM) via maxillary swing approach. This article proposes that the novel approach of NOM via maxillary swing aids visualization for resection of locally invasive nasopharyngeal tumors.

Methods

Over a thirteen-month period, eight patients required nasopharyngectomy in our single Asian institution. Four underwent robotic nasopharyngectomy and four underwent NOM via maxillary swing approach. The latter four were retrospectively reviewed, and their clinical characteristics and surgical outcomes reported. Tips and pearls for operative setup and patient selection were also discussed.

Results

All four patients who underwent NOM had negative intraoperative frozen sections with subsequent negative paraffin sections. All patients remained disease free post-salvage surgery.

Conclusion

NOM via maxillary swing allows better visualization and aids in augmentation of open nasopharyngectomy. This enables achievement of adequate resection margins and fewer surgical complications in locally invasive nasopharyngeal tumors.

1 Introduction

1.1 Background

Local recurrence of nasopharyngeal carcinoma (NPC), a disease with geographical predilection to Southern China and Southeast Asia, occurs in 10% of patients . The gold standard of care is salvage nasopharyngectomy via maxillary swing approach , which offers better local tumor control, lower morbidity and improved survival compared to re-irradiation . Nasopharyngectomy is also indicated for other rare head and neck malignancies such as adenoid cystic carcinoma, mucosal melanoma and sarcomas. The relatively inaccessible location of the nasopharynx poses a major challenge of adequate visualization intra-operatively. Achieving clear resection margins and avoidance of vital structures in the vicinity such as the internal carotid artery (ICA) are challenging.

Recently our institution has embarked on two new approaches – robotic nasopharyngectomy and nasopharyngectomy with operating microscope (NOM) via maxillary swing approach. Robotic nasopharyngectomy is generally indicated for smaller tumors , as it offers limited access to the nasopharynx. More invasive tumors that lie more laterally and close to the ICA require greater surgical exposure. In this case series we aim to demonstrate that NOM via the maxillary swing approach aids in better tumor visualization for resection of locally invasive nasopharyngeal tumors. This aids the surgeon in achieving hemostasis, better visualization of tumor margins and critical structures.

2 Methods

Over a thirteen-month period between May 2013 and June 2014, there were eight patients with nasopharyngeal tumors in whom nasopharyngectomy was indicated at the Singapore General Hospital. Four patients underwent robotic nasopharyngectomy and four underwent NOM via maxillary swing approach. Patients chosen for NOM with maxillary swing fulfilled one of the following conditions: tumor close to the ICA (one millimeter or less), tumor in the lateral position, and tumor creeping up the roof of the posterior nasal space (PNS). We retrospectively reviewed the four patients who underwent NOM with maxillary swing.

Pre-operatively, each patient underwent nasopharyngoscope examination, with biopsy taken for histological analysis. A complete clinical exam, positron emission tomography (PET) or computed tomography (CT) scan were done to assess any systemic tumor invasion that would deem the patient to be unsuitable for surgery. Magnetic resonance imaging (MRI) was used to assess extent of disease, ruling out any contraindications for surgery such as skull base erosion and parapharyngeal extension with encasement of the petrosal internal carotid artery. Patients were discussed at a multidisciplinary tumor board meeting, comprising of head and neck surgeons, medical oncologists, radiation oncologists, radiologists and pathologists. The decision for surgery and any adjuvant treatment if indicated was then made. Pre-operative blood tests included full blood count, renal panel and coagulation panel to ensure that the patients were optimized. Any other pre-operative risk factors were optimized as well.

Intra-operatively, the patients then underwent a modified nasopharyngectomy via the maxillary swing approach with use of the operating microscope (Carl Zeiss S88/OPMI Vario®). Surgical instruments used were standard for open surgery. Microsurgical instruments were not necessary.

A Weber–Ferguson–Longmire incision was made with sub-ciliary extension ( Fig. 1 ), and drilling of holes to fix mini plates was done before the osteotomy was performed on the anterior wall of the maxilla, zygomatic arch and hard palate. The maxilla on the ipsilateral side of the tumor was then swung out with overlying skin and subcutaneous tissue attached, exposing the posterior nasal space (PNS) ( Fig. 2 ). The operating microscope was then positioned directly over the exposed PNS ( Fig. 3 ). Nasopharyngectomy was performed with better visualization under direct vision using the operating microscope ( Figs. 4 and 5 ). Radial and deep tumor margins were taken intra-operatively for frozen section, and were ensured to be free of tumor. This was later confirmed by subsequent paraffin sections.