Transoral Approach to the Parapharyngeal Space

Introduction

The management of patients with tumors of the parapharyngeal space (PPS) is a challenge for head and neck surgeons. The diverse anatomic structures in the PPS give rise to many different tumors, and the relationship of such lesions to critical neurovascular contents provides a technical challenge during surgery. Various operative techniques have been described to safely approach this deep neck space. However, while considering that 80% of PPS tumors are benign, the correct approach to minimize surgical morbidity while successfully treating the patient should be chosen. Of the many approaches to the PPS, the transoral approach has been an ideal technique for carefully selected tumors and minimizes complications experienced with other surgical alternatives.

Key Operative Learning Points

The transoral approach to the PPS should be reserved for benign prestyloid tumors.
Fine-needle aspiration should be performed preoperatively to rule out malignancy.
Cross-sectional imaging should identify that the carotid artery is displaced posterolaterally.
The transoral robotic approach can provide improvement in optics of the surgical procedure and allow for a surgical assistant at the bedside to facilitate dissection.
Blunt dissection, meticulous hemostasis, and careful attention to closure of the pharyngeal incision are critical in avoiding complications.

Preoperative Period

History

Most patients are asymptomatic, with tumors incidentally found during unrelated imaging.
When symptomatic, patients commonly present with awareness of an intraoral mass or a mass in the neck.
Facial pain or cranial neuropathies are usually associated with malignant lesions, which are not amenable to transoral removal.

Physical Examination

Oral cavity/oropharyngeal exam ination: The most common finding is a mass displacing the tonsil/soft palate or both, medially. In addition, the mouth opening should be adequate for transoral surgical exposure.
Examination of the neck may demonstrate a palpable mass. However, only 28% of patients present with both an intraoral and external neck mass.
Additional findings may include paralysis of the vocal cord and/or palate, middle ear fluid on the side of the lesion, Horner’s syndrome, and pulsations over the mass in the neck.

Imaging

Cross-sectional imaging with contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) is used to determine the relationship of neoplasms to vasculature structures. In addition, imaging provides information on the location of the tumor in the prestyloid versus poststyloid space.
Imaging can provide information on the vascularity of the mass.
Transoral fine-needle aspiration (FNA) of palpable and visible lesions is usually well tolerated by patients in the office setting. However, inadequate stabilization of PPS masses as well as limits of intraoral angles may require a CT-guided FNA through the skin, rather than making a “blind” pass toward a mass with large caliber vasculature structures adjacent to the lesion.

Indications

Benign cysts/neoplasms isolated to the prestyloid PPS
- Salivary gland neoplasms; most commonly pleomorphic adenomas
- Trigeminal nerve branch schwannomas
- Lipomas

Contraindications

Malignant tumors
Poststyloid PPS masses
Patients with significant trismus
Vascular tumors such as paragangliomas due to proximity to the carotid artery
Tumors involving the skull base
Tumors with significant extension to the deep lobe of the parotid or the stylomandibular tunnel

Operative Period

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