Surgery of the Soft Palate

Introduction

The soft palate is a subsite of the oropharynx. Its axial plane defines the superior boundary of the oropharynx, incompletely separating it from the nasopharynx above. The soft palate comprises approximately one-third of the palate, with the more anteriorly positioned hard palate making up the remainder; the junction between the hard and soft palates also separates the oral cavity from the more posteriorly located oropharynx. In contrast to the hard palate, the soft palate is a mobile structure that is suspended from the posterior aspect of the hard palate via the palatine aponeurosis. This aponeurosis is formed by the expanded tendon of the tensor veli palatini. The thicker, anterior portion of this tendon constitutes the majority of the anterior soft palate, whereas the posterior aspect of the soft palate is mainly comprised of muscle (levator veli palatine, tensor veli palatini, palatoglossus, palatopharyngeus). At its most posteroinferior extent, the free margin of the soft palate contains a conical muscular projection, the uvula. Functionally, the soft palate is a dynamic structure that is critical for velopharyngeal competence. Elevation of the soft palate puts it into contact with the posterior pharyngeal wall, sealing it off from the nasopharynx (e.g., when swallowing), and its depression puts it in contact with the tongue base, sealing the oral cavity from the nasal passage (e.g., when breathing exclusively through the nose). In this way, function of the soft palate is critical to velopharyngeal competence.

Neoplasms of the soft palate may arise from any of the individual, constituent parts of the soft palate (muscle, lymphatics, mucosa, connective tissue), encompassing a broad variety of benign and malignant tumors ( Table 37.1 ). Importantly, benign tumors of the soft palate are extremely rare, and any soft palate lesion should be considered malignant until proven otherwise. Squamous cell carcinoma is the most common neoplasm of the soft palate, and the oropharynx in general, accounting for more than 90% of all malignant tumors in the oropharynx ( Fig. 37.1 ). Etiologic factors contributing to squamous cell carcinoma are alcohol and tobacco. Although the human papillomavirus (HPV) has more recently been established as an etiologic and positive prognostic factor for oropharyngeal squamous cell carcinoma, a recent review has suggested that significantly less soft palate squamous cell carcinomas are HPV positive than other subsites (22% vs. 70%).

A tumor of salivary gland origin represents the next most commonly encountered tumor of the soft palate, originating in the many minor salivary glands distributed throughout the soft palate. Although the most common benign salivary gland tumor of the soft palate is pleomorphic adenoma, it is estimated that nearly 50% of minor salivary gland tumors in the oropharynx are malignant. The most common of these malignancies are adenoid cystic carcinoma and mucoepidermoid carcinoma. In contrast to the mucosal disruption caused by typical squamous cell carcinomas, minor salivary gland tumors are frequently submucosal.

Lymphatic drainage of the soft palate is primarily to the superior jugulodigastric chain (level II) with subsequent drainage inferiorly to levels III and IV. Importantly the retropharyngeal lymph nodes also receive significant drainage from the soft palate, with one study demonstrating retropharyngeal node involvement of carcinoma in 56% of cancers of the soft palate. Cancers of the soft palate also have a high incidence of metastases to the cervical lymph nodes, with one study demonstrating that 48% of patients with cancer of the soft palate present with metastases to the neck and another 40% who initially presented with an N0 neck who eventually went on to develop cervical lymph node metastases. Because of this, all patients with clinically negative necks still require treatment with either an elective neck dissection or radiation, with bilateral neck dissection required for lesions involving or approaching the midline.

Key Operative Learning Points

• 1.

  The soft palate is a dynamic structure whose function is critical for velopharyngeal competence.

• 2.

  There is a high incidence of cervical lymph node metastasis associated with cancer of the soft palate (particularly with squamous cell carcinoma). Treatment of both necks is recommended for squamous cell cancers involving or approaching the midline.

• 3.

  Reconstruction of the soft palate is complex, and reconstitution of a functional velopharyngeal sphincter is key.

Preoperative Period

Operative Period