Excision of Tumors of the Prestyloid Parapharyngeal Space

Tumors of the prestyloid parapharyngeal space are uncommon but challenging due to the variety of lesions encountered and the complex anatomy of the involved area. Fortunately, these tumors are generally benign, and therefore, they bring expectations from the patient and the physician that excision should lead to low morbidity and very low mortality. Since patients rarely die of these tumors, the goal of management should be to perform the operation safely with complete removal of the tumors to minimize the risk of recurrence and to preserve surrounding structures. The prestyloid portion of the parapharyngeal space is actually a potential space. It contains adipose tissue, a portion of the deep lobe of the parotid gland (the retromandibular portion), minor salivary glands, and scattered vessels and nerves (Table 29.1). Tumors of salivary gland origin in the pharyngeal space have the same distribution as those in the parotid gland, that is, 80% to 90% are benign and 10% to 20% are malignant. The majority are pleomorphic adenomas. The challenge to the surgeon is understanding tumor behavior and appropriate preparation to manage the simple and complex tumors that are encountered in this area. It is essential that the surgeon is familiar with the anatomy. The prestyloid space superiorly is contained by fascial areas that direct tumor growth. The parapharyngeal space itself is divided into the preand poststyloid areas by the fascia of the styloid process that connects to the tensor veli palatini muscles and its surrounding fascia (Fig. 29.1). Another important structure is the stylomandibular ligament that forms part of the boundary of the stylomandibular tunnel. The stylomandibular ligament unites the fascia of the styloid process to the angle of the mandible. It can be thinned by tumors but is always present, and its division insures adequate opening of the parapharyngeal space and successful subsequent tumor removal. It is also a structure where constriction can occur as tumors grow between the mandible and this ligament. This leads to the classic “dumbbell” tumors that extend from the tail of the parotid gland into the parapharyngeal space. Table 29.2 lists the anatomic boundaries of the prestyloid space.