Introduction:
Parapharyngeal tumors are the group of tumors that most often tend to pose a clinical challenge to surgeons, especially for planning surgical interventions. These tumors occur within the potential space that is lateral to the upper pharynx and are relatively uncommon, yet unique and surgically challenging tumors of the head and neck. Even though they contribute to around one percent of the major neoplasms of the head and neck, there is a possibility that they can be either benign (noncancerous) or malignant (cancerous). While the incidence of benign tumors of the para pharyngeal space is about 70 to 80 percent, 20 to 30 percent of these tumors are cancerous or malignant.
What Are the Surgical Procedures for Resecting These Tumors and Their Goals?
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The most common procedures that are adopted by maxillofacial surgeons for accessing the skull base lesions or para pharyngeal tumors are the maxillofacial access osteotomies. The maxillofacial access osteotomy procedures give scope for not only excellent visualization but also permit the operator to surgically manipulate and reposition the field of work. Access to osteotomy during these procedures further allows the surgeon adequate access to the surgical field. This allows for effective resection of the skull base tumor completely. The clinical challenge encountered by oral surgeons during the procedure of eliminating PPS (parapharyngeal space) tumors is the accessibility to the skull base lesions. Hence, it is a known fact to oral surgeons that the success of surgery lies certainly in choosing or selecting the right approach to the skull base lesions.
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In comparison to most other facial osteotomies that have been traditional, the current-day osteotomy approach involves the paramedian mandibular swing approach. This is used typically before a maxillary osteotomy or a lip split incision technique with a mandibulotomy technique. In the case of surgeries involving the lower jaw, mandibulotomy is commonly preferred to eliminate these cancers. The surgeon ensures that there is an approach to the part of the oral cavity, and the oropharynx region with minimal patient morbidity. This combination of swing approach with mandibulotomy surgery is in fact touted to be a modern-day significant approach that has its own advantages over most other facial osteotomies. This is because this "swing" approach can give easy access for the surgeon to the neck and skull base together (that is otherwise a surgical challenge that is encountered in any other oro facial osteotomy).
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The aim of the surgeon is to not just reestablish the functions post-surgery in head and neck regions, but also to provide the cosmesis and psychosocial motivation needed for the patients to lead a normal life again.
What Are the Steps in the Surgical Resection or Elimination of PPS Tumors?
The para pharyngeal space is a complex anatomic space with the surgeons having difficulty accessing them i.e. the skull base tumors or lesions for any surgical interventions. This is particularly true because of the difficulty in complete resection of the PPS cancer or tumor. The steps in the surgical resection of PPS tumors are as follows:
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The patients are administered general anesthesia and made to lie down in a supine position.
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In the swing approach, the head is turned to the left side, and the neck is usually extended with the help of a sandbag after sterile draping that can be easily placed under the patient's right shoulder. The swing procedure be it for maxillary or mandibular osteotomy surgeries ensures that even highly vascular cancers can be respected or excised by the surgeon with minimal blood loss and with minimal post-operative complications.
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The procedure usually requires an interdisciplinary team approach both from the maxillofacial and oncologist members of the team.
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A curvilinear incision is indicated for skull base lesions that extend usually from the right mastoid region, to the chin, and further alongside the skin of the neck.
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Skin flaps are then raised to the lower border of the mandible at the level of the subplatysma.
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Lip split incision is most commonly made with an elevation of the periosteum from the lower jaw or the mandible. The lip-split mandibulotomy (LSMA) is in fact the most common access procedure that has been used in head and neck (H&N) surgeries for cancer elimination. These procedures also aid surgical resection of those inaccessible tumors, especially in the posterior oral cavity and in the oropharynx.
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After the tumors are accessed and the mandibulotomy performed, with care taken by the oral and maxillofacial surgeon as well as the oncologist to avoid both dental and physical damage to the vital orofacial structures, the mandible is swung around in a lateral and superior direction.
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Care is further ensured by the surgeons to elevate the lingual tissues in order to favor the reattachment of tissues again.
What Precautions Should Be Taken by the Surgeons Pre and Post-surgery?
The points that are considered while performing the PPS tumor elimination are the following:
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The surgeon visualizes the proximity of the lesions to the inaccessible pharyngeal walls.
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The size of the tumor should be noted if the tumors have malignant potential. Wider access is required to gain clearance.
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The vascularity of the tumor should be assessed thoroughly and preoperatively by the oral surgeon and the oncologist.
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The tumor's proximity to the neurovascular structures around it should be observed.
Conclusion:
The surgical management of parapharyngeal space tumors is only challenging because of the way of approach that can cause complications to vital structures surrounding the skull base, but further, it requires interdisciplinary team management from the oral and maxillofacial surgeon, oncologist, and the neuro/head and neck surgeons as well. The aim of eliminating these complex tumors should always include the preservation of vital structures, in the head and neck regions. Despite modern-day advances in maxillofacial surgery instruments and methods and also even though numerous surgical techniques exist, it is important to not underestimate the clinical challenges in eliminating parapharyngeal tumors completely. Hence the selection of the proper surgical technique must be a key determinant or factor that establishes the long-term outcomes in patients afflicted by these skull base lesions or PPS tumors.
