Use of Transoral Robotic Surgery for Resection of Parapharyngeal Space Lesions: A Case Series

Background: The parapharyngeal space presents a challenge to head and neck surgeons due to its’ anatomical complexity and low direct visualization. Historically, surgeons relied on imaging studies to predict location, size, and properties of the tumor and surrounding architecture when performing tumor resection. However, with the development of minimally invasive robotic surgery systems, Transoral Robotic Surgery (TORS) has become an increasingly popular choice of technique for head and neck surgeons. TORS provides surgeons better visualization and direct access to surgical sites, allowing for tumor excision via endoscope without having to perform extensive incisions. Pleomorphic adenomas are the most common primary lesions in the parapharyngeal space. As these adenomas tend to have soft interiors, they are prone to be friable with a high risk of rupture and spillage during tumor resection. Given these characteristics, it is necessary to determine whether TORS is a viable and efficient strategy for resection of masses in the parapharyngeal space.

Objective: To determine feasibility of transoral robotic surgery for resection of parapharyngeal space lesions.

Methods: Retrospective case series. Patients who received TORS for parapharyngeal space lesions between 2015 and 2016 were reviewed. Two male and two female patients, for a total of 4 cases, were included in this study. Of these cases, one patient was diagnosed with a benign epithelial cyst and three were diagnosed with pleomorphic adenomas.

Results: In the three cases of pleomorphic adenoma, the tumor capsules were first incised and resection was completed via debulking of the tumor core followed by capsule excision. During resection of the benign epithelial cyst, the capsule ruptured and fluid was drained from the cyst prior to resection. Copious wash-out of the surgical cavity was performed post-resection for all cases. Tumor size ranged from 1.5 × 1 × 2 cm to 6 × 4 × 6.5 cm, and surgical procedures lasted from 2 hours and 5 minutes to 3 hours and 25 minutes with minimal blood loss (between 10 and 150 mL). There were no intra-operative or postoperative complications, and all patients were discharged in 1 or 2 days postsurgery. Median follow-up was 11 months (ranging from 3 to 16 months). All patients reported normal swallowing function and presented with no infection at the surgical site. Images at the 3 months’ (two cases) or 12 months' (two cases) mark did not show any recurrence of disease.

Conclusions: A review of the four cases revealed transoral robotic surgery to be a safe and feasible option for removing masses in the parapharyngeal space. The lesion’s capsule was either intentionally incised, to allow for debulking of tumor, or unintentionally ruptured, as in the case of the cyst. Complete resection was achieved in all cases. Despite short follow-up in our series, no evidence of recurrence was present at the 3-month (two cases) or 12-month (two cases) follow-up. Despite concerns on tumor spillage due to the friable nature of these lesions, pathology reported negative surgical margins for all four surgeries.