Extracapsular dissection versus superficial parotidectomy for benign parotid tumors

BACKGROUND Surgery for benign parotid tumors has undergone several evolutionary steps over the past century. Prior to the 1930s, the focus of parotid surgery was to limit the risk of facial nerve paralysis, which made intracapsular enucleation the most common procedure performed. However, it became widely recognized that the postoperative risk of recurrence was unacceptably high, even for benign disease. Thus, surgeons began advocating for the superficial parotidectomy (SP) and/or partial parotidectomy, which decreased the recurrence rate to its current level of approximately 2%. With the decrease in recurrence also came the unwanted side effects of increased facial nerve injury, Frey’s syndrome, and salivary fistula. Recently, extracapsular dissection (ECD) has emerged as an adjunctive method for removing benign parotid tumors. Extracapsular dissection can be differentiated from intracapsular enucleation, which involves incising the tumor capsule and “shelling out” the neoplasm, thus resulting in high rates of recurrence due to incomplete resection and seeding of the tumor within the parotid bed. Extracapsular dissection is conducted by careful dissection around the tumor capsule under magnification without preidentification of the facial nerve. The use of this technique has demonstrated decreased surgical complications from benign parotid tumor resection for a certain subset of patients. The evidence supporting the use of ECD for benign parotid tumors, which meet certain criteria, will be the focus of this article. LITERATURE REVIEW The larger studies reporting on ECD for benign parotid tumors have primarily come from Europe. In terms of patient selection, most studies advocate for smaller, superficial-lobe, mobile tumors. In the largest series of ECD by McGurk et al., which retrospectively compared 503 patients who underwent ECD to 159 who received a SP, the authors utilized both a 4-cm cutoff for consideration of an ECD as well as intraoperative determination of tumor mobility to decide between the two techniques. In one study by Piekarski et al., the risk of facial paresis after ECD of tumors 4 cm or greater was 21% compared to 4% for those for whom the tumor was less than 4 cm. Although all of the authors agree that ECD should be reserved for those tumors with benign etiology, some indicate that preoperative fine needle aspiration (FNA) is not necessary and others argue that it should be routinely used due to the high sensitivity and specificity. Because most of the studies are conducted in Europe, ultrasound was the imaging modality of choice for two of the groups, with computed tomography and/or magnetic resonance imaging reserved for suspected bony and/or deep lobe involvement, respectively. A consensus is generally reached that the tumors that demonstrate worrisome features intraoperatively should undergo a more extensive surgery than ECD, regardless of the FNA result, due to the 20% false-negative rate for malignancy seen on FNA. This point also highlights the need for the technique to be utilized by experienced parotid surgeons who can identify suspicious characteristics for parotid malignancy as well as perform an appropriate parotid surgery for the particular histology. As mentioned above, ECD is conducted by careful dissection around the tumor capsule under magnification without preidentification of the facial nerve. A loose areolar plane, approximately 2to 3-mm adjacent to the tumor capsule, is the described plane of dissection. Iro et al. advocate for the use of intraoperative facial nerve neuromonitoring and bipolar cautery to prevent injury to the branches of the facial nerve that can sit adjacent to the tumor capsule. Given the pseudopods of tumor that are readily described in pleomorphic adenomas, magnification is encouraged to better visualize these outcroppings and avoid capsular rupture. From the Department of Otolaryngology/Head and Neck Surgery, Louisiana State University Health–Shreveport, Shreveport, Louisiana, U.S.A The authors of this original manuscript have no financial disclosures and no conflict of interest. Editor’s Note: This Manuscript was accepted for publication on September 24, 2014. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Vikas Mehta, MD, Co-Director of Head and Neck Surgical Oncology Feist-Weiller Cancer Center, 1501 Kings Highway, Rm 9-203, Shreveport, LA 71130. E-mail: dr.vikasmehta@gmail.com