Surgical Outcome of Extracapsular Dissection of Benign Parotid Gland Tumor: A Comparative Study to Superficial Parotidectomy

Background/Objectives: Extracapsular dissection has the advantage of reducing complications by minimizing tissue loss of the parotid without intentionally exposing the facial nerve in patients with benign parotid tumor. However, there has been controversy over the surgical results. Thus, the surgical outcomes of extracapsular dissection for benign parotid tumor was compared to those of superficial parotidectomy.Materials & Methods: A retrospective chart review was conducted with 132 patients who received surgery for benign parotid tumor in our center from January 2014 to December 2018 retrospectively.Results: A total of 132 people were enrolled, with 62 people receiving extracapsular dissection, 38 people receiving partial superficial parotidectomy and 32 people receiving superficial parotidectomy. No significant difference was found between the three groups regarding complications such as facial nerve palsy, Frey's syndrome, or first bite syndrome. Operation time and hospital stay was significantly short in extracapsular dissection group.Conclusion: For well-selected cases, extracapsular dissection can be considered as an option for surgery of benign parotid tumor.

Three-Dimensional Sheath Inked Rapid Acquisition with Refocused Echoes Imaging (SHINKEI) MRI for Delineating the Intraparotid Facial Nerve Branches and Their Anatomical Relationship with Parotid Tumors

Background: Accurate imaging of the anatomical relationship between the intraparotid facial nerve branches and parotid tumor can be helpful for surgical planning and effective protection of the facial nerve during surgery. Three-dimensional sheath inked rapid acquisition with refocused echoes imaging (3D-SHINKEI) is a new MRI sequence with a high tissue contrast resolution, which has been used for imaging the peripheral nerves in several organs. Objectives: To evaluate the value of 3D-SHINKEI sequence in representing the intraparotid facial nerve branches and their anatomical relationship with neoplasms of the parotid gland. Patients and Methods: Thirty-six patients with parotid tumors underwent MRI with 3D-SHINKEI and 3D-T2-fast field echo (3D-T2-FFE) sequences in the coronal plane. The contrast-to-noise ratios (CNRs) and signal intensity ratios (SIRs) of the facial nerves in the two sequences were compared. The relationship between the intraparotid facial nerve branches and parotid tumor was also analyzed in 36 patients, and the results were compared with the intraoperative anatomy and postoperative pathological findings. Results: The image quality score of the 3D-SHINKEI sequence for anatomical representation of the intraparotid facial nerve branches was significantly higher than that of the 3D-T2-FFE sequence (Z = −6.197, P < 0.01). The SIRs and CNRs of the facial nerves were significantly higher in the SHINKEI images as compared to the 3D-T2-FFE images (t = 10.772, P < 0.01 and t = 11.586, P < 0.01, respectively). The delineation accuracy of the anatomy of the main trunk of the facial nerve and its first-level branches and their relationship with tumors was significantly higher with the 3D-SHINKEI sequence than with the 3D-T2-FFE sequence (P < 0.01). Besides, the relationship between parotid tumors and the main trunk of the facial nerve and its first-level branches was classified into six types. Conclusion: A high-resolution 3D-SHINKEI sequence could accurately represent the relationship between the intraparotid facial nerve branches and parotid gland neoplasms. It was also found to be more accurate than the 3D-T2-FFE sequence.

Differential Expression of Peroxisomal Proteins in Distinct Types of Parotid Gland Tumors

Salivary gland cancers are rare but aggressive tumors that have poor prognosis and lack effective cure. Of those, parotid tumors constitute the majority. Functioning as metabolic machinery contributing to cellular redox balance, peroxisomes have emerged as crucial players in tumorigenesis. Studies on murine and human cells have examined the role of peroxisomes in carcinogenesis with conflicting results. These studies either examined the consequences of altered peroxisomal proliferators or compared their expression in healthy and neoplastic tissues. None, however, examined such differences exclusively in human parotid tissue or extended comparison to peroxisomal proteins and their associated gene expressions. Therefore, we examined differences in peroxisomal dynamics in parotid tumors of different morphologies. Using immunofluorescence and quantitative PCR, we compared the expression levels of key peroxisomal enzymes and proliferators in healthy and neoplastic parotid tissue samples. Three parotid tumor subtypes were examined: pleomorphic adenoma, mucoepidermoid carcinoma and acinic cell carcinoma. We observed higher expression of peroxisomal matrix proteins in neoplastic samples with exceptional down regulation of certain enzymes; however, the degree of expression varied between tumor subtypes. Our findings confirm previous experimental results on other organ tissues and suggest peroxisomes as possible therapeutic targets or markers in all or certain subtypes of parotid neoplasms.

Augmented Reality with HoloLens® in Parotid Tumor Surgery: A Prospective Feasibility Study

<b><i>Introduction:</i></b> Augmented reality can improve planning and execution of surgical procedures. Head-mounted devices such as the HoloLens® (Microsoft, Redmond, WA, USA) are particularly suitable to achieve these aims because they are controlled by hand gestures and enable contactless handling in a sterile environment. <b><i>Objectives:</i></b> So far, these systems have not yet found their way into the operating room for surgery of the parotid gland. This study explored the feasibility and accuracy of augmented reality-assisted parotid surgery. <b><i>Methods:</i></b> 2D MRI holographic images were created, and 3D holograms were reconstructed from MRI DICOM files and made visible via the HoloLens. 2D MRI slices were scrolled through, 3D images were rotated, and 3D structures were shown and hidden only using hand gestures. The 3D model and the patient were aligned manually. <b><i>Results:</i></b> The use of augmented reality with the HoloLens in parotic surgery was feasible. Gestures were recognized correctly. Mean accuracy of superimposition of the holographic model and patient’s anatomy was 1.3 cm. Highly significant differences were seen in position error of registration between central and peripheral structures (<i>p</i> = 0.0059), with a least deviation of 10.9 mm (centrally) and highest deviation for the peripheral parts (19.6-mm deviation). <b><i>Conclusion:</i></b> This pilot study offers a first proof of concept of the clinical feasibility of the HoloLens for parotid tumor surgery. Workflow is not affected, but additional information is provided. The surgical performance could become safer through the navigation-like application of reality-fused 3D holograms, and it improves ergonomics without compromising sterility. Superimposition of the 3D holograms with the surgical field was possible, but further invention is necessary to improve the accuracy.