Parotid Tumour Surgery: Revisiting the Past and Getting Inspired for the Future

Parotid tumour surgery consists an important chapter of Oral and Maxillofacial Surgery, being a continuous challenge for the surgeon of the area, mainly due to two reasons: 1) the close and intimate anatomic relationship of the parotid gland and the facial nerve (VII cranial nerve), & 2) the postulated higher recurrence rate of pleomorphic adenoma, which is the most common parotid tumour, after its incomplete removal , due to rupture of its capsule and dissemination of the tumour in the glandular parenchyma. There is an assumption that pleomorphic adenomas can have pseudopodia, and that their capsules can be thin or incomplete. Salivary gland neoplasms account for only 3-6% of head and neck tumours, 75-85 % of them are parotid tumours, and 70-80% of the parotid tumours are benign. Pleomorphic adenoma or mixed tumour represents the most common subtype of benign parotid tumours. Adenocarcinoma, adenocystic carcinoma, mucoepidermoid carcinoma, and acinic cell carcinoma are the most common malignant parotid tumours. Various surgeons occupied with parotid tumour surgery, starting in 1793 when Adam Elias von Siebold attempted to remove surgically a parotid tumour for the first time. Among them leading figures of Surgery are included, such as Christian Albert Theodor Billroth, Nicholas Senn, Walter Ellis Sistrunk, and Robert M. Janes to name a few. The surgical techniques applied mainly for the removal of benign parotid tumours, gradually developed from enucleation to extracapsular dissection, and from superficial parotidectomy to partial superficial parotidectomy, after identification and dissection of the facial nerve in both cases. In the 1^st International Accord on modern management of salivary gland disease, which was held in Paris, France, on July 4-5, 2008, a new approach towards surgery of benign parotid tumours was recommended, rather individual and non-standardized, thus offering the possibility to apply less radical techniques like partial parotidectomy and extracapsullar dissection beside the classical lateral and total parotidectomy.

Surgical techniques applied today for removal of pleomorphic adenoma and benign parotid tumours in general, are the following: i) partial superficial parotidectomy after identification and dissection of the facial nerve, especially of those branches that are adjacent to the tumour site, ii) superficial parotidectomy after identification and dissection of the facial nerve, iii) extracapsular dissection of the tumour, especially in cases of benign tumours which are located peripherally of the gland, they are mobile, and their diameter is ≤ 2.5 cm, iv) compulsory enucleation of the tumour, especially in cases where the relationship of the facial nerve and the tumour is such, that the facial nerve “embraces” the superficial or the deep surface of the tumour’s capsule, pushed by the tumour outwards or inwards respectively, and v) total parotidectomy after identification, dissection, and preservation of the facial nerve, mainly in cases of benign tumours located in the deep lobe, as well as in cases of recurrent pleomorphic adenoma.

On the other hand, surgical techniques applied today for removal of malignant parotid tumours include i) partial superficial parotidectomy, where the tumour is removed with at least 5 mm tumour free margins, ii) superficial parotidectomy, where the entire superficial lobe of the gland is removed, after identification, dissection, and preservation of the facial nerve, iii) conservative total parotidectomy or total parotidectomy, where the superficial and the deep lobe of the gland are removed, after identification, dissection, and preservation of the VII nerve, iv) radical total parotidectomy, where the superficial and the deep lobe of the gland are removed with sacrifice of the VII nerve, in cases of direct engagement of the facial nerve during parotidectomy, and v) extended parotidectomy, where the superficial and the deep lobe of the gland are removed with sacrifice of the facial nerve, as well as of adjacent infiltrated structures (mandible, infratemporal fossa, skull base, parapharyngeal space). It should be pointed out that the indications for neck dissection in parotid gland cancer are not sufficiently defined so far. Last but not least, continuous intraoperative facial nerve monitoring in parotid surgery, better enables the surgeon to more “gently” dissect and protect the facial nerve. Its use is advocated in general, in spite the fact that the existing limited randomized studies show that, the incidences of immediate and late facial nerve dysfunction were similar between patients with benign parotid tumors subjected to superficial parotidectomy, with or without continuous intraoperative electromyographic neuromonitoring. However, immediate facial nerve dysfunction was more severe among the non-monitored patients.