Superficial Parotidectomy




Introduction


Tumor resection is the most common indication for superficial parotidectomy. Approximately 85% of parotid neoplasms are benign. Malignant tumors vary greatly in behavior, from the indolent (acinic cell carcinoma) to the highly lethal (carcinosarcoma). A recent surveillance epidemiology and end results (SEER) data base review of more than 22,000 cases showed that mucoepidermoid carcinoma continues to be the most common salivary gland malignancy (31%). Some high-grade malignancies may be managed with superficial parotidectomy but require neck dissection as well. Metastatic lymphadenopathy from primary skin malignancies is also a common indication for parotidectomy. Lymphoma poses a particular challenge to the parotid surgeon—accurate diagnosis may be available only after open biopsy. Therefore it is important to keep lymphoma in the differential to avoid extirpative surgery for this medically-managed disease. Chronic parotitis is a less common indication for superficial parotidectomy and is recommended for patients who are refractory to medical management or minimally invasive techniques.




Key Operative Learning Points





  • Superficial parotidectomy allows resection of either part or all of the gland lateral to the facial nerve.



  • The facial nerve has arbitrarily been set as the divider of the parotid, actually a single structure, into superficial (lateral) and deep lobes.



  • Systematic dissection—dividing the parotidomasseteric fascia; identifying the “pointer” of the cartilaginous external auditory meatus, mastoid tip, and tympanomastoid suture line; and delicate handling of the tissues to avoid undue bleeding—allows for consistent identification of the main trunk of the facial nerve at the outset of this procedure.





Preoperative Period


History of Present Illness





  • Pain, gradual onset of facial paralysis, rapid growth, and fixation are suggestive of a malignant tumor.



  • A history of radiation exposure increases the risk of mucoepidermoid carcinoma; a prior history of lymphoma or Sjögren disease should place lymphoma higher in the differential diagnoses.



  • A history of skin cancer or nonhealing skin lesions



  • Family history is not usually contributory, but there are case reports of familial parotid malignancies in the literature.



  • Social history of smoking in a patient with a cystic parotid mass makes a Warthin tumor a likely possibility.



  • A long history of a parotid mass may pose a higher risk of malignancy. Malignant degeneration occurs in 5% to 10% of pleomorphic adenomas; although the risks are not well defined, a long-term history or recurrence of pleomorphic adenomas may point to an increased prevalence of carcinoma ex pleomorphic adenoma.






  • History of previous parotid surgery.



  • Medications—use of nonsteroidal anti-inflammatory drugs (NSAIDs) and/or vitamin/herbal supplements or aspirin may contribute to prolonged bleeding and should be stopped 1 week prior to surgery.



Physical Examination





  • A mobile mass is suggestive of a benign tumor. Fixation is worrisome but may occur in benign tumors that extend through the stylomandibular tunnel into the prestyloid parapharyngeal space or that are inflamed.



  • Cervical lymphadenopathy is concerning for malignancy but occasionally may result from an inflammatory process.



  • Paralysis of one or more branches of the facial nerve is a hallmark of malignancy.



  • There may be evidence of previous surgery in the parotid area.



Imaging





  • Computed tomography (CT) or magnetic resonance imaging (MRI) with contrast is indicated to evaluate the anatomy, tumor extension and characteristics, presence of lymphadenopathy, and sialoliths.



  • MRI is particularly useful in the evaluation of parotid neoplasms.




    • Lesions with irregular borders, infiltration into soft tissue, and low signal intensity on T2-weighted images should raise suspicion of malignancy.



    • Recent studies have demonstrated the usefulness of MRI in identifying malignant tumors because they enhance earlier and have less “washout” at longer relaxation times.



    • Pleomorphic adenomas may be heterogeneous and have sharp scalloped borders.



    • Warthin tumors are cystic and have high signal intensity on T2 imaging.




  • Positron emission tomography (PET) is indicated for staging a known malignancy.



  • Ultrasound is useful for identifying enlarged intraparotid lymph nodes. If normal architecture is preserved, surgery may be avoided.



Indications





  • Neoplasms of the superficial lobe



  • Chronic parotitis refractory to medical management



Contraindications





  • Patient is a poor surgical candidate owing to medical history



  • Involvement of the deep lobe



  • Malignant tumor extending into the parapharyngeal space, mandible, skin, or ear canal or the presence of distant metastases



Preoperative Preparation


Biopsy





  • Fine-needle biopsy (FNA) is indicated in the case of any suspicious tumor.



  • The false-positive rate of FNA is about 10%.



  • Frozen section analysis has lower false-positive results (5%) and is used to confirm the diagnosis and evaluate margins.



  • FNA results are useful in managing salivary gland tumors in patients who are elderly and/or have significant medical contraindications to surgery.



  • Open biopsy should be used with caution owing to risk to the nerve or seeding of tumor. However, with a large mass in the tail of the parotid extending beyond 1 cm posterior to the ascending ramus, a small incision can be made parallel to the ramus, 1 cm posterior to it, to obtain tissue for flow cytometry and pathology. This technique is very useful in elderly patients with lymphoma and can be performed in the office.





Operative Period


Anesthesia





  • General anesthesia



  • Avoidance of long-acting paralytic agents



Positioning





  • The entire side of the face and ear is prepped and draped into the field after the neck is gently extended.



Perioperative Antibiotic Prophylaxis





  • Prophylactic use of antibiotics in patients undergoing parotidectomy for tumor removal is not indicated.



  • Suction drains are not an indication for antibiotics.



  • Antibiotics are indicated in surgeries performed for chronic parotitis.



Monitoring





  • Facial nerve monitoring is not considered the standard of care but is often used, especially in revision cases or chronic parotitis.



Instruments and Equipment to Have Available





  • Head and neck set



  • Facial plastics set



  • Blunt-tipped dissecting scissors



  • Right-angle retractors



Key Anatomic Landmarks





  • Cartilaginous “pointer” external auditory meatus



  • Mastoid tip



  • Posterior belly of the digastric muscle



Prerequisite skills





  • Nerve dissection



Operative Risks





  • Numbness of the ear and/or skin of the face and neck



  • Gustatory sweating (Frey syndrome); drainage from the wound and sialocele formation



  • Facial nerve injury



    • a.

      The risk of injury to the facial nerve and its significance must be discussed with all patients.


    • b.

      Patients who have malignant tumors must be informed of the plan regarding nerve sacrifice and reconstruction.




Surgical Technique


Incision



Apr 3, 2019 | Posted by in OTOLARYNGOLOGY | Comments Off on Superficial Parotidectomy
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