What are the indications, procedure steps, and major neurovascular structures to identify in a parotidectomy?

Indications and Procedure Steps for Parotidectomy with Key Neurovascular Structures

Parotidectomy is the primary treatment for salivary gland malignancies, with the extent of surgery determined by tumor characteristics including size, grade, and location relative to critical neurovascular structures. 1

Indications for Parotidectomy

• Salivary gland malignancies (primary treatment in resectable cases without distant metastases) 1
• Benign parotid tumors (pleomorphic adenoma being most common) 2, 3
• Metastatic disease to parotid lymph nodes (commonly from cutaneous squamous cell carcinoma) 4, 5
• Selected inflammatory parotid conditions 4

Preoperative Evaluation

• Fine needle aspiration biopsy (FNAB) with risk of malignancy (ROM) reporting using Milan System for Reporting Salivary Gland Cytopathology 1
• Imaging studies to determine tumor extent and relationship to facial nerve 1
• Assessment of facial nerve function (critical for surgical planning) 1, 6
• Consideration of ancillary testing (IHC or molecular studies) on FNAB specimens to support diagnosis 1

Procedure Steps and Surgical Approach

Extent of Surgery Based on Tumor Characteristics:

• For T1-T2 low-grade superficial tumors:

  • Partial superficial parotidectomy is appropriate 1, 6
  • Complete excision with preservation of uninvolved parotid tissue 1

• For high-grade or advanced (T3-T4) tumors:

  • At least superficial parotidectomy with consideration of total/subtotal parotidectomy 1
  • More extensive resection due to risk of intraparotid nodal metastases 1

Facial Nerve Management:

• Preservation principles:

  • Preserve facial nerve when preoperative function is intact and dissection plane can be created between tumor and nerve 1, 6
  • Intraoperative frozen section may guide extent of resection but should not be sole basis for facial nerve sacrifice 1

• Indications for facial nerve resection:

  • Preoperative facial nerve weakness/paralysis 1
  • Nerve branches encased or grossly involved by confirmed malignancy 1

Surgical Margins:

• Aim for complete excision with adequate free margins 1
• For low/intermediate-grade tumors, even narrow margins (≤5mm) show excellent disease control in absence of adverse features 1
• Margin status significantly affects overall survival 1

Major Neurovascular Structures to Identify

• Facial nerve (CN VII) - primary structure to identify and preserve when possible 1, 6

  • Main trunk emerges from stylomastoid foramen
  • Divides into temporofacial and cervicofacial divisions
  • Further branches into temporal, zygomatic, buccal, marginal mandibular, and cervical branches

• Greater auricular nerve - sensory nerve commonly sacrificed during parotidectomy, resulting in earlobe numbness 7

• External carotid artery and branches - provide blood supply to parotid gland 5

  • Superficial temporal artery
  • Maxillary artery

• Retromandibular vein - major venous drainage, important landmark during dissection 4

Potential Complications

• Facial nerve injury (temporary partial palsy in up to 20% of cases) 4, 7
• Frey syndrome (gustatory sweating) 7
• Wound complications (infection 2.3%, hematoma 3.5%, seroma 6.6%) 4
• Salivary fistula 7
• Tumor recurrence 7

Special Considerations

• Intraoperative frozen section has 98.5% sensitivity and 99% specificity for detecting malignant parotid tumors 1
• Decisions that would result in major harm (such as facial nerve sacrifice) should not be based on indeterminate preoperative or intraoperative diagnoses alone 1
• For benign tumors, extracapsular dissection may be considered as an alternative to formal parotidectomy in selected cases 2