What is the complete operative technique for superficial parotidectomy?

Operative Technique for Superficial Parotidectomy

Preoperative Assessment

Superficial parotidectomy requires meticulous identification and preservation of the facial nerve while achieving complete tumor excision with adequate margins. 1, 2

Essential Preoperative Evaluation

• Perform fine needle aspiration biopsy (FNAB) using the Milan System for Reporting Salivary Gland Cytopathology to determine risk of malignancy 2
• Obtain imaging studies (CT or MRI) to assess tumor extent and relationship to facial nerve branches 2
• Document baseline facial nerve function thoroughly, as this determines surgical approach and nerve preservation strategy 2
• Consider ancillary testing including immunohistochemistry or molecular studies on FNAB specimens when diagnosis is uncertain 2

Patient Positioning and Incision

Positioning

• Position patient supine with head turned away from operative side 3, 4
• Ensure adequate exposure of entire parotid region and neck 3

Incision Technique

• Use modified facelift (Blair) incision: begin in preauricular crease, extend around earlobe, and continue posteriorly into hairline along occipital hairline 5
• Alternatively, extend incision inferiorly along anterior border of sternocleidomastoid muscle if neck dissection is planned 2
• Raise skin flaps anteriorly to expose parotid gland, preserving greater auricular nerve when possible 5

Facial Nerve Identification and Dissection

Main Trunk Identification

The facial nerve main trunk must be identified at the stylomastoid foramen as the critical first step. 2, 4

• Locate the main trunk emerging from stylomastoid foramen using anatomic landmarks: 2
  • Tragal pointer (cartilaginous projection pointing toward nerve)
  • Posterior belly of digastric muscle
  • Tympanomastoid suture line
• Dissect carefully in plane between parotid tissue and nerve using blunt dissection technique 4
• Identify division into temporofacial and cervicofacial divisions 2

Nerve Preservation Strategy

Preserve the facial nerve when preoperative function is intact and a dissection plane can be created between tumor and nerve. 1, 2

• For benign or low-grade tumors, maintain dissection plane between nerve branches and tumor capsule 2
• Dissect only the nerve division adjacent to the tumor rather than exposing all branches unnecessarily 4
• Use nerve stimulator to confirm nerve identity when anatomy is unclear 3

Indications for Nerve Resection

• Resect facial nerve branches only when: 1, 2
  • Preoperative facial nerve weakness or paralysis is present
  • Nerve branches are grossly encased or infiltrated by confirmed malignancy on frozen section
  • Complete margin clearance cannot be achieved otherwise

Extent of Parotid Tissue Resection

For T1-T2 Low-Grade Tumors

Perform partial superficial parotidectomy removing only parotid tissue surrounding the tumor, not the entire superficial lobe. 1, 2

• Excise tumor with surrounding parotid parenchyma achieving negative margins (≥1mm) 1
• Additional excision of uninvolved parotid tissue is unnecessary, as narrow margins (≤5mm) show excellent disease control (90.6% 5-year DFS) in low/intermediate-grade tumors without adverse features 1
• Enucleation may be necessary when tumor is immediately adjacent to nerve branches, though this carries slightly higher recurrence risk 4

For High-Grade or T3-T4 Tumors

Perform at least complete superficial parotidectomy with consideration of total/subtotal parotidectomy due to risk of intraparotid nodal metastases. 1, 2

• Remove entire superficial lobe including intraparotid lymph nodes 1
• Consider removing additional deep lobe tissue if accessible without significantly increasing facial nerve risk 1
• The 3.7% parotid bed recurrence rate with adjuvant radiation does not differ based on extent of parotidectomy, supporting superficial parotidectomy as adequate when combined with adjuvant therapy 1

Intraoperative Frozen Section

• Obtain frozen section for definitive diagnosis when preoperative FNAB is indeterminate 2
• Frozen section has 98.5% sensitivity and 99% specificity for detecting malignant parotid tumors 2
• Do not base major decisions like facial nerve sacrifice solely on indeterminate frozen section results 2
• Use frozen section to assess margin adequacy when malignancy is confirmed 2

Hemostasis and Wound Closure

Hemostasis

• Achieve meticulous hemostasis throughout dissection to minimize hematoma risk 5
• Ligate or cauterize external carotid artery branches (superficial temporal, maxillary arteries) as encountered 2

Closure Technique

• Consider superficial musculoaponeurotic system (SMAS) flap reconstruction to reduce Frey syndrome incidence 5
• Place suction drain in parotid bed 5
• Close skin in layers with attention to cosmetic result 5

Critical Surgical Pitfalls

Facial Nerve Injury Prevention

• Temporary facial paresis occurs in 15-77% of cases but resolves in 94.9% by 6 months and 100% by 12 months 5
• Permanent facial nerve injury occurs in only 2.5% when nerve is intentionally preserved 3
• Risk factors for increased temporary paresis include: 5
  • Tumor location in superior lateral superficial lobe
  • Tumor size >2cm
  • Prolonged operative time >165 minutes

Margin Adequacy

• Achieving negative surgical margins (≥1mm) significantly improves overall survival in malignancies 1
• Close margins (≤5mm) are acceptable for low/intermediate-grade tumors without adverse features (perineural invasion, lymphovascular invasion, nodal disease) 1
• Recurrence rate with appropriate technique is 0.8-1% for benign tumors 3, 4

Frey Syndrome Prevention

• Frey syndrome (gustatory sweating) occurs in 4-27.7% of patients 4, 6
• SMAS flap interposition reduces incidence 5
• Inform patients preoperatively as this is the most common long-term complication 6