Residency · Residency · Otolaryngology
Parotidectomy: Technique and Facial Nerve Preservation
Introduction
Parotidectomy is one of the most common operations performed by the otolaryngologist-head and neck surgeon. The procedure demands meticulous technique due to the intimate relationship of the facial nerve (CN VII) with the parotid gland. The facial nerve divides the parotid into superficial and deep lobes, and its identification and preservation is the central challenge of parotid surgery.
Surgical Anatomy
Parotid Gland
Largest salivary gland; weighs approximately 15-30 grams. Enclosed within the parotid-masseteric fascia (superficial layer of deep cervical fascia). Stensen duct exits anteriorly, crosses the masseter, pierces the buccinator, opens opposite the second upper molar. Contains intraparotid lymph nodes (drains external ear, scalp, facial skin).
Facial Nerve Course Through the Parotid
Exits the stylomastoid foramen. Enters the posterior surface of the parotid gland. Divides at the pes anserinus into two main divisions (temporofacial and cervicofacial). Five terminal branches: Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical (mnemonic: "Two Zebras Bit My Cat"). The buccal branch has the most anastomoses; injury is best tolerated. The marginal mandibular branch and temporal branch have the fewest anastomoses; injury causes the most noticeable deficits.
Landmarks for Facial Nerve Identification
Tragal pointer: nerve lies 1 cm deep and inferior to the tragal cartilage. Tympanomastoid suture: nerve exits just anterior and inferior to this suture line. Posterior belly of the digastric muscle: nerve lies superior to this muscle at the stylomastoid foramen. Retrograde identification: tracing a peripheral branch back to the main trunk when anatomy is distorted.
Indications for Parotidectomy
Benign neoplasms: pleomorphic adenoma, Warthin tumor. Malignant neoplasms: mucoepidermoid carcinoma, adenoid cystic carcinoma, others. Chronic parotitis refractory to conservative management. Intraparotid lymph node disease: metastatic skin cancer (melanoma, SCC). Diagnostic excision: indeterminate FNA results.
Types of Parotidectomy
| Procedure | Extent | Indication |
|---|---|---|
| Partial superficial parotidectomy | Extracapsular dissection of small tumor | Small, well-defined benign tumors |
| Superficial (lateral) parotidectomy | All tissue superficial to CN VII | Benign neoplasms, standard approach |
| Total parotidectomy (nerve preservation) | Superficial + deep lobe, CN VII preserved | Deep lobe tumors, high-grade malignancy |
| Radical parotidectomy | Total + CN VII sacrifice | Direct nerve invasion by tumor |
| Deep lobe only parotidectomy | Transcervical or transparotid | Isolated deep lobe tumors |
Superficial (lateral) parotidectomy: removal of parotid tissue superficial to the facial nerve. Total parotidectomy with nerve preservation: removal of superficial and deep lobe tissue while preserving the facial nerve. Radical parotidectomy: total parotidectomy with sacrifice of the facial nerve (for tumors directly invading the nerve). Partial (limited) superficial parotidectomy: extracapsular dissection or partial lateral parotidectomy for small, well-defined benign tumors. Deep lobe only parotidectomy: transcervical or transparotid approach for isolated deep lobe tumors.
Surgical Technique
Preoperative Considerations
Facial nerve monitoring: continuous EMG monitoring is standard of care. Mark the planned incision: modified Blair incision (preauricular extending postauricular and into the neck). Position: supine, head turned to contralateral side, eye visible in the field.
Step-by-Step Approach
Modified Blair incision: preauricular, curving behind the ear lobule, into a cervical skin crease. Raise a thick skin flap anteriorly over the parotid-masseteric fascia (superficial to SMAS). Identify the greater auricular nerve over the SCM — preserve the posterior branch when possible. Expose the anterior border of the SCM and posterior belly of the digastric. Identify the facial nerve main trunk using anatomic landmarks (tragal pointer, tympanomastoid suture, digastric). Dissect along the nerve branches from trunk to periphery, elevating the superficial lobe off the nerve. Maintain hemostasis with bipolar cautery only (never monopolar near the nerve). Complete excision of the superficial lobe with the specimen.
Deep Lobe Resection (if indicated)
After superficial lobectomy, gently retract nerve branches with vessel loops. Remove deep lobe tissue from between and beneath the nerve branches. Parapharyngeal space tumors may require mandibulotomy or transcervical approach.
Facial Nerve Management in Malignancy
Preserve the nerve unless directly invaded by tumor. If nerve sacrifice is required: immediate cable grafting (greater auricular nerve or sural nerve). Frozen section of proximal and distal nerve margins. Adjuvant radiation is indicated when the nerve is sacrificed or margins are close.
Complications
Facial nerve injury: temporary weakness in 10-30%, permanent in 1-4% for benign tumors. Frey syndrome (gustatory sweating): aberrant regeneration of parasympathetic fibers to sweat glands; occurs in 30-60%; treatment with antiperspirant, botulinum toxin, or interposition barrier. Greater auricular nerve injury: numbness of the ear lobule and preauricular skin. Salivary fistula/sialocele: usually self-limited; managed with aspiration and pressure dressing. Hematoma: risk of airway compromise; requires prompt evacuation. First bite syndrome: pain with first bite of a meal; related to loss of sympathetic innervation; more common with deep lobe or parapharyngeal surgery.
Key Clinical Pearls
Never use monopolar cautery near the facial nerve — bipolar only, and at a distance. The facial nerve is always lateral (superficial) to the retromandibular vein — this vein indicates the plane of the nerve. Enucleation of pleomorphic adenomas leads to unacceptable recurrence rates (20-45%); formal parotidectomy is required. If the nerve cannot be found anterograde, use retrograde dissection from a peripheral branch (commonly the marginal mandibular). Postoperative facial nerve weakness without transection will usually recover within 6-12 months.
References
- Witt RL. The significance of the margin in parotid surgery for pleomorphic adenoma. Laryngoscope. 2002;112(12):2141-2154.
- Marchese-Ragona R, De Filippis C, Marioni G, Staffieri A. Treatment of complications of parotid gland surgery. Acta Otorhinolaryngol Ital. 2005;25(3):174-178.
- Grosheva M, Klussmann JP, Grimminger C, et al. Electromyographic facial nerve monitoring during parotidectomy for benign lesions does not improve the outcome of postoperative facial nerve function. Laryngoscope. 2009;119(12):2299-2305.
- Lim YC, Lee SY, Kim K, et al. Conservative parotidectomy for the treatment of parotid cancers. Oral Oncol. 2005;41(10):1021-1027.