Townsend Courtney M.Jr., Evers B. Mark. Atlas of General Surgical Techniques: Expert Consult

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Sternocleidomastoid muscle

Great auricular nerve branches

Digastric muscle (posterior belly)

Mastoid tip

FIGURE 4 –3

CHAPTER 4 • Parotidectomy

2. DISSECTION

◆ For a parotidectomy to be performed safely, wide exposure and knowledge of important

anatomic landmarks are key.

◆ The operation begins in the plane deep to the tail of the parotid. The fascia along the

anterior border of the SCM muscle is incised, exposing the muscle toward the level of the

mastoid process. Electrocautery can be used in this dissection (Figure 4-3).

◆ The great auricular nerve and external jugular vein are identiﬁ ed at this time. If the nerve

has multiple branches, the posterior branch is preserved to maintain sensation to the

external ear. Maximal nerve length is dissected in the event that it is needed for a facial

nerve graft (see Figure 4-3).

◆ As the dissection proceeds anteriorly, the tail of the parotid is dissected from the SCM

muscle and mastoid process, and the posterior belly of the digastric muscle is exposed. The

gland is retracted using an Allis clamp or hemostats (see Figure 4-3).

◆ The posterior belly of the digastric muscle is further exposed toward its origin by retracting

the SCM muscle posteriorly and both sharply and bluntly dissecting the tissue overlying the

muscle (see Figure 4-3).

56 Section I • Head and Neck and Endocrine Procedures

◆ The posterior aspect of the gland is now dissected from the external auditory canal. The

parotid tissue is carefully bluntly and sharply dissected from the ear canal using a ﬁ ne curved

hemostat or scissors and bipolar cautery to maintain hemostasis. It is critical to maintain abso-

lute hemostasis in order to identify the facial nerve trunk without injury (Figure 4-4).

◆ Once the parotid gland is freed from its ﬁ brous attachments, blunt dissection along the ear

canal perichondrium using a ﬁ nger will allow the surgeon to palpate the bony-cartilaginous

junction of the ear canal, the tympanomastoid ﬁ ssure, and the tragal pointer (see Figure 4-4).

◆ The main trunk of the facial nerve is now close by. It is approximately 1 cm deep to the tip

of tragal pointer (anterior and inferior), 6 to 8 mm below the end of the tympanomastoid

ﬁ ssure (groove palpated separating the mastoid tip from the tympanic portion of the

temporal bone), and just above and on the same plane as the attachment of the digastric

muscle in the digastric groove.

◆ The remaining bridge of parotid tissue located between the superior border of the posterior

belly of the digastric muscle and the external auditory ear canal is now dissected. The

mobilized portions of the parotid gland are retracted anteriorly, putting the residual parotid

tissue on stretch. A retractor is placed so that the posterior belly of the digastric muscle is

also exposed during this dissection. This tissue is bluntly and sharply dissected, layer by

layer, to expose the junction of the superior aspect of the posterior belly of the digastric

muscle and the tympanomastoid ﬁ ssure. The tips of the dissecting instrument face upward

and dissection is done along a broad front (see Figure 4-4).

◆ Once the temporoparotid fascia, which runs from the tympanomastoid ﬁ ssure to the

gland, is transected, the parotid tissue is released and the facial nerve will be easily

identiﬁ ed (see Figure 4-4).

◆ The nerve stimulator should be used only if there is a question as to the identity of the

main trunk of the facial nerve (see Figure 4-4).

◆ Following identiﬁ cation of the main trunk, dissection proceeds in a plane superﬁ cial to the

nerve. A curved hemostat or scissors, with tips facing upward, is used to spread the tissue

immediately superﬁ cial to the nerve, keeping the nerve under direct vision at all times. The

main trunk is dissected anteriorly until the pes anserinus is reached. The upper (zygomati-

cotemporal) and lower (cervicofacial) divisions are identiﬁ ed (Figure 4-5).

CHAPTER 4 • Parotidectomy

Deep lobe of

parotid gland

Tumor in tail of

superficial parotid lobe

Parotid duct

Sternocleidomastoid muscle

FIGURE 4 –5

Sternocleidomastoid

muscle

Main trunk facial nerve

Digastric muscle (posterior belly)

Cartilage of

external

auditory canal

Tympanomastoid

suture line

FIGURE 4 –4

58 Section I • Head and Neck and Endocrine Procedures

◆ Dissection of individual facial nerve branches to the periphery of the gland is performed in

an orderly fashion. Dissection can proceed from inferior to superior or superior to inferior,

depending on tumor location (Figure 4-6).

◆ A ﬁ ne curved hemostat or scissors is used to dissect just on top of the nerve, elevating the

parotid tissue off the nerve. The instrument is opened, spreading the parotid tissue and ex-

posing the nerve. The tissue is cut in a horizontal plane parallel to the nerve. If the nerve is

not visualized, do not cut the tissue! Once a nerve branch is completely exposed, the sur-

geon again returns to the major division where he or she was working and the next nerve

branch in sequence is exposed. This is done until all the branches are exposed and the

gland is removed. The parotid tissue is retracted forward using Allis clamps and other

retractors during this dissection (see Figure 4-6).

◆ In this example, the benign tumor is located in the tail of the parotid. The branches of the

lower division are dissected and the tumor is removed with a large cuff of parotid tissue. Care

should be taken to avoid injury to the marginal mandibular branch when ligating the posterior

facial vein. In addition, the “ﬂ anking maneuver” (swinging around the tail of the parotid)

should also be avoided because it may also result in injury to the marginal mandibular branch

(most common site of injury). A complete superﬁ cial parotidectomy with dissection of all of

the upper division nerve branches is unnecessary in this case (Figure 4-7).

CHAPTER 4 • Parotidectomy

Parotid duct

FIGURE 4 –7

Buccal, mandibular, and cervical

branches of facial nerve

FIGURE 4 –6

60 Section I • Head and Neck and Endocrine Procedures

3. DEEP LOBE PAROTIDECTOMY

◆ All branches of the upper and lower divisions of the facial nerve are systematically dissected,

and the entire lateral lobe of the parotid is removed when the tumor located in the lateral

lobe dictates it and in cases in which a total parotidectomy is required (deep lobe tumor, ma-

lignancy, chronic parotitis). The superﬁ cial lobe is sent as a separate specimen (Figure 4-8).

◆ Stensen’s duct is transected at the anterior border of the gland and ligated. Care is taken not

to injure the buccal branch of the nerve that runs parallel to Stensen’s duct (see Figure 4-8).

◆ To remove the deep lobe of the parotid, the surgeon very delicately and meticulously

dissects the main trunk of the facial nerve and its branches to free them from the deep lobe.

◆ After each branch is completely freed from the deep lobe, the surgeon uses gentle retraction

using a vein retractor, nerve hook, or very small vessel loops to lift the nerves, allowing

blunt and sharp dissection and mobilization of the deep lobe. Excessive retraction of the

nerves will result in a stretch injury (see Figure 4-8).

◆ The gland may be dissected from the stylohyoid and stylopharyngeus muscles. During dis-

section of the deep lobe the following vessels may be encountered: the superﬁ cial temporal

vessels, the internal maxillary artery (running deep to mandibular ramus), the occipital

artery, the posterior auricular artery, and the pterygoid plexus of veins. Bleeding can be

substantial, and patience must be used in identifying and controlling the bleeding vessel to

avoid inadvertent injury to the nerve (Figure 4-9).

◆ Removal of the deep lobe may be accomplished inferior to, superior to, or between facial

nerve branches (see Figure 4-9).

CHAPTER 4 • Parotidectomy

FIGURE 4 –9

Main trunk facial nerve

Deep lobe of

parotid gland

Upper division facial nerve

Lower division facial nerve

FIGURE 4 –8

62 Section I • Head and Neck and Endocrine Procedures

◆ A thin layer of masseter muscle (margin) is removed when dealing with recurrent benign tumors,

and a larger margin or the entire muscle is removed if the lesion is malignant (Figure 4-10).

◆ Stensen’s duct is followed through the buccinator muscle to the mucosa in cases of chronic

and recurrent sialadenitis associated with sialolithiasis (stones).

4. RADICAL PAROTIDECTOMY

◆ Radical parotidectomy (total parotidectomy with facial nerve sacriﬁ ce) is indicated in cases

of malignant involvement of the main trunk of the facial nerve. Sacriﬁ ce of one or all of the

peripheral nerve branches without sacriﬁ ce of the main trunk is indicated when the nerve

branches are involved but the main trunk is not.

◆ Intraoperative frozen section analysis are performed on all proximal and distal nerve stumps

to ensure negative margins. The branches are tagged with a ﬁ ne suture so that they may be

easily located intraoperatively for facial nerve grafting.

◆ Mastoidectomy may be necessary to obtain clear proximal facial nerve margins.

◆ The great auricular or sural nerve can be used to reconstruct the facial nerve. The main

trunk and the marginal mandibular, buccal, and temporal branches are reconstructed to re-

store oral competency and eye closure. However, reconstruction of the facial nerve branches

anterior to lateral canthus is not required.

Masseter muscle

FIGURE 4 –10

CHAPTER 4 • Parotidectomy

5. CLOSING

◆ The main trunk of the facial nerve is stimulated (0.5 mA) to prove that all branches are

intact before the wound is closed. If some or all of the branches do not respond to stimu-

lation, careful inspection to ensure anatomic integrity of nerve is performed.

◆ The skin is closed in two layers using fast absorbing versus monoﬁ lament suture. Care is

taken to accurately reapproximate the lobule.

◆ A 10-mm Jackson-Pratt drain is placed via a separate stab incision in the postauricular area.

Care is taken to avoid placement of the drain next to the nerve.

◆ A ﬁ gure-of-eight pressure dressing is placed around the neck, face, and head.

STEP 4: POSTOPERATIVE CARE

◆ Facial nerve function is evaluated as soon as the patient is awake and cooperative.

◆ If facial nerve paresis or paralysis is noted, steroids may be given only if the facial nerve is

known to be intact. If it is possible that the main trunk or nerve branch was transected

during surgery, immediate exploration and repair of nerve must be performed.

◆ Pressure dressing is removed the next morning.

◆ Closed suction drain is removed when output is less than 15 to 30 mL over 24 hours.

◆ If eye closure is poor (neuropraxia, nerve sacriﬁ ce), saline drops are used multiple times

per day, and Lacri-Lube and eye taping are prescribed nightly to prevent exposure keratitis.

STEP 5: PEARLS AND PITFALLS

◆ A nerve integrity monitor and magniﬁ cation (loupe or microscope) may be used to aid in

facial nerve identiﬁ cation and preservation, particularly in reoperations and cases of chronic

infection with scarring.

◆ Overuse of the facial nerve stimulator can cause neuropraxia.

64 Section I • Head and Neck and Endocrine Procedures

◆ If the tumor location precludes identiﬁ cation of the main trunk of the facial nerve using

standard techniques, the main trunk can be identiﬁ ed using retrograde dissection along the

temporal, buccal, or marginal mandibular branch (most common) or via mastoidectomy.

◆ Parotid specimen and/or lymph nodes are sent for intraoperative frozen section analysis if

malignancy is suspected.

◆ The posterior auricular artery or its branch can cross the main trunk of the facial nerve and

cause signiﬁ cant bleeding and inadvertent injury to the nerve if not properly identiﬁ ed and

ligated.

◆ Facial paralysis or paresis can result from aggressive dissection or inadvertent injury of the

nerve. Recovery of facial nerve paresis/paralysis can occur over 3 to 4 weeks if neuropraxic

injury and up to 1 year if axon death has occurred.

◆ Hematoma formation, manifested by acute postoperative pain, swelling of ﬂ ap, and oozing

from wound, demands reexploration and evacuation. Hematoma can cause airway compres-

sion if signiﬁ cant. Extreme care must be taken to avoid injury to the exposed facial nerve.

◆ Skin ﬂ ap necrosis is rare but can occur in heavy smokers and in the postauricular area

when the skin ﬂ ap is too thin and the skin incision is made at an acute angle.

◆ Frey’s syndrome (gustatory sweating) is associated with sweating in the area of skin overlying

the parotid bed. Most patients have this to some degree, and it is typically subclinical. It

occurs because of the aberrant regrowth of parasympathetic motor ﬁ bers from the auriculo-

temporal nerve into the sympathetic nerve ﬁ bers controlling sweat glands. Raising thicker

subcutaneous ﬂ aps may reduce its occurrence. Medical therapy includes topical

scopolamine. Surgical remedies are rarely successful (dermal graft, tympanic neurectomy).

◆ Postoperative sialocele or salivary ﬁ stula (salivary drainage from wound) is rare and can

usually be successfully managed with aspiration and compression dressings. Atropine-like

drugs may be beneﬁ cial.

SELECTED REFERENCES

1. Johnson JT: Parotid. In Myers EN, Carrau RL (eds): Operative Otolaryngology: Head and Neck Surgery,

1st ed. Philadelphia, Saunders, 1997, pp 504-518.

2. Olsen KD: Parotid superﬁ cial lobectomy. In Bailey BJ, Calhoun KH, Coffey AR, Neely JG: Atlas of Head &

Neck Surgery—Otolaryngology. Baltimore, Lippincott-Raven, 1996, pp 2-11.

3. Lore JM, Medina J: The parotid salivary gland and management of malignant salivary gland neoplasia. In

Lore JM, Medina J (eds): An Atlas of Head and Neck Surgery, 4th ed. Philadelphia, Saunders, 2005,

pp 861-891.

4. Olsen KD: Superﬁ cial parotidectomy. Oper Tech Gen Surg 2004;6:102-114.

5. Shah JP, Patel SG: Salivary glands. In Shah JP, Patel SG (eds): Head and Neck Surgery and Oncology,

3rd ed. Edinburgh, Mosby, 2003, pp 439-474.