Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

FIGURE 3–12 FIGURE 3–13

Subcuticular sutures

FIGURE 3–14

SELECTED REFERENCES

1.Akerström G, Malmaeus J, Bergström R: Surgical anatomy of human parathyroid glands. Surgery 1984;95:14-21.

2.Bilezikian JP, Potts JT Jr, Fuleihan EH, et al: Summary statement from a workshop on asymptomatic primary hyperparathyroidism: A perspective for the 21st century. J Clin Endocrinol Metab 2002;87: 5353-5361.

3.Boggs JE, Irvin GL, Molinari AS, et al: Intraoperative parathyroid hormone monitoring as an adjunct to parathyroidectomy. Surgery 1996;120:954-958.

4.Roman SA, Sosa JA, Mayes L, et al: Parathyroidectomy improves neurocognitive deficits in patients with primary hyperparathyroidism. Surgery 2005;138:1121-1128.

5.Udelsman R, Donovan P: Remedial parathyroid surgery: Changing trends in 130 consecutive cases. Ann Surg 2006;243:471-479.

If malignancy or deep lobe involvement is suspected, imaging should be obtained.

Fine needle aspiration is 94% sensitive, 97% specific, and 95% accurate in diagnosis of parotid masses. Inconclusive lymphoid cells do not exclude lymphoma. Fine needle aspiration is useful for preoperative counseling.

Open biopsy is not recommended because of the risk of implantation of malignant cells and possible injury to the facial nerve. Open biopsy is indicated when malignancy is suspected (facial nerve paralysis, skin involvement) and diagnosis cannot be confirmed with fine needle aspiration.

If tumor is believed to be malignant, preoperative counseling should include possible facial nerve sacrifice, neck dissection, reconstruction of the facial nerve, and possible facial reanimation surgery.

Indications for lateral lobectomy include the following:

Benign or malignant tumor (exceptions include benign lymphoepithelial cysts and parotid lymphoma)

Refractory sialolithiasis, sialoadenitis (chronic parotitis), and chronic sialorrhea; some authors advocate total parotidectomy for chronic parotitis

As part of lymph node dissection for other head and neck primary tumors, primarily cutaneous malignancies of the face and scalp

Excision of first branchial cleft cyst involving parotid gland

Although superficial parotidectomy is performed for tumors located in the lateral lobe of the parotid, most authors now recommend excision of the tumor with a healthy cuff of normal gland, particularly if the tumor is located in the tail.

Enucleation of benign tumors is to be condemned. This increases risk of facial nerve injury, unacceptable risk of tumor recurrence, and increased difficulty of facial nerve preservation with repeat excision.

Total parotidectomy with facial nerve preservation is indicated for tumors arising from or extending to a plane deep to the facial nerve and for all mediumto high-grade malignant tumors, regardless of location.

Radical parotidectomy (total parotidectomy with facial nerve sacrifice) is indicated in cases of malignant involvement of the main trunk of the facial nerve.

Modified Blair incision

Great auricular nerve

Hyoid bone

External jugular vein

Thyroid cartilage

Sternocleidomastoid muscle

2005 M Cooley

FIGURE 4–1

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 identified 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).

Digastric muscle (posterior belly)

Mastoid tip

Sternocleidomastoid muscle

Great auricular nerve branches

FIGURE 4–3

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 fine curved hemostat or scissors and bipolar cautery to maintain hemostasis. It is critical to maintain absolute hemostasis in order to identify the facial nerve trunk without injury (Figure 4-4).

Once the parotid gland is freed from its fibrous attachments, blunt dissection along the ear canal perichondrium using a finger will allow the surgeon to palpate the bony-cartilaginous junction of the ear canal, the tympanomastoid fissure, 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 fissure (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 fissure. 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 fissure to the gland, is transected, the parotid tissue is released and the facial nerve will be easily identified (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 identification of the main trunk, dissection proceeds in a plane superficial to the nerve. A curved hemostat or scissors, with tips facing upward, is used to spread the tissue immediately superficial 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 (zygomaticotemporal) and lower (cervicofacial) divisions are identified (Figure 4-5).

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 fine 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 exposing 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 surgeon 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 “flanking 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 superficial parotidectomy with dissection of all of the upper division nerve branches is unnecessary in this case (Figure 4-7).