The procedure is performed under general anesthesia with the endotracheal tube fixed to the contralateral side. Anesthesia team should be advised to avoid muscle relaxants because facial nerve function needs to be monitored. The neck is slightly extended, and the head turned away from the operated side. Half of the face is scrubbed with an antiseptic solution with care taken not to damage the eye. Drapes are placed with care to expose the hemiface and neck. If a nerve integrity monitor (NIM) is to be used, four electrodes are placed in the area of the temporal, zygomatic, buccal, and marginal mandibular branches of the facial nerve. Most surgeons prefer the modified Blair incision starting in a preauricular skin crease, around the lobule posteriorly, and extending inferiorly into a cervical skin crease. Some amount of skin should be left around the lobule to avoid pixie-ear (or satyr) deformity. An alternative is the modified facelift incision, which starts of similar to a modified Blair incision, however, after turning around the lobule, it extends posteriorly and superiorly into the retroauricular crease to continue within the occipital hairline.[27][28]

After incising the dermis and platysma, an anterior skin flap is raised in a plan between the SMAS and the superficial capsule of the parotid. A flap as thick as possible is advised to minimize the risk of Frey's syndrome as well as skin necrosis. Some surgeons advocate dissection in a plan just deep the superficial parotid fascia to further decrease the risk of Frey syndrome. Another option is to raise a supra-SMAS flap, taking care not to injure the subdermal plexus, and then raise a second, SMAS, flap in the style of a facelift. This SMAS flap can then be re-attached to minimize cosmetic deformity as well as Frey syndrome. Care is taken anteriorly not to damage branches of the facial nerve that become superficial at this level.[1]

Classically, the greater auricular nerve is sacrificed during the procedure; however, it is often possible to preserve its posterior branch. This is done by careful dissection along the nerve after its identification while raising the cervical subplatysmal flap; at the level of the bifurcation, the anterior branch is divided. If the entire nerve is to be sacrificed, this should be done as distal as possible to preserve a lengthy segment in case it is needed as a cable graft for facial nerve reconstruction (figure 4). The assistant plays a crucial role during the procedure by monitoring the face for muscle contractions even if a NIM is used, remembering the NIM and bipolar are good servants but bad masters (the surgeon should rely on direct observation before solely relying on electronic devices). Skin flaps are retracted and fixed with silk sutures or other retractive methods. Next, the tail of the parotid is dissected from the anterior border of the SCM muscle. The external jugular vein might be divided and ligated, though it can also frequently be preserved, as this might decrease bleeding during the procedure or provide a vessel for anastomosis for reconstructive flaps.[1]

The tail of the parotid is retracted superiorly, and the digastric muscle is identified. It serves as a landmark for the facial nerve, Saha, et al., measured the distance between the insertion of the posterior belly of the digastric over the mastoid and the facial nerve trunk and found it to be around 8 mm. The posterior belly of the digastric inserts into the mastoid tip, so tissue superficial to this structure can be divided with relative impunity once the distal marginal mandibular branch has been located. Dissection cephalad to the digastric muscle might injure the facial nerve as it exits the stylomastoid foramen between the mastoid and styloid processes. The attachments of the gland to the cartilage of the external auditory canal and the SCM muscle are divided to allow rotation and mobilization of the gland, a crucial step for identification of the facial nerve. A useful trick in adults is to palpate the mastoid tip and remove the non-salivary gland tissue overlying it and attached to the parotid. This can be done safely without concerns of facial nerve injury. Doing this in children is ill-advised since the mastoid tip is not well developed, placing the facial nerve at risk. The cartilage of the external auditory canal is dissected up to the level of the tragal pointer, another landmark for identification of the main trunk of the facial nerve, which is located roughly 1 cm inferior and anterior to it. Please note that the pointer is a cartilaginous structure that can be fractured or dislocated during the dissection; this factor needs to be taken into consideration when used as a landmark for the facial nerve. At this point, the surgeon can palpate the tympanomastoid suture. Emphasis is on palpation since it is often difficult to visualize the suture properly. It is considered the most consistent and reliable landmark for the main trunk of the facial nerve, which emerges a few millimeters deep to its lateral edge. Bushey et al. reported a mean distance between the facial nerve and the tympanomastoid suture of 4.9 mm.[29][30]

At this point the surgeon should have dissected the attachments of the gland from the external auditory canal, the SCM muscle, identified the digastric muscle, the tragal pointer, the tympanomastoid suture and is ready to begin the delicate and tedious task of identification of the facial nerve and the dissection along its branches (Figure 5). With a fine hemostat, the main trunk of the facial nerve is located and followed distally. It is important to dissect directly atop the nerve to visualize it the entire time directly. Divide the parotid tissue overlying the area of the facial nerve that has been dissected, never beyond that area. This can be done with fine scissors or an #12 blade while the glandular tissue is splayed with the hemostat. Hemostasis is ensured with bipolar diathermy and fine ties (when tightening the knots, care must be taken not to apply pressure on the facial nerve and its branches with the tightening finger). Once the pes anserinus is reached, it is advisable to visualize the entire portion of the facial nerve proximal to it to ensure that no early-branching occurred. Continue dissection along the branches of the facial nerve. Unless a complete superficial parotidectomy is planned, dissect only along branches proximal to the tumor. During the process, the retromandibular vein is often encountered deep to the facial nerve. When removing the superior part of the gland, the superficial temporal artery may need to be ligated; if so, this is performed just anterior to the auricle. When dissection continues anteriorly, the parotid duct is reached and divided if necessary. Remember that the buccal branch of the facial nerve is adjacent to the duct. Eventually, the tumor is removed with a cuff of parotid tissue or the entire superficial lobe.

When removing the deep lobe of the parotid, the surgeon can remove the superficial lobe completely or simply free it while keeping it attached anteriorly, reflecting it away and replacing it at the end of the procedure. Branches of the facial nerve are released from the tissue of the deep lobe with blunt and sharp dissection (figure 1). The tumor can be removed either through splayed branches of the facial nerve or by retracting it the mass inferiorly. If this proves to be difficult or inadequate, the transcervical approach with the division of the stylomandibular ligament provides excellent exposure of the parapharyngeal space, which includes the deep lobe of the parotid. Orabi et al. managed to removed 9 out of 9 benign tumors of the parapharyngeal space by dividing the stylomandibular ligament and retracting the mandible anteriorly. Vascular structures that need to be ligated and divided when necessary while maneuvering within the parapharyngeal space can include the external carotid, deep transverse facial and superficial temporal arteries, and the retromandibular and superficial temporal veins.[31]

Of note, when performing total parotidectomy for chronic parotitis, Stenson's duct needs to be followed up to the oral mucosa to avoid retention of any stones within a distal stump, which might lead to subsequent infection.

Benign tumors can almost always be dissected free from the facial nerve without problems. Even with pleomorphic adenoma where a certain margin is required to avoid recurrence, preservation of the facial nerve is always the rule and have a near-zero risk of recurrence when resected via true superficial parotidectomy. However, some malignant tumors might invade the nerve and raise the question of the sacrifice of the invaded branch. If preoperative facial paralysis exists, every attempt should be made to resect the tumor completely, even if it included resection of a segment of the facial nerve. When no preoperative paralysis is documented, it is acceptable to shave the tumor off the nerve (R1 resection), though many authors advocate resection of the affected branches and primary cable grafting. Isolated midfacial branches might not need to be repaired because the resulting deformity is often unnoticed.[14][32]

In the event of tumor spillage, when operating on a pleomorphic adenoma, the substance should be suctioned, and the site of capsule rupture closed. Some experts recommend against site irrigation since it might spread tumor cells all over the field. This spillage is believed to increase the risk of recurrence; however, there is no data to support this claim as of yet. The role of adjuvant radiotherapy in this setting is not clear.[19]

Before closure, the integrity of the facial nerve is checked, and function can be assessed with a nerve stimulator. Judicious nerve stimulation is advised since excessive electric stimulation might lead to neuropraxia. Sometimes mechanical trauma induces neuropraxia, and twitches are not observed. After meticulous hemostasis, a suction drain is inserted, and the wound closed in 2 layers.

In the recovery room, facial nerve function should be assessed as soon as possible. Some facial weakness is to be expected, particularly in total parotidectomy. This typically resolves with time so long as all branches were definitively identified and preserved, though full recovery can take many months.

The drain is left in place until the output is less than 15 to 50 cc in 24 hours. Duration of compressive dressing is variable, and some experts remove it when drain can be removed; others insist on the importance of a compressive dressing, especially after drain removal.

Coniglio et al. reported their experience with outpatient drainless parotidectomy. They established the viability of this approach in a properly selected patient[33]:

• Extracapsular parotidectomy with identification of selected branches of the facial nerve when needed without identification of the main trunk
• Minimal SMAS disruption and reconstruction at the end of the procedure primarily
• When SMAS reconstruction is not possible, grafting material was used to fill the dead space
• Jaw-bra for 48 hours and then overnight as tolerated

Hematoma: 0.9%. Meticulous hemostasis is the key to prevention, surgical reintervention to control bleeders.[34]

Facial paralysis: when anatomically identified and branches are known to be intact, the most probable cause of the paralysis is stretching. Incidence of transient paralysis is somewhere between 16.6% to 34%, and 90% will recover within 1 month; however, it could last as long as 18 months. Ability to close the eye without any corneal exposure needs be assessed and preventive measures should be taken to prevent exposure keratitis: ophthalmic drops and ointments, ophthalmologist consultation, gold weights, botulinum toxin are all potential treatment options in this interim.[35][36]

Seroma: managed by needle aspiration and compression dressing.[36]

Surgical site infection: prophylactic antibiotics are controversial. Extensive procedures with neck dissection +/- free flap reconstruction are at higher risk of infection and benefit from perioperative antibiotics. In more standard parotidectomy, intraoperative antibiotics are sufficient in most patients.

Frey’s syndrome: more accurately referred to as gustatory sweating. Patients report facial swelling and sweating at the site of the parotidectomy in occurrence with meals. Etiology is believed to be aberrant innervation of sweat gland with branches from the GAN after its division during surgery. This provides parasympathetic innervation to the normally sympathetic-innervated sweat glands. Diagnosis is made using the post-operative iodine-starch test (Minor test), where iodine starch placed on the affected area turns blue signaling sweat secretion. The incidence historically has been reported as high as 50 to 100%, though, with modern techniques and the use of SMAS flaps and thicker skin flaps at the time of initial elevation, this is greatly, greatly reduced. Should this develop, surgical treatment options can be disappointing, with the best results obtained using SMAS and superficial temporal artery flaps as a barrier between the surgical site and the skin. Gold standard treatment now is botulinum toxin injection. Relief of symptoms is obtained for 11 to 36 months. It works at the pre-synaptic level of the neuromuscular and neuroglandular junction by blocking the release of acetylcholine.[36][37]

First bite syndrome (FBS): painful spasm in the parotid region occurring at the first bite during mastication and decrease afterward. This pain accompanies each meal usually. It is a unique complication of surgeries targeting the deep lobe of the parotid gland, the parapharyngeal space, and the infratemporal fossa. Presumed etiology is the loss of sympathetic innervation of the parotid gland, which will lead to parasympathetic overshooting, resulting in contraction of parotid myoepithelial cells. This is supported by the fact that Linkov et al., only had one case of FBS when the entire parotid gland was removed. This case had ectopic parotid tissue left in place. Leaving the superficial lobe in place was found to carry a higher risk of FBS. Treatment is often challenging and begins with carbamazepine, which must be titrated. Most patients report improvement with time but never complete recovery. This is thankfully exceedingly rare, and really only encountered in extensive parotidectomy and extended neck dissections that violate the deep fascia of the floor of the neck, traumatizing the superior cervical ganglion.[38]

Loss of sensation around the ear, especially the lobule, occurs frequently. Significant but incomplete improvement is expected within one year. Preservation of the posterior branch of the great auricular nerve will hasten recovery.[36]

Amputation neuroma might occur when the GAN is transected; treatment is by simple excision.[36]

Surgical site depression occurs proportionally to the amount of tissue resected. Reconstruction with an SCM flap is helpful, but it has the drawback of creating a defect in the neck. An autologous fat graft can also be used.[36]

Trismus: inflammation of the master muscle, transient, and mild.[36]

Sialocele, or salivary fistula, is the result of the communication of a salivary duct or the gland with the skin. Saliva will be excreted through the wound. The incidence of this complication is between 4% and 14%. Treatment is by applying frequent drainage and compressive dressing. Sometimes decreasing oral intake is necessary; even completion parotidectomy has been suggested. Botulinum toxin injection offers a good therapeutic outcome by blocking salivary flow.[36]

Medical treatment plays a minor role when it comes to the treatment of most parotid diseases, therefore surgical intervention remains the cornerstone of treatment. Parotidectomy is an intricate procedure with functional, aesthetic, and potentially oncologic considerations. Knowledge of pertinent anatomy, preoperative optimization, techniques for identification of the facial nerve, and complications will allow the surgeon to safely and effectively care for patients requiring parotidectomy.

Parotid surgery is an emotionally intense experience for the patient and the family, with most fearing postoperative disfigurement. Fortunately, the results are frequently excellent for experienced surgeons. It is the physician’s duty to explain clearly to the patient what to expect, tailoring such discussions to the scenario of each individual patient. A small benign lesion may less likely result in permanent facial paralysis but is most dependent upon its location within the gland itself. An extensive malignant tumor poses a significant risk for facial nerve injury. An interdisciplinary approach is crucial to success. A free flap surgeon is consulted when significant resection is expected to discuss the pros and cons of vascularized tissue reconstruction versus local flap reconstruction. Nurses familiar with head and neck surgery are the keystone to an optimal postoperative outcome. They can recognize a hematoma that needs urgent drainage, a seroma, or a salivary fistula. The role of the radiologist and the pathologist cannot be overemphasized. Preoperative delineation of the tumor by an experienced radiologist can minimize surprises during surgery and help tremendously when counseling the patient since the surgeon had a clear idea of what type of parotidectomy he will be performing. A pathologist familiar with salivary glands is essential for accurate interpretation of FNAC, which allows appropriate patient counseling and might advise and wait a see approach in some cases like a Warthin tumor. When the diagnosis of malignancy is confirmed or in the event of spillage of pleomorphic adenoma during surgery, a radiation oncologist is consulted to discuss the need for adjuvant radiotherapy.[39][19][11][18]