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Salivary gland tumors are uncommon, representing less than 4% of head and neck tumors. However, over 80% of these tumors arise from the parotid gland making parotid dissection an important tool for training surgeons to practice. Due to the rarity of these tumors and need for long-term follow up, specialized centers treat many of these patients. It is vital for surgeons to have a simplified, adaptable approach to parotid dissection. Additionally, a standardized approach to parotid dissection enables surgeons to adapt to different mass characteristics, which may become apparent during a case. In the video, we present a standard approach to parotid dissection using a cadaver. The patient described in the manuscript is a hypothetical case, and the information does not belong to the cadaver.
parotid neoplasms; facial nerve; otolaryngology
Tumors of the salivary glands comprise less than 4% of head and neck tumors.1 Most salivary gland tumors occur in the parotid gland with over 80% being benign.1,2 For benign parotid tumors, superficial parotidectomy is the standard approach to resection depending on their location within the gland. Surgical planning aides such as fine-needle aspiration (FNA) and imaging cannot always provide a definitive diagnosis for the malignant potential of a mass but remain a vital step in the workup of these masses. For this reason, surgeons should be prepared to convert to a total parotidectomy.3 Even for benign lesions, total resection of the mass is imperative as certain pathologies, such as benign mixed tissue tumors, can recur.4 A standardized approach to parotidectomy that preserves the opportunity to convert the procedure is an important skill for head and neck surgeons to develop.
Figure 1. Anatomy of the Facial Nerve in relation to Parotid Gland.Patrick J. Lynch, medical illustrator, CC BY 2.5 <https://creativecommons.org/licenses/by/2.5>, via Wikimedia Commons
A standardized approach to parotidectomy is particularly important to minimize risk to structures in the surgical field. The facial nerve is the primary critical structure enmeshed in the parotid gland. It serves as a critical landmark that artificially divides the superficial from the deep lobe of the parotid.2 Nerve stimulatory control units and nerve integrity monitoring systems provide intraoperative stimulation and monitoring. These tools assist with the identification of the facial nerve and confirmation of its integrity but should not replace a surgeon’s anatomic knowledge of surrounding landmarks. For this reason, the surgeon must confer with the anesthesiologist to ensure long-acting paralytic agents are not used. Methods and landmarks to identify the facial nerve intraoperatively include the tragal pointer, the tympanomastoid suture line, retrograde dissection, the tragal ‘pointer,’ and the digastric muscle.
A 39-year-old female presents with a mass on the left lateral side of her face that has grown noticeably over the past 2 years. The patient believed it was a small sebaceous cyst. However, as the mass continued to grow, she sought care from her family physician. She reported no other symptoms. She does not smoke. She does not have a history of cancer or radiation to her head and neck. Besides the mass, her history is unremarkable, and she does not take any daily medications. Her family physician referred her to otolaryngology due to the concerning location of the mass.
On exam, the patient had a 3.6x3-cm mass on her left lateral face. The mass is fixed and non-tender with no erythema. Cranial nerves II–XII are intact. She has no cervical lymphadenopathy. Aside from her primary lesion, the rest of her face and skull is symmetric.
An ultrasound of the lesion demonstrated a hypoechoic mass and a fine needle aspiration was consistent with pleomorphic adenoma but was not definitive. Therefore, additional imaging was recommended. I have never seen a case of FNA deferment due to concern of facial nerve damage.
A computed tomography scan demonstrated a homogeneously enhancing lesion measuring 3x2.5-cm overlying the left parotid gland. On magnetic resonance imaging, the mass appeared heterogenous on T1 series with hyperintensity on T2 series. The combination of imaging and pathologic findings was consistent with pleomorphic adenoma.
Pleomorphic adenomas, also known as benign mixed tumors, represent 84% of benign parotid masses.5 Approximately 75% of pleomorphic adenomas originate superficial to the facial nerve.6 Superficial tumors can progress to the level of the deep parotid lobe generating a dumbbell-shaped mass on imaging.
Pleomorphic adenomas originating from the deep lobe have unique characteristics compared to their superficial counterparts.7 (What are these unique characteristics? Why would this statement be added with a reference without including the specifics of the comment).
The treatment for pleomorphic adenomas is surgical resection with parotidectomy. It is important to maintain a clear margin of tissue without violating the capsule of the tumor to avoid recurrence or potential “seeding” of the mass with multiple areas of recurrence. A partial superficial parotidectomy may accomplish this goal depending on the size of the mass.3 If a tumor cannot be definitively excised from surrounding tissue, the surgeon should be prepared to convert to a total parotidectomy. Regardless of approach, the facial nerve should be carefully dissected and preserved unless tumor characteristics necessitate sacrifice of the nerve.
Postoperative radiation therapy has been explored for pleomorphic adenomas. Most examples of this practice involve patients with margin-positive resections, recurrent pleomorphic adenomas, or challenging tumors that are enmeshed with the facial nerve.8–10 The decision to pursue this treatment should be determined upon consultation with the patient, a radiation oncologist, and a head and neck surgeon to assess utility and necessity.
Recurrence rates of pleomorphic adenomas after parotidectomy range from 1–4% for superficial parotidectomy and below 1% for total parotidectomies. 11,12 Most recurrences occur within 18 months of resection. Therefore, appropriate and consistent follow-up particularly within the first 2 years post-resection is advised. Recurrent pleomorphic adenomas often appear as multiple small tumors found along the path of surgical excision and can be mistaken for adenopathy initially. The mechanism of the apparent tumor seeding is still under investigation with the working hypothesis being that residual tumor cells may be left behind and regrow or secondary to capsule violation. Interestingly, pleomorphic adenomas that originate from the deep lobe appear to not have as high as a risk for recurrence even when only enucleation is performed.7 It is vital that treatment for this tumor type removes all pathologic tissue with a perimeter of normal tissue to minimize recurrence.
Contraindications to parotidectomy alone include distant metastatic disease and tumor invasion of the parapharyngeal space, mandible, skin, or ear canal. These other situations may necessitate a combined approach with other surgical specialties. Metastatic pleomorphic adenoma, while rare, may be responsive to radiotherapy after resection of the primary tumor.10
Large pleomorphic adenomas that invade other compartments will require more extensive surgery than a standard parotidectomy.
With the starting incision, cosmesis and exposure are important to consider. By utilizing a “Gull-Wing” incision to mitigate tissue contraction and by hiding the incision in the hairline and skin creases, surgical scars can become imperceptible. However, the initial incision may have to be moved to a more visible area depending on the location of the mass.
As the tissue flap is raised at a level dependent on the level of the mass, important landmarks include the external jugular vein and great auricular nerve. Identification of these landmarks allows for preservation of the nerve as long as no tumor encroaches upon it. This can achieve preservation of sensation to the inferior aspect of the ear. With the nerve identified, the parotid fascia can be dissected from the perichondrium of the external auditory cartilaginous canal. This allows continued exposure of the tragal pointer, which is vital for identification of the facial nerve as the nerve courses 1 cm anterior and inferior to the tragal pointer in normal anatomy.
The digastric muscle is the next important landmark, which helps identify the common facial vein anteriorly and also demarcates the level of the facial nerve in the parotid. Finally, the tympanomastoid suture can be palpated, which if followed to the styloid process would transect the facial nerve. The authors prefer to identify this structure but not use it as a dissection plane due to its depth. Instead, after identifying the three key structures, the parotid fascia can be cut superficially and bluntly dissected from the posterior belly of the digastric muscle to the anticipated location of the facial nerve. Care should be taken to avoid the transverse facial artery which exists in the same plane. Once the facial nerve is identified at its main trunk, the upper division of the facial nerve can be dissected (the primary branch point of the facial nerve into superior and inferior divisions is referred to as the ‘pes anserinus’). This is challenging due to the superficial temporal vessels, so it is advised to dissect along the superior portion of the facial nerve rather than on its lateral surface. Attention is then turned to the lower division. Identification of the retromandibular vein and posterior facial vein can aid in identifying the expected course of the marginal mandibular branch as this nerve lies superficial to the veins.
After completing superficial dissection, the deep lobe can be dissected. The facial nerve should be mobilized off all the soft tissue in this region. Superficial temporal vessels should be controlled at this point. The deep compartment can be identified by locating the terminal branch of the external carotid artery and the posterior facial and retromandibular veins. The space deep to the facial nerve in this region is safe from damaging the facial nerve and allows for access to deep lobe tumors. The deep parotid can be separated from the posterior border of the mandible down to the styloid process. Deep vessels to control here include the internal maxillary artery and vein allowing the surgeon to free the deep lobe from the styloid process and parapharyngeal fat thus completing the dissection.
The presented dissection and accompanying case highlight important principles in parotidectomy. The standard approach presents possible variations in dissection based on tumor location. It allows for the conversion of the procedure to total parotidectomy. Finally, it provides systematic assistance to identify important landmarks and safely locate the facial nerve.
Regarding the case, treatment for pleomorphic adenomas has improved as evidenced by the decrease in recurrence. As mentioned, current rates of recurrence are consistently less than 4%; however, historically the recurrence rate was 20–45% when only enucleation was performed.6,11 The adoption of parotidectomies is credited for this accomplishment.
Superficial parotidectomy lasts approximately 2 hours. Minimal blood loss is anticipated during the procedure ranging from 40–60 cc. The head of the bed can be elevated to minimize bleeding.13 The modified Blair incision is most used. For ideal cosmesis, the incision should follow the natural creases of the neck depending on the need for neck dissection or be placed along the hairline particularly in individuals with long hair.14
Closure of the wound should include placement of a surgical drain. Drains can be removed when output is 10 ml or less per day. These drains can be removed on an outpatient basis if the drain output goal is not reached during hospitalization. In relatively small parotid tumors, these drains are often removed in the morning or afternoon on the day after surgery (postoperative day 1).
Important complications include facial nerve paralysis and/or permanent facial nerve damage. If intraoperatively the nerve is confirmed intact, but the patient still experiences weak neuromuscular responses to stimulation, it is likely they will make a full recovery.2 Mild neuropraxia should resolve in 4–6 weeks but may require longer depending on traction placed on the nerve during surgery. Consultation with physical therapy for facial nerve rehabilitation may be beneficial in such patients.
Other possible complications include Frey syndrome, salivary fistula, facial asymmetry, first bite syndrome, and other standard surgical risks such as bleeding, infection, and complications of anesthesia.
Most patients can be discharged within 24–72 hours after the procedure. Patients return to the clinic in 1 week to discuss results from pathology, establish follow-up timeline, and have sutures removed if non dissolvable sutures were used. Additionally, patients are advised to avoid acidic foods for 6–8 weeks after surgery to allow the parotid gland to recover.3 There is no clear consensus on when to perform surveillance imaging for recurrence. Often, biannual physical exams alone are sufficient to detect new masses suggestive of recurrence. Long-term relationships develop between surgeons and their patients as recurrence can occur 10 years or more after resection.
Standard special equipment utilized for this surgery13:
Jackson-Pratt bulb suction drain or TLS drain
Nerve stimulator control unit and instrument (Parsons McCabe)
Nerve integrity monitoring system (NIMS)
C. Scott Brown also works as the lead editor of the Otolaryngology section of the Journal of Medical Insight.
This case is a standard parotid dissection demonstrated on a cadaver; no consent was required. All other persons seen in the video consented to publication of the media.
- Jennifer R. Wang, Diana M. Bell, Ehab Y. Hanna. Chapter 84: Benign Neoplasms of the Salivary Glands. In: Flint PW, Haughey BH, Lund VJ, et al., eds. Cummings Otolaryngology-Head and Neck Surgery. 7th ed. Elsevier; 2020:1171-1188.
- Galati L. Chapter 92: Superficial Parotidectomy. In: Myers EN, Snyderman CH, eds. Operative Otolaryngology-Head and Neck Surgery. Third edition. Elsevier; 2018:613-617.
- Ashok R. Shaha. Chapter 3: Superficial Parotidectomy. In: Khatri VP, ed. Atlas of Advanced Operative Surgery. ; 2013:23-28.
- Patey DH, Thackray AC. The treatment of parotid tumours in the light of a pathological study of parotidectomy material. Br J Surg. 1958;45(193):477-487. doi:10.1002/bjs.18004519314
- Spiro RH. Salivary neoplasms: overview of a 35-year experience with 2,807 patients. Head Neck Surg. 1986;8(3):177-184. doi:10.1002/hed.2890080309
- Rosai J, Ackerman LV. Chapter 12: Salivary Gland. In: Rosai and Ackerman’s Surgical Pathology. 10. ed. Expert consult. Elsevier, Mosby; 2011.
- Harney MS, Murphy C, Hone S, Toner M, Timon CV. A histological comparison of deep and superficial lobe pleomorphic adenomas of the parotid gland. Head Neck. 2003;25(8):649-653. doi:10.1002/hed.10281
- Chen AM, Garcia J, Bucci MK, Quivey JM, Eisele DW. Recurrent pleomorphic adenoma of the parotid gland: Long-term outcome of patients treated with radiation therapy. International Journal of Radiation Oncology*Biology*Physics. 2006;66(4):1031-1035. doi:10.1016/j.ijrobp.2006.06.036
- Armitstead PR, Smiddy FG, Frank HG. Simple enucleation and radiotherapy in the treatment of the pleomorphic salivary adenoma of the parotid gland. Br J Surg. 1979;66(10):716-717. doi:10.1002/bjs.1800661012
- Patel S, Mourad WF, Wang C, et al. Postoperative radiation therapy for parotid pleomorphic adenoma with close or positive margins: treatment outcomes and toxicities. Anticancer Res. 2014;34(8):4247-4251. PMID: 25075054
- Laccourreye H, Laccourreye O, Cauchois R, Jouffre V, Ménard M, Brasnu D. Total conservative parotidectomy for primary benign pleomorphic adenoma of the parotid gland: a 25-year experience with 229 patients. Laryngoscope. 1994;104(12):1487-1494. doi:10.1288/00005537-199412000-00011
- Witt RL, Eisele DW, Morton RP, Nicolai P, Poorten VV, Zbären P. Etiology and management of recurrent parotid pleomorphic adenoma. Laryngoscope. 2015;125(4):888-893. doi:10.1002/lary.24964
- Parotidectomy with Facial Nerve Dissection. Iowa Head and Neck Protocols. Published April 29, 2020. Accessed January 27, 2021. https://medicine.uiowa.edu/iowaprotocols/parotidectomy-facial-nerve-dissection
- Zhang J, Jiang Q, Na S, Pan S, Cao Z, Qiu J. Minimal Scar Dissection for Partial Parotidectomy via a Modified Cosmetic Incision and an Advanced Wound Closure Method. Journal of Oral and Maxillofacial Surgery. 2019;77(6):1317.e1-1317.e9. doi:10.1016/j.joms.2019.02.036
- Malignant Tumor
- Benign Tumor
- Raising the Flap
- Dissect Great Auricular Nerve
- Dissect Above Band of Dense Connective Tissue
- Identification of Tragal Pointer
- Expose Tragal Pointer
- Identify Digastric Tendon
- Cut Through Parotid Fascia
- Identify Artery
- Identify Facial Nerve
- Dissect Superficially Along Facial Nerve
- Follow Superficial Temporal Vessels
- Identify Lower Division
- Deep Lobe
- Mobilize the Nerve
- Control Superficial Temporal Vessels
- Find Terminal Branch of External Carotid
- Dissect Parotid from Posterior Border of Mandible
- Free Deep Lobe from the Styloid
The first thing to think about is your incision. You basically have four things to think about. One is cosmesis. You can do an incision in a crease here. I try to do a little “gull-wing” - just you want to have a straight line that shortens. And then around the - the ear, I like to make a point, so as that contracts, you don't get pulling up of the ear like that. Now if you really want to hide the incision, you can do it as a facelift, which you can go way back here and into the hairline and then elevate a real broad flap like that - shave the hair a little bit. That's - this works if you have a posterior lesion here. Tumor’s up there. Your exposure’s going to be a little bit worse, but it's a nice way to do it, particularly in women who have - wear their hair long; you can shave a little hair and the - the scar is basically imperceptible. The other option is taking it down into a crease like this, and the - the decision of how far to go depends on whether or not you're going to incorporate a neck dissection. So if you’re going to do a neck, you may want to take it down in here. If you’re going to do a parotid, you can even just limit the incision in a crease. You’re pretty limited there. So that's the first thing.
The next thing is your plane of dissection and raising your flap. If you - if your tumor is - so you got to point here - if your tumor is on this - is on the capsule or near the capsule of the gland and it's malignant, I like to raise the fat, the plane, above this mass. So if you do that, you're going to want to see the bottom of the hair follicles in your flap. If it's benign and the tumor’s deep in the gland, I prefer to save this mass. I don't know whether that helps with the postoperative Frey’s or anything like that, but it also gives you a little bit of thickness.
The - the other topographical anatomies you got to be aware of are the great auricular nerve. It runs behind the EJ and about halfway between the mastoid tip and angle of the mandible. If - if you can and you don't have a tail or parotid lesion, you can dissect the nerve up and save the posterior branch, which will preserve some sensation. If you just dissect it all the way up, you're going to leave a little bit - you’re going to leave a little bit of parotid here as you preserve the nerve, but that's okay as long as the tumor’s not nearby.
The hardest place in elevating this flap is right here because there's a - there’s a dense connective tissue band there that - that you don’t really - you can't see the plane, but the - the key is - is just to stay on top of it. I think I’m beneath - this is that connected tissue band here. You can barely see it, but I think I'm on top of the - this mass here - below this mass here. Okay so - so there’s fat, and I’m deep to mass. Okay, then you can take it right to the front end of the gland. Just want to raise this back a little bit - just so you can identify the EJ, and - and this is going to get you your exposure. There.
So the next move is to separate the parotid fascia from the perichondrium of the external auditory cartil - the cartilaginous canal, and when you dissect, that's a - usually - a very easy plane to get into. It's a - it's a kind of a wispy plane, and if you're in it, it will spread pretty easily. You can see that there is a plane here.
Okay. So now you want to just expose it to the level of the tragal pointer. Okay, that's your first landmark. Your three landmarks are your tragal pointer - you see that nice areolar plane there? That's where you want to be, okay? So there’s your tragus right there, and just cut down through there, Kevin. Let’s see - you don’t want to get too deep. Okay, so you got to expose that whole tragal pointer, which is - you can see it there. It comes into a point, okay? That's the tip of it. So the - the location of the facial nerve is 1 cm anterior and inferior to the tragal pointer unless there's a tumor pushing it up from below - a deep lobe tumor - or it’s being distorted by the tumor. That’s usually where it is. The key is there - it is in the parotid gland, okay?
So to get there, you've got to cut the fascia of the parotid. The other way to do it is to follow the tympanomastoid suture line that - in the books, they say that is the most consistent landmark that you can follow - the tympanomastoid suture line down into the stylomastoid foramen. I don't like to do that personally because I just feel like it's too deep. The nerve is going to cross the parotid fascia, so you won't even have to get into the parotid. You can just dig down there and get to it, but it’s a - tends to be a deep hole down there. So I - that's - I - I don't know who does it - if the other - my esteemed colleagues do it that way, but I don't like to do it unless forced.
So the next point here is you got to find the - the digastric tendon, right? So this looks like a CM to me and some wonderful tissue planes. That's probably EJ there - going to cut it. So you got to elevate this off. There's digastric there, okay? Then you can just follow this digastric, and there’s only one thing that crosses the digastric, which is the common facial vein, anteriorly. And once you got the digastric, you can now do this dissection here very easily until you get all of this removed. Okay. And when you get to level of the digastric and the tragal pointer, which is here, you can feel the tympanomastoid suture, which is right there. Okay, then what you have to do is - now you know that the nerve is going to be about here, right? About a centimeter anterior inferior - and it's going to be at the level of the digastric in the parotid.
So the next move here is actually to go through the parotid fascia and just make sure that you can see everything, and I'll probably cut the nerve here but… Okay, so this just - oh see I just - did you see that fascia I just cut? It's all parotid fascia that's going to... Okay. So, it should be about right here, and all this is fascia, which you cut. Now there’s usually an artery that lives above that. I'm - I’m not sure what that artery is called. Does anyone know the name of it? I think it's right there. And that'll be a bother. It's always there. Okay. And that should - this should take you right to the nerve. I don't know if that's it or not. Okay, it’s either that, or it’s the artery.
So there's a structure here. In the cadaver, it's hard to tell whether it’s her artery or nerve, but - see that? It's kind of right where it should be. You can follow it forward a little bit to see if it is it. Okay. Looks like that's it. Okay, so that's probably the facial nerve there. Is there anything below there? No. Here’s the artery above it, okay? So this is probably lower division here. The pes, yeah.
So now, the tendency here is - is to just - once you see that, is to start cutting everything above it, but remember - it's a lateral dissection, so you want to make all your cuts inferiorly or superiorly. I've had most trouble with superior with the upper division and that forehead branch. That's hard because you have all these superficial temporal vessels that usually are deep to it, but there are - sometimes, there’s branches above it, so the best thing to do is instead of - I try to - tend to follow the superior most aspect. If this is your nerve, instead of dissecting this way - it's going up - I try to stay on that side of it - that way, so I can see it going superiorly, okay?
You can open all that up. Let’s see. I think the branch is going this way. You can see your - your superficial temporal vessels there, and then you would follow it the other way also.
So I’m going to take that. So there's the lower division there. You can see it right there. See, I'm just taking everything. So the other thing to remember is - and this is important - is that the lower division - particularly the marginal mandibular nerve - its relationship to the retromandibular vein and the posterior facial vein; it's always superficial to it, okay? So you - you got to look for that, and that - that nerve will go over the top, and you can see - I think this is - this is a vein here, and the nerves are going deep to this. You got to actually follow those nerves. Those ves - those nerves then divide these vessels above it. Okay. Let me just take it here. Hope I don't cut it here. Let’s see. So there's - this is probably platysma branch going down. This is probably the marginal branch going up, okay?
So then when you get to this point, I’m just going to do this for expediency's sake. I'm going to take all of these. There’s a big vessel there. I'm just going to go ahead and take this, okay? Because I want to get to the deep lobe. The dissection of the peripheral branches is pretty straightforward. So now - if you hold that out - the deep lobe anatomy is important, and you know, as I told Helen the other day, is whenever you're doing a parotid, you need to be prepared to do a total, okay? Depending on the pathology.
So, the first thing you do is you basically mobilize - mobilize the nerve, okay? Off. Just mobilize the nerve off all the soft tissue.
Then, you've got to control the superficial temporal vessels up here. You got to find the terminal branch of external carotid. It's best to find it low. I think it comes between - it's right here. Okay now, the - the point here is that the terminal branch of external carotid and the posterior facial - the retromandibular vein, again, go deep to the nerve. So, if you're doing a deep low parotid tumor or a parapharyngeal space tumor, you don't have to identify the facial nerve if you’re deep to those structures, okay? It's safe, but - and that's - that’s one way to look at it - superficial versus deep lobe - because deep lobe tumors are going to be deep to those vessels.
So you can dissect it out. You just got to follow all of the - and just detach all of the parotid from the posterior border of the mandible, here, and... There's the stylomandibular ligament and all of that stuff, but your deep - your deep part of your resection is your styloid, which is here, okay? And as you come across the front, the vessels you often forget about are the internal maxillary artery and vein, so you've got to find those, control them, take the artery here above and below, take the IMA, and then you can free up all the deep lobe off the styloid until you get to the parapharyngeal fat - and you just slide it under your nerves, okay?