KATIE VAN ABEL: Hello. My name is Katie Van Abel. I'm a head and neck surgeon at Mayo Clinic in Rochester, Minnesota. Today we're going to talk about transcervical approaches for parapharyngeal space, pleomorphic adenoma. We'll focus today on the surgical approach for these tumors. But for more information about the workup and the characteristics, please see Dr. Moore's excellent EMT in a Nutshell podcast on this topic.

Here we have a patient who presented to me in her mid-20s, who had undergone workup for headache, and had incidentally been noted to have a parapharyngeal space mass. As you can see, this is bright, both on T1 and T2. And you can see it is deep to the mandible and the parapharyngeal space.

When we went to the operating room, we positioned her supine on the table with a 4-lead facial nerve monitor in place. I like to use a nasal endotracheal tube to ensure that I have adequate access to her parapharyngeal space by allowing her teeth to completely close. We start by looking at her superficial anatomy, marking out the angle of the mandible and our planned incision.

We want to be prepared for all the possibilities in the operation, which includes the potential need to do a formal parotidectomy and facial nerve dissection. However, my approach typically will focus on the transcervical incision. So we mark that out inferiorly. I like to mark out where the external jugular vein goes, so that we can try and avoid injuring it with the injection.

I inject 1% lidocaine with 1 to 100,000 epinephrine as my vasoconstrictor. Then we paint and prep with our iodine prep. I think it's important to pay attention to your draping. We want to be able to ensure that we have access to a clear view of the face to monitor for facial twitching, but we also want to be able to have some mobility of the head so that we can turn it side-to-side if and when we need better access.

Next, I like to place inter-maxillary fixation screws so that we can actually pull the mandible forward to create the maximum amount of space for access to the parapharyngeal space. This is relatively well-tolerated, ensuring that we place it in between the dental roots, and well away from the mental nerve, placing the maxillary screw anterior to the mandibular screw, trying to measure, to estimate the maximum amount of forward protrusion of the mandible.

We used our standard MMF wires. This can be 16 or 18 gauge. You can see that as we set this down, we're pulling the mandible forward. You would do this just as you would for any mandibular trauma, or mid-face trauma, sitting the wire down tightly, and then trying to fold that in a candy cane fashion to avoid any inadvertent injury to your assistants, or to the patient's oral cavity.

Next, I like to use Tegaderm to cover the mouth and nose to ensure that we have a sterile field. We'll change our gloves, and then proceed to the parapharyngeal approach. We begin by making an incision with a 15 blade through the skin, the subcutaneous tissue, and then through the platysma, more anteriorly. Just posterior to the platysma, you'll typically find your external jugular vein, and your great auricular nerve.

So it's often safest to start forward towards the platysma. Next, we'll start raising our subplatysmal flaps. You can see here that it's really critical that we have excellent retraction, both vertically with our double-pronged skin hooks, as well as posteriorly, to tense the skin up. We'll work our way forward, ensuring that we have raised flaps all the way up over the mandible.

And then I will secure these with fishhooks, which we use here in Minnesota not only for fishing, but for retracting the skin. Here we're showing a nice view of the great auricular nerve, the external jugular vein, sternocleidomastoid muscle. And you can just make out the submandibular gland underneath the fascia. First, I like to define the inferior border of the submandibular gland. We can do this by raising the fascia just inferior to it. And this helps protect the marginal mandibular nerve, which will be in a position higher than this point of dissection.

This will allow us to start identifying both our common facial vein, if it's present, as well as our posterior belly of the digastric, which will be an important landmark for this operation. In this situation, or in this case, the external jugular vein and the great auricular nerve posterior enough that I felt that I could preserve them without limiting my ability to access the parapharyngeal space using a retractor. If this were to inhibit my ability to access the surgical site, I certainly would ligate the external jugular vein.

Next, we're going down to identify the posterior belly of the digastric. We do this by elevating fascia, and moving through with bipolar cautery in sharp dissection. It's important to remember that the posterior belly of the digastric does not always sit inferior to the submandibular gland, but in fact sits posterior to about the mid portion of the body of the gland. And this can be helpful when performing your dissection and looking for this muscle.

This patient was particularly thin, and had excellent anatomy. So we can see our digastric coming out towards us very nicely here. As we're dissecting, we can clearly see the posterior border of the submandibular gland. And then lying on top of our digastric muscle, the stylohyoid musculature. This is going to be an important landmark for us as we move superior to it, and look for external carotid artery.

So here, we're pointing out the posterior belly of the digastric muscle, the stylohyoid muscle. And as I pull the stylohyoid inferiorally, just superior to this, you're going to see the external carotid artery come into view. Now, this is a very reliable landmark, and it's a really nice, safe way to find the external carotid if you're doing a total carotidectomy, or a parapharyngeal dissection.

Now, this is a high-flow artery. It's important that we have really good clamps on this artery. So this is going to be tied with a surgeon's knot. Now, there is risk for First Bite Syndrome by interrupting the sympathetics that travel along the adventitia of the external carotid artery by making this maneuver. However, safe and adequate access to the pharyngeal space will be limited if you do not appropriately ligate the external carotid artery as you access this space.

As we move deeper in our direction, we need to move the posterior belly of digastric and the stylohyoid muscle inferiorally, and retracted out of the way. This is opening the space between the mandible and the posterior belly of the digastric, which is aided by the fact that we have a nasotracheal tube, and we have our IMF screws in place. The next thing we need to do is move through our stylomandibular ligament. As the name suggests, this ligament spans between the styloid process and the mandible.

It's something that's often felt more than it is seen. Fortunately in this case, we had a really nice demonstration of this ligament. It's more of a fascial condensation. So you can see here that it's working a little bit harder to try and get through that tissue. And it really is our access point to finally open up our parapharyngeal space.

All right. So once we've divided that, you can see that with a simple finger sweep, we can really start opening things up. As I pull in inferiorally, you can start to see some of the other styloid musculature come into view. This is our styloglossus muscle. Recall that I mentioned that the stylohyoid and styloglossus are separated by the external carotid artery. You could just make out there the tip of the styloid process.

As we start working our way above the styloid process here, you can see our parapharyngeal space mass presenting to us through our parapharyngeal space. I'm going to use blunt dissection. We'll start with a Kittner. You can see that I'm constantly using my forceps in a closed fashion here, so as not to disrupt the capsule of the tumor. We're working over the top of the styloid process there, trying to free up any attachments circumferentially around this tumor. One of the key maneuvers, when we're doing a parapharyngeal space dissection, is blunt finger dissection.

Now, it's important to keep in mind where your styloid process is, because what you want to avoid is accidentally puncturing your tumor against your styloid process. So one move that you can do is to fracture the styloid process inferiorally. You have to take some care to prevent a superiorally-placed fracture line on the styloid process from puncturing your tumor.

I work my way all the way around the tumor, feeling for familiar landmarks, like our skull-based landmarks, such as this spine of the sphenoid, and palpating intermittently for our vasculature. As I start to work towards the pedicle of the tumor on the deep lobe of the parotid, we can again start working with our Kittner, trying to identify where that tumor is actually attached to the gland. I go back and forth between finger dissection, ensuring that I have everything nicely and circumferentially freed up, and using the Kittner.

And now here, I feel with my finger that I'm really freed up, with the exception of my pedicle. So before I just pull that out, I want to ensure that I ligate this with a cuff of normal parotid tissue. We recall that there is a risk for recurrence if we do not take a cuff of normal parotid tissue. And in this setting, it's typically this pedicle of tumor against the [INAUDIBLE] parotid gland. I typically take this with a clamp. We can bipolar cauterize the intervening parotid tissue, and then I'll ligate the remaining parotid tissue.

At our institution, we're able to send this for frozen section pathology. And this confirmed our suspicion of a pleomorphic adenoma. It was completely excised, and so this was the end of our operation. No further dissection was needed. However, if this came back as a malignant tumor, we would need to consider moving on to a total parotidectomy and upper neck dissection for oncologic management, depending on the grade of the tumor.

Now we can look at our anatomy. Deep within the wound, we can see the superior pharyngeal constrictor. We can see our styloglossus, stylohyoid, and our digastric muscle. This is a nice demonstration of the anatomy here. I like to place a drain. We created quite a dead space in this wound. So placing something relatively small like, a 7 flat channel drain up into this defect, I think, helps to prevent fluid accumulation.

I then close this in a layered fashion using [INAUDIBLE] vicral for [INAUDIBLE], closing our platysma together, and re-approximating the soft tissue in a tension-free fashion. Once this is complete, we can use Dermabond to close our skin. Next, we'll remove our IMF screws using just an empty screwdriver and cutting out our wires.

And this will bring us to the termination of our procedure. The key points for this operation are access. So everything we can do to optimize our access will help us be successful in removing these tumors. So this includes nasotracheal intubation, doing something to help move our mandible forward. I like using IMF screws, because I can avoid putting a retractor on the marginal mandibular nerve to pull my mandible forward.

We need to remember our steps, which include elevating our subplatysmal flaps, moving inferior to our submandibular gland, identifying the possibility of the digastric. This will be pulled inferiorally, as we work over the top of the stylohyoid and digastric muscles, to access our external carotid artery. We move through this stylomandibular ligament to identify our tumor. Then we use blunt dissection, taking care to avoid injuring the tumor on sharp structures, such as our styloid process.