 We hope you enjoyed that replay of Dr. McCurgy's talk on head and neck spaces. Dr. McCurgy is here live to take your questions, so we'll open the floor for any questions you may have. You can submit a question through the Q&A feature, and we will try to get to as many as we can before our time is up. Dr. McCurgy, welcome. Thanks for being here. Hey, thanks a lot. Thanks for having me. How much time do we have for the Q&A? You can go 10 minutes, 15 minutes, however you feel. Okay, sounds great. Hello. Thanks again for having me. Let's see. We have a couple of questions in the question and answer again. Thanks so much for attending. We had lots of registrations and a lot of people attend, so it's fabulous. So the first question I have are, what are the keys to consider to differentiate cordomas from condo sarcomas? So I saw that in the chat and what I'll do is I'll go ahead and bring this lecture up and hopefully, is that Ashley on the screen? I don't know who's on there. Is that you or who's on the screen? Yes, I'm here. So I'll just, I just wanted to, you can see my screen. Is that right? Yep, we sure can. Okay, great. So it's a great question and I see a lot of questions popping up. So I'll try to get through these as quick as I can. So the thing about, I'll just go this way is probably easier. You know, cordomas are malignant tumors that arise from the notochordal remnants and it's always been confusing to me because when I hear notochord, I actually think of the spinal cord. But in actuality, the notochord is the precursor to the spine itself. So it goes all the way up from the clivus and the basisvenoid all the way down to the tip of the sacrum. So as a result, if you don't think of cordoma as the core and you just remember cordoma as the area where the spine develops, that really is one of the key features that helps me, meaning that cordoma is actually arise from the embryology, embryological determinants of the notochord. So as a result, when we do look at cordomas, cordomas tend to be midline lesions because they arise from the spinal cord. And they also tend to have this pseudo, if you will, I always call it this sort of a pseudo cystic appearance. And that's because they create fissiliferous cells. So they tend to be cystic on T2, which they're really not because they contain a lot of mucin and they also enhance with contrast. So they are solid, but they tend to be midline. Another example here, you look at this and you think it's cystic, but in actuality, when you end up giving T1 weighted images with contrast, you can see that it's enhancing. So they're midline lesions. Now, if I fast forward to the chondrosarcoma, chondrosarcoma arise pyramid line, and they tend to arise from this area just to the left of midline, which is the petroclival synchondrosis. So cordomas tend to be a little bit more pyramid line, and they also oftentimes will have what my musculoskeletal folks refer to as rings and circles. And they tend not to have that, if you will, that pseudo cystic appearance. On T2, they can either be low signal, they can be high signal, and that T2 signal really depends on the actual elements. But as a rule of thumb, cordomas tend to be more pyramid line as opposed to midline. And they have this, if you will, new bone formation. So the next question that I got, well, we have so many right now. I'll try to get these quick as I can is, how do you differentiate between pleomorphic adenomas and worthens tumors? So let me try to exit out of this one. There we go, and I'll try to share a different screen because I saw that pop up when I was looking at this. And this actually goes back to the lecture that you just saw. So this is what helps me differentiate pleomorphic adenomas from worthens tumors. And literally this just came up yesterday in the tumor board that I attend. So worthens tumors, the other name, if you remember this, I think this kind of helps you. The name for worthens, other name for worthens tumors is called cyst adenoma lymphomatosum. And what that means is the lymphomatosum means that it actually arises from lymphoid tissue. And in the parotid gland, they're actually inter-parotid lymph nodes and they arise in four levels. They arise anterior to the traga, so it's pre-tragal, below the parotid capsule. So they're subcapsular, along the facial nerve, and then also in the tail of the parotid gland. So they're four different areas. So lymph nodes tend to be multiple. They tend to be bilateral and they have a propensity for the parotid tail. So because worthens tumors arise from that lymphoid tissues, if I see something that's arising in the parotid tail or something that's multiple, then I start thinking about worthens tumors. Now, on the other hand, if I see something that is high signal on T2 and in general tends to arise from the body of the parotid gland, tends to be unilateral and it basically stays away from the tail of the parotid gland. Then I think of pleomorphic adenomas. So sometimes it can be hard for sure, but to answer your question specifically, is something's high signal on T1, excuse me, high signal on T2 that's solid and that sort of arises in the main portion of the parotid gland, I start thinking about pleomorphic adenomas. But on the other hand, if I see something that is multiple, bilateral, and especially involves a parotid tail, then that really tends to favor worthens tumors. So the next question that came up was, you mentioned that pleomorphic adenomas are the most common tumors of the paraphera and glial space. What glandular structure do they originate from? And that's a really great question. And the way that I think of this is as follows. The most the head and neck structures that form the regular fibro fatty area and the muscles are pretty ubiquitous. They occur anywhere in the body. Now there are certain areas in the head and neck that arise to what I would refer to as the head and neck is tumors and specifically salivary gland lesions. So the reason why pleomorphic adenomas are the most common tumors of the paraphera and glial space is that during embryology, you can have these small little rests of minor salivary gland tumors that tend to embed themselves in the paraphera and glial space. And as a result, when you have those little areas of ectopic salivary gland tissues, this is what gives rise to things like pleomorphic adenomas or occasionally you'll see adenoid cystic carcinomas, etc. But in general, pleomorphic adenomas are the most common tumors that arise from these ectopic rests. And because these ectopic rests are located in the paraphera and glial space, this is what gives rise to pleomorphic adenomas. So the next question that I had was how do we differentiate necrotic retro phera and glial lymph nodes from abscesses? So let me go ahead and stop my share because I saw this one too while the talk was going on. And let's see here. Help me out here. How do I stop my share? Let's see. Oops. Sorry about that. Maybe at the top of your screen. There we go. Yeah, sometimes it gets lost there. Yeah. Thank you. So we'll go to this next one. And I think I pulled that one up. Again, another great question that was pertinent to this talk. So we'll start with this. Can you see my screen? Is that a yes? That's perfect. So when we started looking at the head and neck structures, we already talked about the visceral space. So I think the way I said, if you say I, anything that you look in your mouth is in the visceral space, then we talked about this fascia layer. And this fascia layer has different names to it. You can either call it the visceral fascia or the fringomucosal fascia or the buccal, or the fringofringle basara fascia. There's so many names to it. In fact, the names have been changing for the last 250 years. And I assume in the next 20 years, there may be another name. I mean, who knows? But the important thing to know is that there is this fascia layer that separates the visceral space from the spaces behind the pharynx. And where these little green dots are, those are the retroferential lymph nodes. So what happens when you have an infection involving the tonsils? And the pharynx, the primary drainage ends up going to the medial and the lateral retroferential lymph node, and they have a propensity for the lateral retroferential lymph nodes. So the first area of infection are going to be the deposition here, this pus involving the retroferential lymph nodes. And this is what we refer to appropriately as suppurative adenitis. This is not an abscess, but it is supuration or pus within the retroferential lymph nodes. Then as they grow, I always think of them as water balloons. So as it gets bigger and bigger and bigger, the water balloons pop and then all of a sudden you end up getting pus in the retroferential space. So this is a true retroferential space abscess. Now, when you have a retroferential space abscess, if it gets worse and worse and worse, it can grow posteriorly and eventually erode into the top of the spine. So this and specifically at C1 and C2. So here we have this retroferential space abscess extending posteriorly to involve the spine. And if you look closely, it's actually extending into the epidural space. And then when you could give contrast, you can see this epidural space abscess. So here when you give contrast, you can see the fluid collection in the retroferential space. Then you have this erosion of the spine and then you have the epidural collection in the anterior spinal canal. So that's the difference between suppurative adenitis in retroferential space abscess. And that is the normal, if you will, pathophysiology and spread patterns of the retroferential space infections. So the next question, wow, we have a lot. Keep them coming in. So the next question that I have is what is your experience with Delphian lymph adenopathy in children? And the bottom line is it's not very common. Most of the Delphian lymph nodes, so when we mean Delphian lymph nodes, what these Delphian lymph nodes are, is that they are the pretracheal lymph nodes. So they're technically a level six lymph nodes and they're located anterior to the trachea. And I haven't had much experience of these in children. The few times that I have seen it has probably been in patients with tuberculosis. In the old days, we would call tuberculosis of the neck. The term that we used to use was scrawfula. So I think in occasionally, I assume these tuberculosis of the neck, the scrawfula could involve the expected location of the Delphian lymph nodes, but in general, not much experience in kids. Most commonly, I see them in adults and they are usually due to recurrences in head and neck cancer. Specifically, I've seen it in swamous cell carcinoma and in thyroid carcinoma. And it's not the initial recurrence. Oftentimes, it's patients that have been treated with head and neck cancers with squamous cell carcinomas with multiple treatments. And eventually, the Delphian lymph nodes end up getting involved oftentimes because they're not involved in standard neck dissections and the radiation therapist may not particularly focus on the pretracheal lymph nodes during treatment. So the next question was the differentiate between rector, pharyngeal, space, abscess and cellulitis. So let me bring that, Ashley, we do an okay with time or what? Absolutely. You go as long as you'd like to. Okay. If you've got another, you've got to be somewhere else. Let me know. So again, another, another great question. And so let me, let me bring this up and let's see here. Yeah. So I think this is probably the best example here. So can you see my screen, Ashley? Yes. Okay. Great. So that, that it's really isn't an excellent question. And this is an example of edema or sometimes we use the term retrofaryngeal space diffusion. So this is oftentimes associated with CPPT disease involving the dens and we call this calcific tendinitis. And so edema involved in the retrofaryngeal space, it tends not to have as much mass effect. You can't have some mass effect, but not a lot, but it tends to be, you know, it's kind of fuzzy and hazy and very, very symmetric. And with the leap of faith, this word by arrow is pointing at right now actually identifies the alar fascia. So the alar fascia is not always seen, but if I see this low attenuation here and I see the alar fascia, then that really makes me 100% sure that I'm dealing with edema. Now, on the other hand, when we start looking at retrofaryngeal space abscesses and I'll show a more classical example. Here we can see there's fluid, there's midline and it has much more mass effects. So there really is a definable collection here. Whereas before when we talk about retrofaryngeal space edema, it's not as well defined. It's a little bit more symmetric and it's a little bit more separated. Now, if you don't see a lot of head and neck and you see something like this and you're not sure, my feeling it's always better to err on being more conservative and suggesting the possibility of an abscess as opposed to not and then being wrong and it is because that can lead to more problems. But so if you're not sure, then it's probably better to just at least raising the possibility because what you don't want to do is that you don't want to say that something is not an abscess and it turns out that it actually is an abscess. So that's where I would sort of titrate if you will or set my reasset. Let's see. So that was the ones that I saw before. Now what I see here is if you evaluate subglottic symptoms, do you have them scanned and with expiration saying E to evaluate the trachea? So again, a terrific question in general. I don't. I think when you are evaluating patients with subglottic stenosis, the main thing is there is there an anatomic narrowing in the region of the subglottis and I think that can be evaluated just with standard imaging. You know, I think I mentioned before, I actually see patients every week. In fact, Wednesdays is the days I see patients in in our head, neck clinic. And so I'm actually in there when they perform the endoscopies and the laryngoscopies. And so I can actually see the ease and the reversed ease and the effect that it actually has on the vocal cord. And I know oftentimes we will say this in radiology should we do these vocal cord procedures. But in general, I don't think they're necessarily very helpful because, you know, when the surgeons do perform an endoscopy, they can they can actually see the vocal cords move. So from my standpoint, at least my opinion is, is that you can do this if you want to, but in general, you know, what we are looking for is an anatomic cause of the subglottic stenosis. And I don't not sure how much the vocal cord manipulations will help with that. The next question is, how do we differentiate a glandular lesion from intraglandular lymph adenopathy? I have to admit, I'm not sure what that means. Maybe if you could provide a little bit more detail, I can, I can answer that. But I don't want to give a tangential answer. So if Dr. Pritthas Dalon, you can just maybe type that question again. The next question is the infertemporal fossa versus the retro maxillary space. So let me bring up the spaces talk here. There's the spaces of that neck talk. Let's see. Whoops, hold on for a second. I didn't do my share. Sorry about that. Spaces, there we go. Okay, so in general, the way to think about it is let's say you should be seeing the screen. Can you see it, Ashley? I can see it. Yep. Great. Okay. So again, in the head and neck, what we end up doing is that we give different pieces. Sorry about that. Different pieces of anatomy, the same name. So when we look at, you should do it. When we look at the masticator space, this really is synonymous with the infertemporal fossa. So anytime you see infertemporal fossa, basically just think masticator space. Now, when you talk about the retro maxillary space, when I think of the retro maxillary space, it's not really a true space. I just think of this more as a descriptor. It's any of this region right here behind the maxillary sinus. So if I see the maxillary sinus and someone says retro maxillary space, what that usually indicates to me, it would include this area right here. So that would include our little fremen right here, which is sphenopalentine fremen, the pterigral palentine fossa, and the pterigal maxillary fissure. And if you want to, it could probably include also some of the muscles of mastication, the anterior portion of the muscles of mastication. So in general, the infertemporal fossa to me is synonymous with the masticator space. And then the retro maxillary space, if you will, is this, that little area right here that's immediately posteriorly to the max, immediately posterior to the maxillary sinus. Please shed some light on the buckle space. Sure. So the buckle space is actually kind of an interesting space. If you will, it probably doesn't get enough love, if you will. So the buckle space, let me bring that up right here. It's essentially this area right here. So on the schematic illustration, it actually defines it pretty well. So ignore the area in red, but the buckle space is this area that's lateral to this clinical area that we refer to as the gingiva buckle sulcus. So what is the gingiva buckle sulcus? The gingiva buckle sulcus is the gingiva, which aligns the, is the mucosa line of the maxillary and the mandibular alveolar ridge. So basically it's our maxilla and our jaw. Then you have the buckle area, which is the mucosal layer aligned the inner portion of the cheek. So this is actually when you look in someone's mouth. So that's what we refer to as the gingiva buckle sulcus. Now, if we extend more laterally and we actually get into, if you will, the cheek structures, then we get into the buckle space. So the buckle space is the skin. And then we have the overlying soft tissues and then we have this deep fat right here. So for me, the buckle space is this area right here, which is lateral to the maxilla maxillary alveolar ridge and lateral to that and then medial to the mandible. And this fat right here is sometimes known as the buckle fat pad or the deep portion of the buckle space. The buckle space also contains this little duct right here, which schematically would represent Stenson's duct. We have the superficial muscles of facial expression, which include muscles like the obicularis oris. And then we have peripheral branches of the seventh nerve. And because we're in the buckle area, these are the buckle branches of the facial nerve. So when I think of the buckle space, I think of this sort of wrong border triangular area of fiber fatty tissue, which is lateral to the maxillary alveolar ridge and just medial to the ramus of the mandible that tends to extend posteriorly. Right. All right. How do we differentiate between deep low parotid tumors and parapherangeal lesions? Okay. So that's another great question. And again, I'm glad you ask it because it's always been and it always has been excuse me and continues to be an area of confusion. So what I will do is I will give you historically what I was taught with the understanding that I'm sure people will give you, if you will, different opinions. I've got a nice example, I think right here. So this is a, let's see, you can still see, right? Ashley, is that right? Yes. Okay. Great. So just to reiterate, let me go back one, yes, perfect. So just to reiterate, here's the triangular portion of the parotid gland here and then this is the retromandibular vein and just lateral to the retromandibular vein is going to be the facial nerve. So when we look at the facial nerve, here's the main trunk of the facial nerve and these are the various branches. So I had the privilege of being in Africa recently. So the mnemonic that I use this is actually to Zanzibar by motor car. So two is the temporal branch of the facial nerve. Zanzibar is the zygomatic branch by is going to be the buckle branch. Motor is going to be the marginal mandibular branch and car is going to be the cervical branch. So to Zanzibar by motor car. So that's the plane that separates a superficial from the deep lobe of the parotid gland. Now, when we look more deeply to the parotid gland, now we're going to see the parapherangeal space. So the question that we get into is whether or not a mass like this is actually involved in the deep lobe of the parotid gland or is it actually involving the parapherangeal space. So in this particular case, this was a pleomorphic adenoma and notice how this mass right here is extending through this area that it's located between the styloid process and the mandible. And this little area right here is referred to as the stylo mandibular tunnel. So if I see a pleomorph or if I see a mass right here is extending through the stylo mandibular tunnel, what we're classically taught is that if you see something extending through that tunnel, then this is a deep lobe parotid gland mass extending into the parapherangeal space. In fact, if you look at the opposite side, here's the mandible here, the styloid process is going to be right about there. In fact, that probably is a styloid process. So there's our stylo mandibular tunnel and you can see just a smidgen right here of deep lobe of parotid tissue. So you can see that if something arose from here, this would involve stylo mandibular tunnel. Now, if I show this case, notice how this mass is not really extending through the stylo mandibular tunnel. It sort of gets to that tunnel and it stops. So this mass is isolated in the parapherangeal space and it does make a difference in how these patients are treated because some surgeons, if it's involving the parapherangeal space, they may or the deep lobe, they may wish to just do a total parotidectomy through a parotid approach. But if we know that there's a substantial amount of involvement of the parapherangeal space or rising in the parapherangeal space, then some surgeons may elect to do a mandibular swing procedure because that will give them better access to the parapherangeal space. So for me, it's how much of this extension is going through the stylo mandibular tunnel. And if everything is medial to that stylo mandibular tunnel, then that suggests that it's primarily arising from the parapherangeal space. Dr. McCrary, how about one or two more and then we'll wrap up for the day? Does that sound okay? Yeah, it sounds great. Um, boy, oh boy. Should we just do it by who came first? Or perfect. Yeah, it's nice to have all this interest, right? Absolutely. Um, let's see on lymphoma PET CTs is the bilateral FDG of itty the parotid glands, normal physiologic uptake or an indication lymphoma disinvolvement? Again, another great question. If there is just diffuse uptake in the parotid glands, just diffusely uptake in the parotid glands, then that's usually indicative of just normal physiological uptake. Because the parotid glands contain individual lymph nodes, if I see a PET CT scan and I see multiple focal areas of increased uptake within the parotid glands like little balls, cannonballs or ping pong balls or now we can call them pickle balls, I guess, within the parotid gland that are round, then that's more suggestive of lymphoma. Whereas if it's diffuse uptake in the parotid glands, then that's really more indicative of physiological uptake. And then the next one is really quick. Will it be wrong to call a masticator space lesion as infertemporal lesion? The answer is no. I use the terms masticator space and infertemporal interchangeably. The next one real quick, that's quick. What all spaces are the infertemporal fossa consist of? The infertemporal fossa is essentially the masticator space like we talked about before. So should we just stop there and then we want to, Ashley, we can do a repeat of this later if you want or maybe another talk or something like that.