Long-Term Loss of Smell from COVID

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Brian: It's The Brian Lehrer Show on WNYC. Good morning again, everyone. Loss of smell was one of the first defining symptoms of COVID-19, right? Especially, in the early days when tests were hard to find, the loss of smell served as a confirmation that no, you're not just under the weather, this is COVID. The vast majority of people who lose their sense of smell from the coronavirus get it back within six months the experts say, but six months with a diminished or lost sense of smell is a long time. A new meta-analysis of COVID data by the BMJ, that peer-reviewed British medical journal, suggests that approximately 5% of people with a confirmed case of coronavirus have suffered from a long term loss of smell or taste, defined as six months or more of dysfunction.

With hundreds of millions of COVID cases worldwide, that means millions of people around the world are likely still struggling with a loss of smell or taste. Now, we're going to focus on the loss of smell in particular. With me now is Dr. Zara Patel, professor of endoscopic, sinus and skull-based surgery at the Stanford School of Medicine, who specializes in smell disorders. Dr. Patel, thank you so much for joining us. Welcome to WNYC.

Dr. Zara Patel: Thank you. Thank you so much for having me

Brian: Listeners, have you lost your sense of smell to COVID? We want to hear from you. Has anything but time helped you? Tell us about the impact of losing the ability to smell on your life, or ask any question? 212-433-WNYC. 212-433-9692, or tweet @BrianLehrer. Dr. Patel, is there a consensus on what exactly about COVID-19 causes a loss of smell?

Dr. Zara Patel: Yes. I think that there's always research ongoing, and we learn more every day as more studies come out. In general, yes. We know that the SARS CoV-2 virus itself directly attacks the supporting cells within the olfactory epithelium, that little patch of the lining of the nose at the very top that contains your smell nerves. It doesn't attack the nerves themselves, just these supporting our sustentacular cells, and by doing so, it causes a lot of inflammation and damage within the entire system. A very common pattern that we see is someone will have a sudden loss of their smell and taste.

They, hopefully will recover. About 70 to 75% of people will recover within that first month, but then we have this 25 to 30% of people who either slowly recover but never quite back to normal, or they don't regain at all. Unfortunately, these are the people that we start seeing in our clinics, these long-term sufferers that just thought it was going to eventually come back, didn't have any intervention to help it come back, and then our suffering long term.

Brian: I hadn't heard that number before, that 25 to 30% of COVID sufferers lose their sense of smell long term. That's shockingly high to me. We say sense of smell, but this isn't just really just smell. Most of how we taste comes from the smell, or a part of it, so people are really losing two senses in a way.

Dr. Zara Patel: That's right. What we can sense from our tongue are just those very basic tastes like salt, sweet, sour, bitter, umami. Anything else about the flavor of your food, being able to really enjoy that roast chicken flavor or enjoy wine, understand the difference between vanilla and chocolate, that is all based on your ability to smell it. You can imagine how much enjoyment most people get from some food and drink. You can also imagine between all societies and cultures, no matter the geographic location, all cultures come together over food and drink, whether it's with your family, your friends, or strangers.

When you lose the ability to enjoy that, and unfortunately in some cases you begin to really be repulsed by these flavors and sensations, you can imagine how that leads to social isolation, anxiety, depression. It can really impact people's quality of life quite greatly.

Brian: Absolutely. Before we go to some phone calls, and you probably won't be surprised to know that our caller board has exploded incredibly, and right away. All our lines are full at the moment with questions about the loss of smell from COVID, and what to do about it. Before we go to the calls, I heard that some people experience more of an altered sense of smell, not lost maybe, but altered after COVID. What was a pleasant odor, smell is bad, or maybe even the reverse. Is that from the same cause?

Dr. Zara Patel: Yes, that's right. That's what we call parosmia, distortion of smell, or phantosmia, where it's just a phantom smell. Unfortunately, these are never pleasant odors. They're always some terrible smell that people sense. The reason is those supporting cells that I was talking about, they really are the key to directing the interaction of where these nerves go and are attached to, and making the right connection into the brain, olfactory bulb, the brain, all of that. The distortion really comes about when these nerves are either not a full complement so you're only getting a part of the signal, or they're just sending the wrong signal, an aberrant signal to the brain. That's how that happens.

Brian: Let's take a phone call. Nancy in Aberdeen, New Jersey. You're on WNYC. Hi, Nancy.

Nancy: Hi. Hi, Dr. Patel, and Brian.

Zara: Hi there.

Nancy: I was wondering if acupuncture would be a cure or help to getting, I don't know if it's my smell or my taste, I'm still confused, but to get my taste back or something. I was thinking of it, because-

Brian: Nancy, before we go to whether acupuncture or something else might work, can you talk a little bit about your experience? What happened to you, and how is it affecting you?

Nancy: Well, it's COVID-related, because I had it in May, and I'm just not tasting it fully. I had a hamburger over the weekend, and I couldn't tell the difference between the hamburger and the bun. I'm not getting full flavor. If I'm having maybe a piece of chocolate, I don't taste the full body of the chocolate. I might taste the fattiness of it. I've been sticking to cool foods like fruits, something that's interesting to eat, it's interesting in my mouth, or maybe even chips. I don't eat chips, but I like them because it's crunchy, or celery stuff.

That's what I'm sticking with. I don't go out to dinner, because I feel like it's a waste of money to buy food and then you can't really taste and enjoy it. It is a sadness, or even a little depression because of that I'm not enjoying something that I do enjoy eating, and tasting different flavors, and different foods. That phantom smell, I've had that, but not a lot of times. Sometimes I can smell something, and I ask my husband, and he says, "No, I don't smell anything." I'm having a little bit of everything, so it's a little frustrating. Six months seems like a long time, but I'm still eating. [laughs]

Brian: Wow. Dr. Patel, Nancy was so articulate about all of that, and she went to some of the mental health ramifications, as well as the physical sensory ramifications. I'm sure you hear both of those things a lot, right?

Zara: Yes. This is definitely mirrored in my patient population that comes to see me in my smell disorders clinic. I'm so sorry to hear how it's affected you. I know that's really difficult to deal. With regards to your question about acupuncture, what I can say is that there are no good studies showing that acupuncture can help someone bring back the loss of smell and taste, but there are some really good high-level evidence studies showing that there are some things that we can do to help people. I would ask you have you actually tried, or has any physician instructed you to try any of those things that actually do have a very high level of evidence that they can help?

Nancy: No, I haven't tried any physician. Is that what you were asking?

Dr. Zara Patel: Well, I would start there because although the rest of the world has become interested in smell only recently via the pandemic, people like myself and others have had an interest in the loss of smell and taste particularly from post viral dysfunction. COVID-19 is just one of many other viruses that can cause that, and many, many other causes of loss of smell and taste. We've actually been researching this. I personally have been researching this for over the last decade. We do have some good data that shows, regardless of the reason why you end up with this loss of smell, there are some things you can do.

For example, there's something called olfactory training which is, the way I explain that to my patients is it's like rehab. If you had a stroke and you lost function of one of your arms, you would go to physical therapy and work really hard to regain function of that arm. Well, olfactory training is the same exact thing, but for your smell. There is a very structured smelling protocol that you can start doing. It does take a really long time. I tell people to try not to get discouraged because it's not going to be some immediate dramatic fix. I have people do olfactory training for six months, because think of all those different millions of nerves that you have to regenerate and make the right connections.

If people stick with it, it can make a significant improvement in their ability to smell and taste again.

Brian Lehrer: What do you physically do during olfactory training?

Dr. Zara Patel: It's very simple actually. You just take something with an odor. Usually, I would say an essential oil is probably the easiest way to just get something that has a smell, but it could be anything else. It doesn't have to be anything in particular, but what's important is that you are familiar with the smell. You can remember what that smell is supposed to smell like to you, what it used to smell like to you. We start with four in general, the four that we start with are lemon, eucalyptus, rose and, sorry, clove. The reason we start with these four is that they are in different categories of smell.

They will stimulate different types of olfactory receptor neurons to hopefully wake back up and regenerate. The unique thing about the olfactory nerve compared to all our other cranial nerves, is that it does have this inherent regenerative capacity and, in people who are healthy, throughout our lifetimes the system is constantly regenerating. There are stem cells within the olfactory epithelium in our nose that create new neurons throughout our lifetime. We really just have to harness that natural capacity. We need to switch it back on and allow the system to work again on its own. That's what this does, this smelling.

Just bringing it to your nose, breathing in and out, there's no particular special way to breathe. It really is just a question of focusing your memory on what that used to smell like to you. Then I have people do that twice a day, every day. Again for six months, because it can take so long. The memory part is really important. Our olfactory cortex is directly next to our memory center and our brain, there is no intervening connection like with all of our other cranial nerves. That's probably why, when you walk down the street and catch a whiff of some potent smell, it can take you right back, immediately back, to some very vivid memory of yours based on that smell. That's what we're really using to try to recreate the correct pathway.

Brian Lehrer: That's fascinating. Nancy, I hope that's potentially helpful to you. Thank you very much.

Nancy: It is helpful. I didn't know, are you an ETN or should I get your information because I'm in Jersey, so I don't really know who to connect with.

Brian Lehrer: You're in California, right?

Dr. Zara Patel: Yes. I'm at Stanford University in California, so not there. Another great silver lining of COVID is that because there is now so many people suffering with this, the general ENT community has taken much higher interest in this. I've been giving talks on this now to the general ENT community for the last two to three years. Many more general ENTs are aware of olfactory training. There are other things also. For example, that was one randomized control trial I had done many years ago and others had done. There's another randomized controlled trial I did that showed that adding an anti-inflammatory medication to a sinus irrigation can bring down any residual microscopic inflammation within the olfactory cleft in the nose that would prevent the natural regenerative process from happening.

That's another thing that your local ENT could potentially prescribe for you. They'd probably look in your nose first and they could do that. There are other things extrapolated from a different patient population. For example, I'm not just a smell specialist. I'm also an endoscopic sinus and skull base surgeons who help people with sinusitis and people with skull-based tumors. There is a small percentage of people who have skull-based surgery, meaning going through the nose and going to the base of the brain and taking out a tumor in that area. Even when we are very careful to preserve the olfactory anatomy, there were some people that still had persistent smell issues after that surgery, probably from the big amount of inflammation that occurs in your nose after that surgery during the healing process.

I actually did a randomized control trial in that patient population many years back to see how I could help them. I was using a high dose Omega-3. The reason I used that was because there was a lot of really interesting literature coming out in the neurology field about how that could help many different areas of neurology, actually peripheral nerve injury, spinal injury, more central nerve problems. Because of the success that people were seeing and the regenerative properties that Omega-3 can help with in the nerve regenerative process, I used that and I saw a precipitous drop and the number of people that had persistence in the loss after that surgery.

Although I definitely tell everyone it's an extrapolation from a completely different patient population to COVID 19 or any post-viral smell loss, this end state of inflammation in the olfactory cleft is actually very similar. I do tell people about that also.

Brian Lehrer: Really interesting.

Dr. Zara Patel: That's another thing that you could ask your doctor about locally.

Brian Lehrer: Nancy, thank you again, I hope that's helpful. For a lot of our other callers who are asking basically the same question as Nancy, good to know that the ENT profession, ear, nose and throat physicians, are starting to get trained and schooled in this by people like our guest, Dr. Patel. I guess you can ask your own doctor folks if they know about this, or you could start Googling, I guess, to see who in our area or wherever you happen to be is familiar with olfactory training or any of these other methods. Another thing that I read about Dr. Patel that I gather some doctors are using is a kind of nasal injection of something called platelet-rich plasma along with electrical stimulation. Is that something you're familiar with?

Dr. Zara Patel: That's actually my research that you're talking about. Again, I am always looking at other medical fields to see what people are doing and seeing how I could potentially use medical innovations in other fields within my own field. The injection of platelet rich plasma is something that actually people do in a lot of different medical specialties. People in orthopedics are using it for cartilage regeneration and joints. People in the aesthetic industry are using it to give people facials and regenerate skin on their face. People inject it into this scalp for hair regrowth. It's used for a whole lot of things because platelet-rich plasma is rich in growth factors.

That is basically used all over your body to help regenerate tissue, whatever the type of tissue it is. I thought, well, is this really going to do anything for nerve? I read a really interesting study. This was some years back, a carpal tunnel syndrome study, which is a nerve injury really. The definitive thing for carpal tunnel is a carpal tunnel release surgery. A lot of people try medical therapy and physical therapy, things like that first. There was a three arm study that had people doing the medical and physical stuff. They had people getting surgery, the carpal tunnel release surgery, and then they had this arm of PRP injection.

Both the surgery and the PRP injection arms did much better than the medical arm. Not only that, but there was not a significant difference between those arms. That really convinced me that this was something real that I should try. I did a safety study, a feasibility study that took PRP, which is basically, you draw someone's own blood, you spin it down and get this very growth factor, platelet-rich concentration. You throw away the rest, all the red blood cells, white blood cells, all the rest of the blood and you just are left with this really growth factor rich portion of the serum. Then I injected it directly back into the olfactory cleft in people's noses. I proved that, yes, this was feasible.

People were able to tolerate this very well. I just numbed them up first, and this was very safe. I wasn't causing anyone to get worse. I wasn't causing anyone to grow tumors. That's also a really important thing to think about when you're injecting growth factors places. That very small number of patients that I ran this safety and feasibility study in, I show that it was safe and feasible. Now, as far as effectiveness, you cannot make any conclusions based on a small study like that. Although, I did see an interesting enough improvement in people's threshold, people's ability to pick up on odors in that study, that I decided this is worthwhile running a randomized controlled trial.

That's what led me to want to study it further. I set up the protocol of the randomized controlled trial and then COVID hit and so I basically converted that into a specific COVID-19 smell loss study, and I've actually just finished the study. We are going through data analysis right now. Now a lot of people around the country and the world actually are just doing it. They're just injecting the PRP based on that very small study I did many years back.I would caution people to say a randomized controlled trial, something with a placebo, that's really what tells us whether something works or not. I will be releasing that data very soon. I'll let you guys know if that is something that is actually affective, and that will help people. I suspect, just based on the patient feedback as we went through the trial, that it may be.

I would just tell people to wait for the actual data because that's really what we need in all of medicine, but particularly in this area where people are so desperate to try anything to help them. We need high-level evidence so people are not taken advantage of and just doing anything that they can that really won't help them in the end.

Brian Lehrer: My guest for just another few minutes is Dr. Zara Patel from Stanford University, who, as you can hear, has become an expert in researching and treating loss of smell from COVID. Nicole on Twitter has a question. Says, "Two and a half years after COVID, still diminished smell and phantom and distorted smells. Can't cook spices or smell gas leak. Phantom tastes are worse. Is there a link between sense of smell, taste, and brain issues like lack of focus and loss of memory from COVID?"

Dr. Zara Patel: That's a great question. There is actually some data emerging that loss of smell more than severity of the initial disease is actually the number one predictor of long-term cognitive dysfunction after COVID-19. That's likely because it is a mirror. Not just in COVID-19, but in all cognitive processes, the loss of smell is really this canary in the coal mine. It's this harbinger, this signal of what is going on with the rest of processing in the brain. For example, loss of smell is sometimes the earliest sign of Alzheimer's disease or Parkinson's disease. Loss of smell or dysfunction of smell is present in people with schizophrenia, with autism, with depression.

It is not surprising that people who have a long-term loss of smell are also very often the people that have long-term cognitive dysfunction from their COVID-19 infection.

Brian Lehrer: Darrell in the Bronx you are on WNYC with Dr. Patel. Hi Darrell.

Darrell: Hi. I caught COVID right before a trip that I had to go to Texas that I was actually looking forward to for barbecue. I was pretty miserable during the trip because I couldn't smell and I couldn't taste anything. Miraculously, I got it back like my first day in Texas. I had it for a few hours, but then I lost it like a day later. I've had that ongoing for the last two weeks, where I'll have the taste of something for a few minutes. I definitely taste it, but then yI don't taste anything or I'll lose it completely. Is this something that's a phenomenon that is common where people have actual taste, and then they lose it?

Dr. Zara Patel: Yes. That's very common. The way that the olfactory system recovers is all these nerves don't regenerate all at the same time. They're regenerating on their own cycle and schedule. During this entire regenerative process, it's common where people can initially smell or taste something, and then weeks to months, even later, they can have a complete loss again of that. That's because of what I mentioned at the very beginning, these supporting cells, these sustentacular cells are so key in the regenerative process. If they are not functional, even though the nerves themselves are trying to regenerate, they will not regenerate appropriately or correctly, or fully.

Therefore, when it comes time for that cycle to go through again, you may lose what function you had. It's also true that inflammation can persist even when people are feeling like they're breathing okay, they don't have any congestion or other nasal symptoms. The olfactory cleft is high, at the very highest point and deepest part of your nasal cavity. It's not in an area that you would sense airflow even. Inflammation can persist in this region. If there's a little bit of swelling or a little bit of inflammation, that may be a day where you're not able to smell or taste well, and then the next day the swelling comes down and you're able to taste again. That phenomenon is what led me to study that anti-inflammatory medication, to add to a sinus rinse because that can be very helpful with that type of phenomenon.

Brian Lehrer: As we run out of time, and acknowledging that besides the loss of taste that comes from the loss of smell itself, there are these psychological ramifications for some people. Anorexia at the extreme end, food aversions, malnutrition that can come from that. If you've lost your interest in eating, anxiety and depression, as one of the callers referenced. Not to mention that smells can be a big warning sign of a fire, a gas leak, things you don't want to be breathing like bleach or ammonia. That's another risk that comes along with this loss of smell for people. I think a lot of people have really been inspired listening to you go in to such detail about the research you've done on this.

Any advice for how folks can find ear, nose and throat specialists or anybody else in their areas who might be really up on the research that you and others in your field have done?

Dr. Zara Patel: Yes. The general ENTs, hopefully, will have been listening and learning during this pandemic about the different ways we can go about treating this. Specifically, if you live in a place where you can find a rhinologist, that's what I am. A rhinologist is a subspecialist within the ENT that just specializes in the nose and sinus and skull-based area. Those people are the most likely to be up to date on all this research that I and others have done. If you can find a rhinologist in your area, that would be the starting point. Unfortunately, there are just very few actual smell centers, I could probably count them on one hand, in the country. If you really wanted to go to a smell center that specialized in this you would likely have to travel unless you live in one of these places that really specializes in it, like Stanford.

Just finding a general ENT or specifically finding a rhinologist that specializes in the nose is your best bet. One other thing I'd add is just two things are the major predictors about whether or not we can bring someone's smell and taste back. One is your age. Unfortunately, no one has control over that. It's just that our bodies regenerate much easier when we're younger, obviously, any part of it. Number two is something you have control over. That is the duration of loss before definitive intervention. The sooner you go and seek care and the better you stick with these interventions without falling off, and then getting back on later, the better chance you have of regaining your smell and taste.

I wish I could tell everyone in the world that, because it's so common that I see someone a year or two years later after this has happened to them. It is just much harder for me to do anything to help those people, versus whether if I could get someone. I'd love it if I could just see everyone within a week of this happening, but that never happens. The sooner I can start treating someone, the more likely I am to be able to bring back some ability.

Brian Lehrer: Dr. Zara Patel, professor of endoscopic sinus and skull-based surgery, and I don't say that every day, at the Stanford University School of Medicine. Thank you so much for all your knowledge and advice. I know our listeners really appreciate it.

Dr. Zara Patel: Thank you so much for having me. It's been a pleasure.

 

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