David Prologo, MD, FSIR, an Interventional Radiologist at the Emory University School of Medicine, and Diplomate in the American Board of Obesity Medicine, talks about cryotherapy for hunger management, how it works, and who are the best candidates.
Interview conducted by Ivanhoe Broadcast News in April 2018.
For permanent weight loss there’s no simple solution it seems and there’s always diets. And then there’s gastric bypass surgery. What is suppressing the hunger nerve?
Dr. Prologo: I’m glad that you asked it that way because I think that the solution for long term weight loss is simpler than you might think, at least simple to understand. The reason people yo-yo diet is because they don’t reach this critical point. You have to stay engaged for a certain amount of time and then these things get easy. A lot of the folks who are trying to lose weight now will come off the couch and start a diet and exercise program and it lasts 7- 10 days, maybe a little bit longer and then quit. And so they don’t reach this point where everything changes and everything gets easy. If we can keep people engaged long enough to reach that point then dieting, eating clean and exercise becomes fun, it becomes easy and no longer is a drain. That’s the point of this procedure. We freeze the hunger nerve, and I’ll tell you how in a few moments, to decrease or to make it easier to stay on this calorie restriction long enough to reach that point. Once folks reach that point they don’t need us anymore. We’re just trying to lower the entry barrier.
So it’s almost like a tool to get to that point. What is this procedure, we hear of cryotherapy, we hear of things cryo, what do you call it and did you stumble upon it treating other conditions?
Dr. Prologo: It’s important to understand and to answer this question that when people embark on a diet and exercise program there’s a big difference between the experience of a lean person and the experience of a person who is overweight. The person who is overweight has a huge number of negative signals sent back to the brain when they start a diet and exercise program. What we wanted to do was decrease that backlash. The way that we did it was we used a cryoablation probe and put it next to the hunger nerve and shut down the signals. So now when folks restrict their calories as part of a diet they don’t get that huge backlash of negative feelings. It’s a little bit easier for them and they can stay on longer.
It’s called cryoablation and it’s a procedure, is it invasive and what are you doing exactly? How are you doing the freezing?
Dr. Prologo: The way that the procedure works itself, cryoablation is a therapy that we as interventional radiologists, have used for many years to treat cancer, to treat cancer pain and then to treat pain by shutting down the signals and nerves that were carrying the pain. Now what we do is we take a probe which is about the size of a pen tip, we use our CT scanner to guide that probe to the place that we want. In this case the junction of the esophagus and the stomach. We decrease the temperature to minus forty degrees in a very small area, one centimeter by two centimeters. And thereby decrease the signal in the nerve. We take the probe back out and we put a band-aid over the puncture site and the patient goes home.
How long does that take?
Dr. Prologo: The procedure itself takes about 20 to 30 minutes. The freeze portion is two minutes long.
Once you freeze it, is it done? Or does the patient have to go back? What are the effects?
Dr. Prologo: I’m glad you asked this question. We know from freezing nerves in a periphery for pain that the nerve will shut down, it will undergo a predictable sequence of events and then regenerate over about 8 to 12 months. But in this case we only need that eight to twelve month window to get people over the hump.
How did you find that specific area? How did you know that area was going to control and how does it control a person’s hunger or desire to eat?
Dr. Prologo: There’s a subspecialty of medicine called obesity medicine and certification under a body called The American Board of Obesity Medicine. The answer to your question is a lot of work has gone into obesity medicine research and bariatric research, which is obesity medicine procedures during the last 10 to 20 years. We live in time of explosive research around bariatric interventions and obesity medicine research. During the last 10 to 20 years we’ve learned more than we’ve known in the previous 100 years about the mechanisms of obesity and the mechanism of weight loss. Part of which is the function of the vagus nerve, which carries signals from an empty stomach to the brain inducing food seeking behavior.
Say that part again Doctor. Because I think that’s important about the vagus nerve.
Dr. Prologo: Got it, all right. We live in a time of explosive research around bariatric interventions and obesity medicine research. Part of what has come out of that research is the function of the vagus nerve, which carries hunger signals from an empty stomach to the brain inducing food seeking behavior based in survival.
Are you freezing the vagus nerve?
Dr. Prologo: The vagus nerve comes down and divides into two parts; we are freezing one of those parts.
And like you said that freezing will last up to a year?
Dr. Prologo: Approximately, and that’s extrapolating from things that we know about freezing nerves in the legs and the arms for pain. What we’re trying to do by decreasing the signals in that nerve temporarily is open up a window for folks to get through so that they can live healthy on their own.
Talk about the clinical trial that’s going on here at Emory and what success have you seen so far?
Dr. Prologo: So far we’ve done the procedure on twenty patients which is the total number to be enrolled in this trial. Ten of those patients have been followed out for the entirety of the study to six months. The remaining ten are in some degree of follow up. We’ve seen approximately an average of 15 percent total weight loss overall and we’ve seen about five percent of excess BMI lost. What was striking about following all 20 of these patients out to more than 50 time points for all of their follow ups is that 99.5 percent of them report decreased appetite.
The cryoablation procedure freezes that hunger nerve and the idea is to for that period of time that it decreases the hunger, or the sense that you need to eat, it decreases that to a point where the eventual goal would be that they would just feel that way on their own. Would their stomach shrink?
Dr. Prologo: The idea of stomach shrinking actually or having a smaller stomach with which to fill food was the original thinking behind gastric bariatric bypass surgery. But what we have learned over the years is that the size of the stomach or the capacity of the stomach is not related to the weight loss following any of these interventions. What’s actually happening both during the surgeries, doing this procedure and others is that hormonal changes are taking place over time in the hunger hormone system. So over that one year the body will readjust to the absence of the hunger signal and create a new set point.
And then that would be the set point from that point on if they continue to maintain a healthy lifestyle.
Dr. Prologo: At that point they’ll want to. That the goal.
So it’s mental as well?
Dr. Prologo: Not mental, glad you said that. Absolutely not mental actually, that is such a good point. We hope to actually debunk the thinking that it’s mental at all. And in fact the larger picture here is that when folks come in with a state of disease, obesity is a state of disease. It can be compared to heart disease, it can be compared to diabetes, it can be compared to eczema. And it requires a treatment from the outside in. We don’t tell anybody else to will away their medical condition and I don’t want to us to do that anymore for folks who are overweight or obese.
This needs to be treated as a medical condition?
Dr. Prologo: Absolutely. And what happens is a change from the outside in. The obese or overweight person who abruptly stops eating as much immediately feels these overwhelming hunger signals. We want to dial that down. But none of this is related to willpower or mental strength.
Who would be a good candidate, this is not available at the moment for weight loss or is it?
Dr. Prologo: Not yet. Available soon we hope, we’re working out the details on how to roll it out. But the perfect candidate is the person who doesn’t qualify for bariatric surgery. BMI’s that are under forty but still over weight. The ideal candidate for this is the person who is overweight but doesn’t quite qualify for bariatric surgery so BMIs from about 30 to 40. But we can dial that down even more by saying the perfect candidate is that person who has tried diet after diet, who feels hope and motivation and excitement at the beginning of a diet, makes it out 7 to 10 days and then can’t go any longer. It is that person that we want to ease the experience for them and get them all the way to the other side.
Any risk involved?
Dr. Prologo: There is always a risk with any procedure, small risk of bleeding, small risk of infection. We haven’t seen any complications or adverse events in our current cohorts so far.
Can you talk about Melissa quickly because you’ve seen a lot of success with her?
Dr. Prologo: Melissa is actually the perfect example of what we are trying to accomplish with this diet. Melissa is someone who has tried many other diets in the past all of which would work if the person could see them through to completion. It’s not the diet or exercise program itself that’s not succeeding, it’s the person’s inability to stay engaged long enough to see results. With Melissa we were able to decrease the response that she feels when she starts these diets. Keep her on them long enough to where she’s turned the corner and now everything is fun.
Any side effects that you’ve heard about?
Dr. Prologo: Not so far.
So no side effects obviously you have to be willing to do the procedure and really it reduces your hunger signal? It doesn’t get rid of it all together?
Dr. Prologo: It reduces it, there are several redundant systems in the body that send hunger signals to the brain so that we can seek food and we can survive. We are only taking out one of those to dial down the overactive response that overweight and obese people have.
In other words there is a good candidate for this kind of procedure. And your hope is how soon or far away are we from this?
Dr. Prologo: I think we’re hoping to roll out the entire package including the procedure and the before and after obesity medicine formal care by early 2019.
You have to have special equipment for this, you have to know what you’re doing.
Dr. Prologo: You do have to have interventional radiology training to perform this procedure. We are subspecialists who use advanced imaging guidance like CT or MRI to safely guide these needles to places of interest, in this case to the vagus nerve.
If people wanted to learn more about this where should they go? Is there a good site?
Dr. Prologo: There is, Emory has a website which is available to anyone interested in potentially signing up for a future trial or learning more. It is http://radiology.emory.edu/FreezeYourHunger.html
Anything else you want to say? Some people might think this is a simple solution. You’re not trying to say go in to all of this lightly?
Dr. Prologo: Right. You ask the best questions. Specifically this procedure does not cause weight loss. What this procedure does is make the experience of healthy eating, calorie restriction and exercise easier. This is a procedure to make that experience easier for folks who aren’t able to tolerate it currently.
You still have to be committed and willing to do the work, that’s the issue.
Dr. Prologo: Exactly. The procedure itself will just make it easier for you.
This is not just for weight loss, this procedure you have used for other conditions.
Dr. Prologo: Right. And because the advance imaging guidance and our skill set as interventional radiologists allows us to reach places deep in the body that otherwise were not accessible we are able to target nerves that cause pain syndromes as well. And by freezing and turning down the signal in nerves that are causing pain we’re able to offer an alternative to opioids for many pain related syndromes.
These people can get off the pain meds with this procedure?
Dr. Prologo: Indeed or we can perform this procedure in a patient with pain, cancer related pain or other before they start opioids.
And this is all about freezing? Can you talk about you’ve done it on phantom pain patients?
Dr. Prologo: Some of the examples where we can use this procedure as an alternative to opioids are cancer related pain, phantom limb pain, pelvic pain, back pain and a few others.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Alysia Satchel, Sr. Media Relations Manager
Emory Johns Creek Hospital
678-474-8018
alysia.satchel@emoryhealthcare.org
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