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Neurogenic Cough Treatment
Julia Casazza • Oct 30, 2023 • 40 hits
Neurogenic cough occurs following insult to the peripheral nerves or brainstem center (medulla oblongata) that control cough. Treatment of neurogenic cough initially involves medical management with neuromodulators and cough suppressants. Patients with cough refractory to medical therapy can undergo superior laryngeal nerve block or vocal fold Botox for lasting relief.
This article features excerpts from the BackTable ENT Podcast. We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable ENT Brief
• Post-viral chronic cough results when the coughing threshold is lowered following a viral infection. In many of these patients, decreased pulmonary reserve further worsens symptoms.
• Neurogenic cough is a diagnosis of exclusion.
• Treatment for neurogenic cough consists of cough suppression (with Tessalon Perles) and neuromodulation (with medications like gabapentin). Both medications are needed for maximum effect. A complete course of treatment can last up to a year.
• Superior laryngeal nerve block is performed in-office and can provide lasting relief to neurogenic cough patients unresponsive to medical therapy.
Table of Contents
(1) COVID-19 & Neurogenic Cough
(2) Neurogenic Cough Treatment with Neuromodulators
(3) Superior Laryngeal Nerve Block: An Office-Based Intervention for Neurogenic Cough
COVID-19 & Neurogenic Cough
Post-viral chronic cough, such as that seen in COVID-19 patients, results from a post-viral sensory neuropathy frequently exacerbated by poor pulmonary function. Increased coughing (as occurs during viral infection) lowers the coughing threshold in response to irritating stimuli, partially through changes to brainstem inputs and partially through injury to vagal nerve branches. Following infection, previously innocuous stimuli, such as cold air or ice cream, stimulate the hypersensitive larynx.
[Dr. Gopi Shah]
In terms of the post-COVID cough and airway complications, is this anosmia where-- but a lot of times the anosmia gets better, the cough gets better and you just see it maybe three to six months. Are these patients your long haulers where we still have a concern with this months later, years later? Have we been able to tease some of that out, or what have you seen?
[Dr. Karuna Dewan]
I'm not really sure. The patients that I see are people who tend to have been coughing for a while-- for several months already. I do have a small cohort of patients that are long COVID, the long haulers, and they have a lot of other symptoms too. I think the post-viral sensory neuropathy, these are patients that have post-viral reaction essentially. The superior laryngeal nerve is involved.
I think it's the same pathophysiology is when we used to see people with a viral bronchitis who had a cough that lasted a long time. Because they're also deconditioned in other ways, they have poor pulmonary function because of the COVID infection. A lot of times they'll have other neuropathies because of COVID. It just compounds their whole experience.
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Neurogenic Cough Treatment with Neuromodulators
Neurogenic cough – cough resulting from a hyper-reflexive state after an initial disease insult – is a diagnosis of exclusion. Lack of response to typical therapies (such as those for asthma, allergies, or reflux) and onset after an illness period clue the clinician into this diagnosis. Neurogenic cough can also occur as a part of paradoxical vocal fold motion (PVFM).
Treatment for neurogenic cough relies on neuromodulators, such as gabapentin, coupled with cough suppressants, like Tessalon Perles, to tamp down symptoms. Dr. Dewan begins treatment for neurogenic cough with gabapentin. If patients fail to respond after three months, she tries amitriptyline, then pregabalin.
[Dr. Gopi Shah]
Is this a good segue to get into some of the neurogenic, or are there other medications or being still in the differential?
[Dr. Karuna Dewan]
Yes, that's the diagnosis of exclusion. I think we've covered most of the other stuff. There's also paradoxical vocal cord motion, which can present as coughing. It presents as shortness of breath that can be triggered by coughing as well. That's something that's primarily treated. It's part of the irritable larynx picture. It's primarily treated with therapy. Basically, it's almost like a muscle spasm that's happening in the larynx, in the throat, and so you want to teach people to break that muscle spasm.
As I explain it to patients, which is a little oversimplified, when you get a muscle spasm in your calf, like you get a charley horse, you stand up and you stretch your legs. When you get a muscle spasm in your throat and you feel like your vocal folds are closing, you want to try and stretch. You want to try and open your vocal folds. We give them exercises to do that. Then if they're not getting the results they like, then we'll try an ipratropium bromide inhaler. It's an anticholinergic bronchodilator. We know how it works in the lungs.
We know how it works in the small muscles in the lungs. We don't necessarily know how it works in the larynx, but we know that it antagonizes the acetylcholine, theoretically preventing muscle contraction. In those patients that have exercise-induced cough or exercise-induced shortness of breath, we will have them do-- I tell them, "Do a couple of puffs before you're going to exercise, and then one puff every night." That's part of that irritable larynx picture.
The other portion of that is the neurogenic cough situation. Neurogenic cough is also described as laryngeal hypersensitivity. It's essentially a sensory neuropathy. It's usually post-viral airway hyperresponsiveness that persists beyond the resolution of the URI. We think the bad actor here is the vagus. It's vagal neuropathy, but it's a decrease in the cough threshold in response to irritating stimuli. As I tell the patients, there are things that were in the air that you encountered, cold air, ice cream, whatever it is, that didn't make you cough before, but now after you've had this illness, after the vagus nerve is irritated, those things are triggering a cough.
That threshold has changed. It makes patients more susceptible to chemical, mechanical stimulation of the cough reflex. Like I said, there are two arms to this treatment. There's a medication arm, and there's a cough suppression therapy arm. The medication arm-- This is the order that I do things in. I think everybody's a little bit different. I like to start with gabapentin. I'll do 100 milligrams TID for three months. I like gabapentin because out of all the neuromodulators, it has the least side effects. A lot of people have already tried gabapentin. Sometimes gabapentin is also the first line for diabetic neuropathy, and it's easy to get. It's easy for patients to pick it up from the pharmacy.
Superior Laryngeal Nerve Block: An Office-Based Intervention for Neurogenic Cough
Neurogenic cough patients who do not respond to medical therapy can undergo superior laryngeal nerve (SLN) block. Dr. Dewan performs this procedure in clinic, using a 1:1 combination of triamcinolone and lidocaine for anesthesia. Triamcinolone is long-acting, and lidocaine is short-acting. She injects superficially and bilaterally at the area where the SLN emerges from the thyrohyoid membrane. This area can be identified by palpating the area between the hyoid and the cornu of the thyroid cartilage. She performs three injections, each one month apart. Oftentimes, patients report long-lasting relief with this injection series. For patients who do not respond to injections, she performs bilateral Botox of the vocal folds, forcing them open and inhibiting cough.
[Dr. Gopi Shah]
That's how you counsel patients on outcomes like, this is what we should expect to see. In terms of how long-- I know some of the studies are coming out and it's new, what do you-- in your experience in terms of how long it lasts for, is that patient-dependent, or do you have a timeframe that you go by? If I can do these injections over three to five months and I can give them a good year or two, is that what we're looking at or this is a six to nine-month thing and then we're going to be doing the series again?
[Dr. Karuna Dewan]
A lot of people get better forever. Their cough goes away. What I try to do is, when people start seeing some benefit, then I space their injections out further. Instead of doing every month, if you're starting to see some benefit, I say let's go to six weeks, and the next time we're going to do two months. When we get to the point where we can go two months without an injection, they're usually better by then. They call you if they start coughing again.
[Dr. Gopi Shah]
This may be a very novice question. Do you have a scope or anything in their nose while you're doing the injection? There's nothing to look at, is there?
[Dr. Karuna Dewan]
No, there's no to look at because it's a relatively superficial injection. You can feel your hyoid. If you could feel your hyoid, you just put the needle down right there. There's nothing to look at.
Dr. Karuna Dewan
Dr. Karuna Dewan is an otolaryngologist / head and neck surgeon with Ochsner LSU Health in Shreveport, Louisiana.
Dr. Gopi Shah
Dr. Gopi Shah is a practicing ENT at UT Southwestern Medical Center in Dallas, TX.
Cite This Podcast
BackTable, LLC (Producer). (2023, June 20). Ep. 116 – Chronic Cough in Adults [Audio podcast]. Retrieved from https://www.backtable.com
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