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June 26, 2010

Laryngeal Sensory Neuropathy (LSN) Chronic Cough Treatment Failure

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Laryngeal sensory neuropathy (LSN) is a recently described condition felt to cause a chronic cough in patients when treatment for everything else (allergies, asthma, reflux, etc) has been evaluated and managed. Treatment for this condition is with neuropathic medications including neurontin, elavil, lyrica, nortriptyline, etc.

In the past few months, I have seen a few patients referred to me with chronic cough treated with these medications with minimal or no improvement. OR... the cough initially improved with such medications, but than over time, stopped working.

All these patients reportedly had a full workup with everything being normal and as such, was diagnosed with LSN. These patients were being solely treated with neuropathic medications and nothing else.

On review of their old records, it became apparent to me that these unfortunate patients actually suffered from MULTIPLE causes of cough that was not being treated. A common condition missed or not treated in these patients was non-acid reflux which can only be diagnosed on 24 hour multichannel impedance testing. Another more common scenario was the presence of mild acid reflux and allergies based on minimal reactivity on allergy testing and reflux that was present, but within normal range on 24 hour testing. Medications for allergies and reflux were tried, but didn't help and so was stopped. (Of note, none of the patients (prior to cough) ever had symptoms of reflux or allergies.)

WRONG!!! Treatment for both should have continued and very aggressively. Why?

Patients need to keep in mind that it is not unusual that a patient may have SEVERAL factors of cough as well, ALL of which need to be treated in order to resolve a persistent cough. Because laryngeal sensory neuropathy results in a hypersensitized larynx, problems with reflux and allergies which ordinarily would not cause a cough (or any other symptoms) in normal patients, will now cause a persistent cough. (This situation is even applicable in patients who have NEVER had any symptoms of allergies and reflux in the past.) In other words, though allergy testing may reveal only mild allergies and 24 hour pH study may show reflux episodes within normal range, these "mild" problems now need to be treated aggressively along with the neuropathy. To reiterate... laryngeal sensory neuropathy is a hypersensitized larynx. In this hypersensitized state, even a little bit of reflux or allergies will trigger a cough which normally would not. Each and every one of these conditions need to be treated aggressively to cure a persistent chronic cough.

The lack of treatment for each and every known cause of cough (even if mild) is the most common reason why treatment of laryngeal sensory neuropathy fails with neuropathic medication.

Case Report:

To illustrate, here is one case I saw a few months back...

Middle-aged patient who has had a chronic cough for about 15 years. Had a full workup done and found to have mild allergies to only alternaria mold (class 1) and dust (class 2). He did not respond to allergy medications and so these meds were stopped. Reflux workup did show significant reflux and so underwent nissen fundoplication which did help the cough by about 30%. His doctor than diagnosed him with LSN and tried him on a variety of neuropathic medication with some, but incomplete improvement. I was than asked to help figure things out.

The first thing I did was to instruct the patient to continue with the neuropathic medication that seemed to work the best for him (elavil 50mg twice a day). I also started the patient on allergy shots as well as an antihistamine and steroid nasal spray. I repeated a 24 hour pH and impedance testing to see if there was STILL reflux going on in spite of the reflux surgery. Lo and behold, there WAS both acid and non-acid reflux occurring, but on the high end of normal (much better than before his surgery). Based on this result, I restarted him on reflux medications daily.

Within 3 months, his cough completely resolved. I slowly tapered the elavil off. Once we both were convinced that his LSN was cured, the daily reflux medication was stopped and used only as needed. Allergy shots could have been stopped as well, but patient elected to continue them, but he no longer needed the daily allergy medications.

SO... what happened?

This patient apparently had allergies, reflux, and laryngeal sensory neuropathy causing his cough. Given he was being treated for only LSN prior to seeing me, that was why he had incomplete improvement of his cough.

I aggressively treated for all 3 factors of his cough. The mild allergies and reflux were brought under tight control preventing them from constantly (even if mildly) irritating his hypersensitized voicebox. Once his voicebox was in an "clean" environment, it was able to heal and desensitize with elavil. Once the voicebox was returned to a normal state, the reflux and allergy was now able to be treated like any other normal person.

The key thing to remember is that patients with LSN belong to a totally different sub-population of patients with a cough. One can NOT treat them as if they are part of the normal population. "Normal ranges" of reflux and allergies do not apply which actually makes sense if one realizes the voicebox in patients with LSN is hypersensitized.

What if EVERYTHING truly did come back normal?

There are 2 things I've done in this situation where there's absolutely no evidence for any abnormalities on any testing, mild or otherwise.

Botox injections to the thyroarytenoid muscle of the voicebox (similarly for spasmodic dysphonia treatment).

OR

Starting combo therapy using two different neuropathic medications, each of which seemed to help singly.


To read more about chronic cough due to LSN, click here.

Of note, SELSAP is a promising test to evaluate for laryngeal sensory neuropathy.

References
  • Management of Recurrent Laryngeal Sensory Neuropathic Symptoms. Norris BK, Schweinfurth JM. Ann Otol Rhinol Laryngol. 2010; 119:188-191. Link
  • Chronic cough as a sign of laryngeal sensory neuropathy: diagnosis and treatment. Lee B, Woo P. Ann Otol Rhinol Laryngol. 2005 Apr;114(4):253-7. Link
  • Gabapentin in the Treatment of Intractable Idiopathic Chronic Cough. Mintz S, Lee JK. Am J Med. 2006; 119(5):e13-15. Link
  • Laryngeal Neuropathy as a Cause of Chronic Intractable Cough. Mishriki YY. Am J Med. 2006; 119(5):e5. Link
  • Sensory neuropathic cough: a common and treatable cause of chronic cough. Bastian RW, Vaidya AM, Delsupehe KG. Otolaryngol Head Neck Surg. 2006 Jul;135(1):17-21. Link
  • Effectiveness of amitriptyline versus cough suppressants in the treatment of chronic cough resulting from postviral vagal neuropathy. 2006. Jeyakumar A, Brickman TM, Haben M. Laryngoscope 116(12):2108-2112. Link
  • The irritable larynx syndrome. Morrison M, Rammage L, Emami AJ. Journal of Voice. 1999;13:447-55. Link
  • Vagal neuropathy after upper respiratory infection: a viral etiology? Amin MR, Kaufman JA. American Journal of Otolaryngology, 2001;22(4):251-256. Link
  • Cough and paradoxical vocal fold motion. Altman KW, Simpson CB, Amin MR. Otolaryngology-Head & Neck Surgery. 2002;127(6):501-11. Link
  • Botulinum Toxin A: A novel adjunct treatment for debilitating habit cough in children. Sipp JA, Haver KE, Masek BJ, Hartnick CJ. ENT Journal 2007;86(9):570-572. Link
  • Use of botulinum toxin type A for chronic cough: a neuropathic model. Archives of Otolaryngology-Head & Neck Surgery. 2010;136(5):447-452. Link
  • A new treatment option for laryngeal sensory neuropathy. Halum SL, Sycamore DL, McRae BR. Laryngoscope. 2009. Link
  • Postviral vagal neuropathy. Rees CJ, Henderson AH, Belafsky PC. Annals Otol Laryngol Rhinol. 118(4):247-52, 2009. Link

5 comments:

  1. I was diagnosed with LSN a few months ago (after reading about it on the internet). My cough has been a recurrent problem for about 40 years. Treatment with 100mg of amitriptyline once a day has stopped more than 95% of the cough symptoms. Adding treatment for "allergies" or "reflux" would be ridiculous. My ENT also agrees with that. I've had multiple diagnoses over the past 40 years and one sinus surgery. The success of my current LSN treatment is definitely a life-altering success.

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    Replies
    1. But what if your cough returned to be as bad as BEFORE taking amitriptyline even though it may have helped initially? For those who experience this situation or the cough does NOT get better with amitriptyline, that's who this article is meant for. Your particular situation is probably purely due to LSN without other issues. As such, stating treatment for allergies or reflux is ridiculous is unwarranted.

      Delete
  2. For 40 years, I have had a cough that starts and will not end for weeks, months or longer. I've seen at least 12 ENT's and other doctors to get an answer into what caused my cough. A couple months ago, I managed to stop the cough by almost 100%. How? The past few years the cough has been mild compared to other periods in the past 40 years. I have bad sacroiliac joints and had been prescribed 50mg of amitriptyline to help with nerve pain and to help with sleep. I had my sacroiliac joints fused a couple years ago and decided to ween myself off the amitriptyline in the spring of 2013. At the same time, the persistent cough returned with a horrifying vengeance. All of this summer was spent coughing and not feeling well. Reading through the years of comments on this page brought me to an undeniable cause of my cough: laryngeal sensory neuropathy. It had never occurred to me that the cough had been somewhat controlled by the amitriptyline I'd been taking for several years. I still had some amitriptyline pills and a refill, so I started to experiment with increasing the dosage beyond 50mg. 75mg worked better to control the cough, and 100mg worked even better. I actually had just seen an ENT a week or two before discovering the cause of my cough. So I wrote him a letter explaining that I had found a solution to my cough and made a new appointment. He agreed that laryngeal sensory neuropathy was a correct diagnosis and was happy to prescribe 100mg of amitriptyline per day. I'm 51 years old and have spent thousands and thousands of dollars on doctors, medications, tests and sinus surgery for my cough. But those days are over now. I'm thrilled not to cough or to fear the next recurrence of the dreaded cough that wouldn't go away. For me, the irritation was only on one side of my throat. The amitriptyline does cause an irritating dry mouth at 100mg a day. The ENT did say that I could ween myself off the amitriptyline until the next time the cough started again. I'm absolutely THRILLED to live life without the horrible cough, so I'm also a bit reluctant to stop taking the amitriptyline. I read some comments on this thread from people expressing a reluctance to take an anti-depressant for the cough. It's necessary to understand that medications like amitriptyline are used for other purposes. For me, amitriptyline has been used to treat nerve pain (sciatica) and for my laryngeal sensory neuropathy. I could care less what the purpose of amitriptyline happens to be, because IT WORKS. My cough is gone!

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  3. I am an otherwise very healthy 38 year old male that has been suffering on and off from a diagnosed Sensory Laryngeal Neuropathy. It came about because of a freak accident 1 year ago when a cold pill was stuck in my throat for several hours. Ever since, I get a stabbing globus sensation right in the area where my adam's apple lies. I only cough when the globus sensation is very pronounced such as after drinking coffee or eating spicy foods. Initially,my globus was so severe that I could not work for 3 months (I am a technical Instructor). The greatest discomfort was insatiable gag reflex. I had to lie down most of the time to get relief. I took 2400 mg of Gabapentin for 2 months but could not tolerate the side effects. I was about to begin my Elavil treatment but instead decided that TIME would be the best medicine. Then magically, after 6 months, it went away (Only for me to acquire a Perilymphatic Fistula that still persists today.... I continue to believe that some how both ailments are somehow related....via the VAGUS nerve or reaction to extreme stress perhaps!) I was free from globus for about 6 months...then about 3 weeks ago. It came back! Why did it come back? I would assume the hyper sensitized laryngeal nerve heals in a linear fashion incrementally getting better. I am perplexed as to why it returned. Any thoughts? Suggestions?

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  4. Can you recommend any skilled practitioners in the Detroit area as knowledgeable as you or more in this matter who will take this seriously and understand the nuances of LPR,NA Reflux, and LSN. I have never heard any of my doctors, dentists, or specialists mention LSN or NA reflux EVER and I seriously want to fix my physically declining and psychologically defeating chest and voice issues which sound extremely similar to everything you are saying here. Albutorol doesn't work. Prilosec helped for a while, but seems to be less and less effective years later to the point of pointlessness. And ceterizine doesn't do much of anything. Is there a word to define this specific type of ENT who focuses on such issues? If not, why has it never been mentioned to me that it could be a nerve issue?

    ReplyDelete

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