A Trail to Sensory Neuropathic Cough

Introduction

A new clinical insight can be sparked when a physician encounters a series of patients in close succession whose stories overlap in some surprising way. This is an account of that sort, reviewing a trail of patients that led to understanding the clinical entity of sensory neuropathic cough.¹

Before the late 1990s, when the fourth patient described below opened for me a new thought window and initiated a substantial caseload of sensory neuropathic cough, only an occasional patient—not more than one or two per year—would ask for help with a chronic cough of a diabolical, life-changing sort. Examination would reveal nothing to explain the cough. If not already done by a prior physician, some tests and then empiric treatments would follow. The focus was always on the “usual suspects”: allergy, acid reflux, and cough-variant asthma.

Nothing ever worked for prior physicians or for me, until I saw the following four patients within a few weeks of each other and a new concept appeared: coughing initiated by a primary neurogenic sensory disturbance, analogous to neuralgia.²

Story One: Amitriptyline for Post-Herpetic Neuralgia

This woman was a longtime patient. She had a lively personality, matched by her hair color which, at the age of 68, she kept a vibrant red. Several years earlier, I had performed a supraglottic laryngectomy for cancer. She had been doing well for a number of years afterwards, and was here for a long-interval appointment. We caught up with the events of her life, and I examined her and pronounced all to be well.

Then she asked, “Could you look at my ear? It is really bothering me.”

I looked, and based on early findings and perhaps a single blister-like lesion, said to her, “I think you might be just at the start of shingles” (Herpes zoster oticus, in this case). A dermatologist confirmed the diagnosis and began treatment.

I didn’t see her again until her next six-month cancer follow-up. Within the visit, I inquired about her ear, and examined it. The bowl of her ear appeared healed, but scarred. She told me she was still suffering with ear pain, and that she was taking amitriptyline. “It definitely helps,” she said, “but I wish it did more.”

Story Two: Amitriptyline for Gagging as a Cousin Sensation to Neuralgia

The new patient questionnaire of the man in front of me said he was an electrician, 42 years old. His facial expression and other body language said “introvert.” After a handshake, introductions, and a sentence or two of pleasantries, I asked, “How can I help you?”

“I’m gagging,” he said, and looked at me.

“You’re gagging?” I asked, hoping he would elaborate. He only nodded “yes,” continued to look, and waited.

I followed with a series of questions. Each question was answered in a few words:
“If I touch my neck, it makes me gag.”
“I can’t button my shirt.”
“I have a hard time shaving [this part of my neck].”

After these kinds of answers, here was the look again, expectant, hoping that I would understand. But I didn’t. “May I touch your neck?” I asked.

He paused, as though considering, and then said, “If you want to.” I reached out and touched the front of his neck with one finger, at the level where a buttoned collar would meet. His response made me wish I had first asked him if he had just eaten. Five seconds is a long time to aggressively gag and heave.

When he finished, there again was the look of expectancy. My mind flitted through some different possibilities.

Could this be someone who has lived his whole life at the extreme end of the continuum of the gag reflex? I’d learned early in my career that, at one end of the gag reflex spectrum, there are some people who would be naturals as sword-swallowers. At the other end of the spectrum, I once saw a man who began to gag whenever I asked him to open his mouth, before I had even raised my tongue blade to within two feet of his lips.

But a hyper-gag reflex wasn’t the explanation. “No,” he said, “I’ve only had this for six months…. No, I never had trouble at the dentist before this started.”

My mind turned elsewhere. Might this be in some way behavioral? This man struck me as utterly grounded and low-maintenance, and I already believed this interaction completely, but I had to double-check. So, without asking again, I reached out and touched his neck again—same response, and again, entirely believable.

But then, my mind moved to a third idea. This has to be a neurological disorder. My touch to his neck had demonstrated a trigger phenomenon, as one sees in persons with neuralgia. And like neuralgia, the response was a sensory disturbance, but the difference was that, rather than pain, it was a gagging sensation.

Almost apologetically, I asked this man, “Would you mind trying a medication that might help?” The response was immediate: “Sure.”

I prescribed amitriptyline, at low dose, as I might for neuralgia. I didn’t hear from him for a few months, and so asked a nurse to follow up by phone. True to form, the information that came back was cryptic. “He says thanks. It worked.”

Story Three: Amitriptyline for a Non-painful, Non-coughing Sensory Disturbance

Her demeanor was “elderly,” and she was also large. I remarked inwardly how well she looked and how remarkable to live to age 75 at her weight. After introductions I asked my usual, “How can I help you?”

She said, waving to indicate her throat, “Oooh, doctor, I get a dry patch.”

Now, “dry throat” is not an uncommon symptom for which people seek an explanation and relief. So my mind went initially to things like medication side effects, Sjögren’s syndrome, and even insufficient fluid intake.

But answers to my subsequent questions did not fit those scenarios. The sensation was more than simple dryness. “It’s like the Sahara Desert,” she said at one point. Furthermore, the sensation happened suddenly and episodically, a few times a day. In fact, on a ten-point scale, the sensation was an instantaneous “8” for several seconds and then subsided to a much lesser severity for maybe another ten seconds before it went away completely.

Two things had caught my attention and made me slow down, circle around the problem, double-ask some questions in slightly different words, and listen deeply. First, she had said at one point, “When it happens, I just jump up and run to the kitchen for a glass of water, but it doesn’t help.” Jump up and run was said with emphasis and rising pitch. I had a hard time visualizing this particular woman either jumping or running. I felt compelled to understand this choice of words.

The second thing that caught my attention was her gesture. Her left hand indicated a specific place low in the left side of her neck. “Right here,” she said. She hadn’t used the fingers, thumb, and even palm as “dry throat” patients do to indicate the whole of the throat. Instead, she had done a two-finger point to a specific place. And when I asked her several minutes later to tell me again where the sensation was, she pointed to exactly the same place.

“I have a medication I’d like you to try,” I said. It was again amitriptyline, at low dose. (Today I’d give desipramine instead in her age group or, depending on response, gabapentin, citalopram, capsaicin spray, or other “neuralgia” medications.)

The response? After eight months of having struggled with what she viewed as a terrible problem, she obtained marked relief, even with the first dose of medicine.

Story Four: The Lights Turn On… Amitriptyline for Sensory Neuropathic Cough

(A few details below elaborated on from other similar patients, to give an “idealized” scenario)
This 46-year-old woman was desperate. Her chief complaint wasn’t a voice, swallowing, or breathing problem, such as for virtually all of my other patients. Instead, she was struggling with a cruel cough. In fact, for the past twelve long years, coughing had become a daily way of life for her.

In recent years, the problem had become more severe. She said she coughed hundreds of times every day, and it awakened her from sleep once or twice every night. Many episodes lasted only a second or two. She had stopped even noticing a lot of those.

About six times a day, the cough was much more aggressive and lasted an estimated 45 seconds. “I cough out a lung,” she said. “I turn red, my eyes tear, my nose runs, and I nearly (or occasionally do) throw up.” These episodes were humiliating when they occurred in public. “I once had someone come over to me in a restaurant and insist on giving me the Heimlich maneuver,” she said. “My husband practically had to fight him off.”

She further elaborated that she had to carry a spare pair of underwear due to occasional urinary incontinence. And to avoid a “scene” in public, she sometimes had to step away during church, a committee meeting, or when at the movies. Another problem was that she felt exhausted much of the time, because of her interrupted sleep.

I was only the latest in a long line of prior physicians. She estimated that she had seen eight or ten physicians, including one or more pulmonologists, allergists, gastroenterologists, and ENT physicians.

She had undergone numerous tests and all were completely normal or marginally abnormal. She had been treated, re-treated, and double-treated for asthma, even though she had no family history of this, and didn’t know what it was to feel short of breath, wheezy, or to have any chest symptoms. She was dutifully following doctor’s orders and using a steroid inhaler, though she hated it because each use tended to provoke an episode of severe coughing.

She had also tried allergy medication and treatment for acid reflux, again without having had the usual symptoms for either of these conditions—other than her cough. None of these medications worked either. Courses of oral steroids helped transiently, and codeine gave her longer spans of uninterrupted sleep. Still, in her mind, nothing was really working.

The arresting piece of information was that each episode of coughing was initiated by a sudden, compelling tickle. She could point to the location with one finger—exactly in the sternal notch. The sensation was the same every time—stereotyped. The only variation was that before the prolonged and violent episodes of coughing, the sensation was particularly urgent.

Just as for my gagging electrician, and for my “running and jumping” septuagenarian, the word “neurological” entered my mind. This cough was the result of a sensory disturbance. The resulting cough was not solving a problem, such as mucus that needed to be expelled, or infection, or responding to inhaled powdered sugar while eating a donut. Instead, this cough was the problem, caused by a primary sensory disturbance like neuralgia. In fact, for several years afterward, I would call this disorder “cough neuralgia,” before settling instead on “sensory neuropathic cough.”

I began to explain to this patient the concept of a neurogenic cough, and that I wanted her to try amitriptyline. She looked a little uncertain, possibly because my first-ever formulation was clumsy. Or perhaps it was because she had been told so many times that this was allergy, or acid reflux, or cough-variant asthma and was having trouble putting those diagnoses aside. Or perhaps it was because she was medically jaded. Who wouldn’t be, after all that she had been through, including visits to faraway and famous centers of expertise?

Amitriptyline doesn’t work for everyone (a second or third medication usually does in that case). Thankfully, amitriptyline did for her. She called the office two days later. “I slept through the night for the first time in 12 years,” she reported. After some additional tweaks and adjustments, she arrived at her final dosing strategy. She still coughs occasionally but only rarely violently. She also remarked that “my husband and co-workers are amazed.”

Sensory Neuropathic Cough Today

From that patient to the present, I look for chronic cough patients whose episodes are initiated by an abrupt and stereotyped sensation of tickling, sandpaper, pinprick, or the like. As is the case for neuralgia, many notice not only spontaneous attacks, but also some that are triggered: by talking, singing, taking a deep breath, touching a spot on the neck, breathing in cold air, changing position (such as when lying down at night), or encountering smoke or strong odors. Most patients describe a frequency, violence, and duration of coughing dramatically out of proportion to the other symptoms (if in fact any are present) of asthma, acid reflux, or allergy.

I rarely see patients with sensory neuropathic cough first, but if I did, I would not necessarily order any of the tests or treatments for allergy, acid reflux, or asthma. If a patient’s history matched sensory neuropathic cough well, and especially if the cough had been present for years, I would use professional judgment and common sense to individualize. In most cases, I would proceed directly to treatment for sensory neuropathic cough, without delay or sidetracks to “usual suspects.”

By now I have seen many hundreds of sensory neuropathic cough patients, several every month. An explanation of a primary neurogenic form of coughing is still new to all of them. I spend a great deal of time elaborating and drawing parallels to neuralgia, diabetic neuropathy, and the like. I caution them about medical jadedness so that they don’t give up in disgust if the first medication I recommend doesn’t work. And not everyone gets perfect results. Still, I’m thrilled whenever I meet another cough patient who I believe will find long-awaited relief, thanks to the surprising trail I was taken on by four patients many years ago.