Can’t stop coughing? What your doctors may be missing in finding the correct diagnosis for your persistent chronic cough.
It starts with an annoying tickle in the back of your throat at the most inopportune time (cue Jaws music). Halfway through the Sunday church service, just as Father Mitchell leads his closing prayer (♫♫dunn…. dunnn…), seconds away from a minister asking a wanton groom to kiss his blushing bride (♪duunnn… ♪dunnn… ♪dunnn… ♪dunnn), or when you are asked to give a lecture on your favorite subject to a group of friends and colleagues (♬DUN DUN DUN DUN DUN ♬…. insert shrill tuba noises ♬ ♬ ♬ ♬!!). A tiny bead of perspiration accumulates on your temple. You fidget briefly in your seat in a vain attempt to stop the physically irritating and emotionally embarrassing event about to unfold. The tickle gives way to what feels like uncontrollable chest convulsions producing a dry hacking cough arising from the upper throat. Suddenly eyeballs everywhere focus in on you like laser pointers. Some are sympathetic but most are accusatory, asking, “Are you seriously SICK out in public?”, “Who does that??”
For many Americans, inflammation involving tiny nerve fibers within the laryngeal nerves signal the brain to produce a maddening, non-acquiescing cough. Most of us have probably experienced a post-infectious cough that seemed to overstay its welcome following a particularly uninvited upper respiratory tract infection. But for thousands of people, laryngeal sensory neuropathy (LSN) or sensory neuropathic cough can be a momentarily incapacitating condition affecting not only their health, but also their quality of life.
Work-up of a typical cough patient includes a thorough medical history to assess for keywords to clue providers in as to which diagnostic procedures to order. Common culprits for chronic cough include asthma, postnasal drip, chronic obstructive pulmonary disease (COPD), gastro-esophageal reflux disease (GERD), postnasal drainage, eosinophilic bronchitis, infections (eg the flu, common cold, acute bronchitis, pertussis, tuberculosis), blood pressure medications such as angiotensin-converting enzyme (ACE) inhibitors, bronchiectasis, sarcoidosis, lung cancer, cystic fibrosis, aspiration, and sometimes even heart disease.
Picture each question asked by a provider about a particular symptom as a fork in the road. Did your cough start after a recent upper respiratory tract infection? If yes, the path points towards an acute (likely self-limiting) issue that may resolve with medications (eg antibiotics, steroids, and cough suppressants). Do you experience heartburn? If yes, providers would take the direction of trying anti-reflux therapy to manage cough and associated symptomatology. Are you a smoker? (FLASHING RED SIGN); consider performing a chest X-ray to assess for sinister pathology.
Patients with chronic cough (over 8 weeks) require a closer look. Physical examination and auscultation is critical. Adventitious breath sounds should be addressed and chest radiography considered. Evaluation for chronic cough includes a battery of tests addressing each individual underlying disorder that contributes to cough. Pulmonology evaluation includes chest x-ray, CT scans, sputum cultures, bronchoscopy, and pulmonary function tests. Otolaryngologists perform flexible laryngoscopy, sinus scans, and sometimes allergy testing to delineate underlying issues contributing to cough. Gastroenterology workup includes esophagogastroduodenoscopy (say that three times fast) otherwise known as EGD.
Treatment is usually causality driven and can include antibiotics, cough suppressants, anti-reflux therapy, asthma medication, antihistamines, steroids, and decongestants depending upon the underlying diagnosis. Symptomatic relief is also recommended as in rest, fluids, smoking cessation, and humidified air. But what do you do when you’ve exhausted appropriate therapy recommendations for common cough culprits? It’s time to think outside the box and explore the possibility of LSN.
Laryngeal sensory neuropathy is a neural disorder specific to the larynx thought to arise from irritation within the laryngeal nerves leaving them overly sensitive to the slightest stimulus. A droplet of mucus… a whiff of perfume…. a breath of air… any number of things can innervate a LSN patient causing a seemingly unbreakable coughing spell. Accompanying symptoms can include globus (or lump sensation), frequent throat clearing, and sometimes swallowing issues. Consider evaluation for LSN when treatment for common chronic cough culprits such as asthma, allergies, and reflux have been evaluated and managed.
Diagnosis is usually through process of exclusion. An extensive workup is required to exclude all other causes for cough. New diagnostic tests are currently on the horizon. The SELSAP or Surface Evoke Laryngeal Sensory Action Potential is a sensory nerve function test that provides non-invasive examination of the laryngeal nerve by placing external electrodes to the side of the voice box and under the chin. A mild stimulus is elicited behind the ear and waveforms are measured to detect abnormalities involving the nerves.
A high index of suspicious symptoms coupled with adequate treatment for additional underlying conditions contributing to multifactorial cough may be an indicator that treatment for LSN is appropriate. Medications used to treat LSN include those aimed at “calming” the laryngeal nerves. Amitriptyline (Elavil), tramadol (Ultram), desipramine (Norpramin), gabapentin (Neuronitin), and pregabalin (Lyrica) are used to treat other types of neuropathy and can be helpful to those suffering from LSN. Medications are usually taken from 3-6 months and then slowly phased off based on clinical course and patient preference. Severe refractory cases may be candidates for Botox injections into the thyroarytenoid muscle involving the larynx.
Cough is a symptom and not a medical condition. Its prolonged presence warrants the need for further evaluation. A thorough medical history, physical examination, diagnostic testing, and endoscopy play an integral part in evaluating the cough patient. After all common cough culprits have been properly treated or excluded, providers should consider evaluation for laryngeal sensory neuropathy. Before the Jaws soundtrack precipitating a LSN coughing bout swallows you whole, consider evaluation for chronic cough.
Kari Kingsley, MSN, CRNP works as an otolaryngology nurse practitioner in collaboration with Dr. Neeta Kohli-Dang. Together they share nearly forty years of ENT experience. They treat dizziness, ear infections, hearing loss, nasal congestion, sinus infections, thyroid nodules, tonsillitis, neck masses, hoarseness, trouble swallowing, and a multitude of other ear nose and throat conditions. Please call 256-882-0165 to schedule an appointment with Dr. Neeta Kohli-Dang and Kari Kingsley or visit Huntsville ENT.
This article was written for and published by Inside Medicine.