Sensory Neuropathic Cough

There are patients with a chronic dry cough lasting longer than 6 months that seem to defy all explanation and resist all of the usual standard treatments. Some patients have coughed for more than ten years resulting in frustration not only in the terms of treatment, but diagnosis. Medications are reviewed, as some are known to cause cough as a side effect (such as ACE inhibitors). Patients are often told their cold is due to reflux, allergy, asthma, virus, etc. and undergo numerous tests such as a pulmonary function test, a chest x-ray, an upper endoscopy, an esophagram, CT scans, MRI scans, etc. Proposed treatments with antibiotics, proton pump inhibitors, allergy medications, cough suppressants, steroid inhalers, etc. are not successful. Eventually, some are told it’s all in their head or the cough is idiopathic.

A typical patient with the chronic cough is described as follows:

-Started during or after recovering from a viral laryngitis

-Dry cough

-Cough occurs due to no perceivable reason, maybe only a “tickle”

-Cough may occur several times per hour to as often as several times a minute

-Must be distinguished from whooping cough (severe attacks of a choking cough that lasts 1-2 minutes often with near vomiting and appearance of suffocation)

-Cough does not seem to get better with time (months or even years)

-All diagnostic studies have come back normal

-Endoscopy of the throat and voice box is normal (to ensure there is no anatomic reason for the cough such as an elongated uvula or large tonsils)

If this description sounds like you, you may have a chronic cough due to laryngeal sensory neuropathy (also called sensory neuropathic cough and vagal neuropathy). Essentially, this means that the nerve that provides sensation to the voice box and is responsible for triggering the cough reflex has been injured, usually by a virus. When this happens, the nerve becomes hyper-sensitive.

Normally, the nerve recovers its normal level of sensitivity and the cough resolves. However, in some patients, the nerve does not recover and a persistent chronic cough results. In this scenario, the best medications are those that “calm” down the nerve. For a given patient, one medication may work better than the other, which may not work at all. Trial and error is unfortunately necessary. With careful guidance with these medications, the cough significantly improves and even completely resolves.

It is becoming recognized that voice therapy under guidance from a qualified speech-language pathologist, is beneficial for patients with neurogenic chronic cough. Through self-awareness exercises and therapy, patients are often able to decrease laryngeal sensory hyper-responsiveness leading to cough decrease. The therapy includes behavior modification, cough suppression behavior and vocal hygiene training.