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Chronic cough, defined as coughing that lasts for more than three weeks in the absence of other cold or allergy symptoms, is a major problem for the people who can't stop coughing and the healthcare system at large. Each year, more than 30 million people in the U.S. seek medical care for chronic cough, with treatment costs in the tens of billions of dollars.

Coughing is actually a defense mechanism to clear our airways. It plays an important role in maintaining our health and protecting our lungs. We cough to expel foreign material such as food or to remove secretions. We also cough when there is too much or too little moisture in the air, when we have inflammation of the sinuses, nose and lungs, or in response to irritants such as chemicals.

When a cough is strong and continual, however, it can actually result in physical damage to the body. It can cause a hernia, urinary incontinence, broken blood vessels in the eyes and skin, a hemorrhage in the voice box, spitting up blood, exhaustion and fatigue, and even rib fractures. People who have a chronic cough may also suffer from sleep disturbances.

In addition to the physical problems, there are also social problems that arise from chronic coughing. Some people with a chronic cough may withdraw from social situations and avoid group functions, entertainment venues or restaurants. Chronic coughers are sometimes avoided by people who think the cough is associated with an illness that they could catch.

Acute Cough
An acute cough is one that has been present for less than three weeks. It is most often associated with the common cold, which is caused by a virus. As the cold improves, so does the cough. Drinking more fluids, adding moisture to the air, taking cough medicine, and resting the voice typically help decrease the symptoms. However, when coughing persists even after other cold symptoms have subsided, or if you develop a persistent cough that is not associated with a cold, other causes must be considered.

Causes of Chronic Cough
The most commonly diagnosed causes of chronic cough are allergy, asthma, bronchitis, and post-nasal drip. These conditions are often the initial cause of a cough but if the cough continues for more than three weeks after the infection or condition has ended, it is considered "chronic."

Symptoms of an allergy typically include itchy eyes and throat, sneezing, runny nose and eyes, and coughing. These symptoms respond quickly and effectively to antihistamines and nasal steroid sprays.

Asthma, a breathing disorder, is frequently associated with wheezing and shortness of breath. Coughing can be a component of asthma but is usually not an isolated symptom. Asthma should respond to various inhalers.

Bronchitis can be associated with acute coughing but is typically accompanied with other respiratory symptoms such as fatigue, slight fever and chills, chest discomfort and mucus that is clear, white, yellowish gray or green. These symptoms typically resolve with treatment.

Post-nasal drip is not a disease. It is the result of mucus draining from our sinuses into our throats. Technically, every human being has post-nasal drip, since the body typically produces up to two

liters of mucus a day. The purpose of mucus is to protect against pollutants and aid in swallowing. In the nose, mucus helps filter the air we breathe, trapping bacteria, dust, smoke and other pollutants and preventing them from entering our body. When fighting off a cold, sinus infection or allergy, the glands in our sinuses produce extra mucus. This increases post-nasal drip, which is usually accompanied by symptoms generally associated with these illnesses such as facial pain, pressure, sneezing, itchy eyes, nasal blockage, and headache. Sometimes the throat becomes more sensitive due to changes in its lining or sensory nerves. This may lead to greater awareness of post-nasal drip; but if there are no allergy, respiratory or sinus infection symptoms, the increased sensitivity is not an indication of illness.

Although there are other causes of chronic coughing, such as cough induced by medications, vocal fold paralysis, swallowing problems, esophageal pockets, and rare neurological disorders, there are two causes that are often overlooked and misdiagnosed: Laryngopharyngeal reflux (LPR) and laryngeal sensory neuropathy, also known as vagal neuropathy (VN).

Laryngopharyngeal Reflux (LPR)
LPR is reflux of stomach contents, including acid and digestive enzymes, into the throat, which causes irritation and inflammation. Acidic foods and drinks can activate those digestive enzymes, leading to repeat irritation and chronic changes of the throat structures. Symptoms of LPR include:
• constant throat clearing
• sensation of a lump in the throat
• changes in the voice
• sour taste or burning in the throat
• difficulty swallowing
• post-nasal drip sensation
• coughing, especially chronic, during the night or in the morning

LPR is diagnosed by reviewing the symptoms and examining the voice box and throat. Sometimes the acid level in the throat will be measured. Since diet is the principal cause of LPR, treatment focuses on educating patients about what types of foods are most beneficial and which foods should be avoided. For severe or long-lasting cases of LPR, medications may be prescribed to help suppress acid secretion.

LPR should not be confused with gastroesophageal reflux disease (GERD). LPR most commonly occurs without GERD symptoms, which include heartburn, regurgitation, belching, abdominal discomfort and bloating.

Vagal Neuropathy
A vagal neuropathy (VN), which typically follows a viral upper respiratory illness, is an irritation of the nerves in the throat that sends sensations to the brain. The irritated nerves may lead to chronic, recurrent coughing. This kind of cough, which frequently occurs in spasms, is often preceded by a tickle sensation in the throat. Coughing that is a result of vagal neuropathy can be associated with runny nose or eyes, changes in voice, and trouble breathing (noisy breathing when trying to inhale). Many people with vagal neuropathy report that their coughing episodes can be set off by certain stimuli, such as talking, laughing, perfumes or other odors, cold, dry or moist air, or by physically touching or moving their neck.

Diagnosis of vagal neuropathy involves examination of the voice box and may include measurement of acid levels in the throat. In addition, electromyography (EMG), a test of the voice box muscles that can measure whether there is any nerve damage, may be performed. Vagal neuropathy is treated with medications that help suppress the urge to cough. In addition, a speech pathologist may perform a special type of breathing therapy that helps the person stop coughing by allowing the brain to suppress the cough when the stimulation occurs.

If you or someone you know has been having a chronic cough for weeks, months, or even years, an examination by a laryngologist (an ENT specializing in throat disorders) can help determine the cause of the cough, especially if the cough is present without the other symptoms associated with allergy, asthma, sinus disease, post-nasal drip, or bronchitis.

 

Craig H. Zalvan, MD, the medical director of the Institute for Voice and Swallowing Disorders at Phelps, is a board-certified otolaryngologist (ear, nose and throat physician) who completed a specialty fellowship in laryngology, which focuses on voice and swallowing disorders. For more information about the diagnosis and treatment of coughing problems, call the Institute for Voice and Swallowing Disorders at 914-366-3636.