Coughing is the body's reflexive response when something irritates the lungs or air passages (including the nasopharynx, oral parts, throat, larynx and upper esophagus). This reflex causes the relevant body part to forcibly expel the irritation or unwanted particles from the air passages.

• Common causes of chronic cough include:
• Chronic infections such as sinusitis, tonsillitis, pharyngitis, laryngitis, bronchitis, chest infections and dental infections, where sticky mucous and inflammation of the throat irritate the air passages. The sticky mucous may also be inhaled into the lungs. Coughing is the reflex to expel this mucous.
• Smoking (which may constantly irritate the air passages)
• Cancer of the throat, oral cavity, lungs or esophagus.
• Medication - certain antihypertensive medication such as Ace inhibitors (note, in particular, medication with names ending with "pril")
• Allergy - allergic rhinitis, throat allergy, cough variant asthma and asthma
• Laryngopharyngeal Reflux (LPR)

What is LARYNGOPHARYNGEAL REFLUX (LPR)?

LPR is a fairly common condition, though often undiagnosed. The throat and larynx serve as a passage way, not only for air to go to the lungs, but also for food to reach the stomach, via the esophagus.

Not uncommonly, the contents of the stomach can regurgitate back into the esophagus, and can sometimes reach the upper esophagus and larynx. This form of involuntary regurgitation is known as LPR.

The regurgitated stomach content would include stomach acids, which could burn the sensitive larynx and irritate it, thus causing coughing. LPR often leads to inflammation or ulcerations in the back of the larynx, where the larynx meets the upper esophagus. LPR is also known to reach the nasopharynx. If LPR reaches the Eustachian tubes (which links the nasopharynx to the ears), it can cause otitis media (middle ear infection).

During the night, while the patient lies horizontally, the stomach content may make its way up the esophagus to the back of the throat and collect there. Patients are often awoken by their own coughing, or wake up in the morning complaining of throat discomfort.

LPR (even a mild case) may exacerbate the severity of an existing cough.

Diagnosis of LPR

The majority of LPR sufferers may have no symptoms of gastric pain or heartburn. Examination of the gastric system or barium swallow X-ray may show no abnormality.

Video endoscopic equipment can be used to examine the back of the larynx where it meets the esophagus. LPR may be indicated if there is redness, swelling, inflammation, polyp, ulceration or granulation in this area.

The only study presently available to positively diagnose LPR involves the insertion of a pH (acidity) catheter through the nose to the esophagus. The catheter is left for 24 hours to monitor the pH levels, during normal day and night activities. However, due to the inconvenience and high cost of performing this procedure, it is not often done.

Generally, LPR is diagnosed by actually treating the problem! A patient suspected of having LPR would often be treated with medication to lower gastric acid levels and would be advised to make lifestyle changes to reduce LPR, such as:

• Avoidance of stress (which increases gastric acidity)
• Avoidance of heavy meals
• To take smaller and more frequent meals
• To wear loose clothing
• To reduce weight (as obesity increases LPR)
• To avoid sleeping on a full stomach (preferably do not eat or drink 3-4 hours before going to bed)
• To sleep with the head of the bed elevated by 20-30º

If the above medication and lifestyle changes alleviate the patient's chronic cough, LPR is usually diagnosed as the likely cause of the cough.