Post nasal drip syndrome (PNDS), gastro-oesophageal reflux (GOR) and asthma form the pathogenic triad of chronic cough. If the cough is ascribed to more than one factor, the pathogenic triad is used for complete diagnosis. If a non-smoker is suffering from chronic cough, but the patient’s chest radiograph is normal and patient is not administered angiotensin-converting enzyme (ACE) inhibitors, one of the triad conditions may be causing the cough.
PNDS-induced cough
Diseases affecting paranasal sinuses, pharynx and nasal fossae cause post nasal drip syndrome. For example, chronic and / or acute sinusitis, rhinitis because of medication or environmental irritants, post infectious rhinitis, vasomotor rhinitis, allergic rhinitis, common cold or other upper respiratory tract disorders may cause PNDS. Since these upper respiratory tract conditions have some common symptoms, the diseases are collectively referred to as rhinosinusitis.
Various scientific studies concluded that the post nasal drip syndrome is one of the common causes of chronic cough, especially in patients who do not smoke. The number of PNDS incidences is high in the US as compared to that recorded in the European countries.
Since there are no distinct characteristics (pathognomonic) of PNDS, a number of factors are taken into account to diagnose the disease. For instance, interpretation of radiographic material, physical examination, symptoms and effect of the selected PNDS therapy are studied simultaneously for the diagnosis. The response to the therapy is considered as the most suitable diagnosis technique. A sinus coronal CT scan, 4-view sinus radiograph and nasolaryngoscopy may also be useful in the diagnosis.
Mechanical or chemical irritation of pharynx and / or larynx receptors may cause cough in the patients suffering from PNDS. When endpoints of pharyngeal branch nerve are stimulated, cough occurs in the upper respiratory system.
The patients suffering from PNDS-induced cough may have mucus in oropharynx, oropharyngeal mucosa resembling a cobblestone, nasal discharge and strong desire to clean throat frequently.
Nasal steroids, nasal cromolyn and oral antihistamines are effective in case of allergic rhinitis-induced PNDS. A saline nasal wash is also helpful.
Cough because of GOR
Gastro-oesophageal reflux (GOR) is also known as gastrooesophageal reflux disease (GERD). A number of patients having cough may have regurgitation, heartburn, sour taste and other gastrointestinal (GI) symptoms. If reflux is high, dyspnea, wheezing, purulent sputum or other pulmonary symptoms may occur. Patients may also complaint about hoarseness and sore throat, laryngeal disorders.
Asthma related cough is difficult to diagnose due to minimum wheezing or breathlessness. Atypical or bacterial bronchitis or a viral respiratory disorder may cause the cough in asthma patients. This nonproductive cough occurs during night and day.
