Chronic Unexplained Cough And Gastroesophageal Reflux Disease: A Quick Clinical Review
R Makkar, G Sachdev
chronic cough, gastroesophageal reflux
R Makkar, G Sachdev. Chronic Unexplained Cough And Gastroesophageal Reflux Disease: A Quick Clinical Review. The Internet Journal of Internal Medicine. 2002 Volume 4 Number 1.
Chronic cough may be caused or triggered by gastroesophageal reflux disease (GERD), which is the third most common cause of chronic unexplained cough after bronchial asthma and postnasal drip. Many patients with unexplained cough have underlying GERD without the classic reflux symptoms making clinicians unaware that GERD may be playing a crucial role in these patients. Aggressive therapy of GERD results in resolution of cough in almost 80 to 95% of patients with GERD associated cough. This short review attempts to describe the underlying mechanisms, diagnostic evaluation and the current management of GERD related cough in the general practice.
The prevalence of GERD associated cough ranges between 10 to 40% depending on the patient population, type of diagnostic test used and whether more than one etiology of cough is ascertained. GERD is found to be the cause of chronic cough in up to 10% of patients when the diagnosis of reflux is made by history, endoscopy or barium esophagogram 1. Adding 24 hour esophageal pH testing in the diagnostic armamentarium, GERD can account for chronic cough in up to 40% of patients 3.
In children the prevalence of GERD as a cause of chronic cough is reported to be 4 to 15% 4, 5.
Pathogenesis Of Cough Associated With GERD
There are two proposed mechanisms of GERD associated cough:
Acid in the distal esophagus stimulating a vagally mediated esophagealtracheobronchial cough reflex
Micro or macroaspiration of esophageal contents into the larynx and tracheobronchial tree
Ing et al6 proposed that gastroesophageal reflux causes cough through an
The Cough Reflux Self Perpetuating Cycle
According to this mechanism, cough from any cause may precipitate further reflux 10, 11. It has been speculated that chronic cough from any cause may trigger swallow related lower esophageal sphincter (LES) relaxation or transient LES relaxation which on a background of raised trans diaphragmatic pressure may lead to reflux 10, 12. The clinical significance of the cough reflux cycle is that management of both cough and reflux needs to be directed at breaking this cycle.
Symptoms In Patients Of GERD Related Cough
Since GERD related cough is most commonly due to a vagally mediated distal esophagotracheobronchial reflex mechanism, the classical reflux symptoms like heartburn, acid regurgitation, water brash etc. are unusual in such patients. Instead, cough may be the sole presenting manifestation of GERD and it can be clinically silent in up to 50 to 75% of the patients 13. Cough that gets worsened after heavy meals or with foods that decrease LES pressure (chocolates, caffeine, peppermint, alcohol, high fat foods) can be due to underlying GERD. Other clues that can point towards underlying GERD as the cause of chronic unexplained cough are hoarseness especially in the morning, nocturnal cough, or cough which gets aggravated after lying down or exercise.
In patients with microaspiration, gastrointestinal symptoms of GERD are more prominent and may predate the onset of cough. Patients with pulmonary macroaspiration syndromes may present with cough in association with other symptoms such as purulent sputum, wheeze, dyspnoea, hemoptysis, chest pain, nocturnal fever, night sweats, and dysphagia with prominent GERD symptoms such as heartburn, waterbrash and oral regurgitation 14.
Patients with chronic cough should have a history and physical examination targeted at the most common causes of cough (asthma, sinusitis, GERD, angiotensin converting enzyme inhibitors use) as well as a chest radiograph. GERD should be considered if there are typical gastrointestinal symptoms or if cough remains unexplained after standard investigations. If heartburn and/ or acid regurgitation are present, no further testing is required before starting medical antireflux therapy. The diagnosis of GERD as the cause of cough can only be made with certainty when cough goes away with specific antireflux therapy. Empirical medical therapy targeted towards reducing reflux is justified in such patients and is more cost effective than testing followed by treatment 15. The diagnostic evaluation of patients with GERD related cough may include a barium study, esophageal endoscopy and esophageal manometry but the initial investigation of choice to assess GERD is 24 hour ambulatory dual probe esophageal pH monitoring, which has a sensitivity and specificity approaching 95% 16. Infact, intraesophageal pH monitoring may the only method of diagnosing GERD in up to 32% patients with cough 17. 24 hour esophageal pH testing should be performed in patients in whom cough is still yet unexplained even after a detailed history and physical examination, chest X ray, pre and post bronchodilation spirometry, upper airway examination, laryngoscopy and paranasal imaging 18.
Management Of GERD Related Cough
Aggressive therapy of GERD results in resolution of cough in almost 80 to 95% of patients with GERD associated cough, although an optimal therapeutic regimen has not been investigated. Irwin17 recommends that all patients be placed on high protein, low fat diet, avoid large meals, omit acidy / spicy foods and beverages, avoid foods that decrease LES pressure (chocolates, caffeine, alcohol), limit eating or drinking between meals and sleep with raised head end of the bed.
Antireflux surgery including Nissen Fundoplication (open or laparoscopic) for patients of GERD related cough is generally reserved for those with proven GERD and who have failed to respond to medical treatment including high dose proton pump inhibitors, or who have recurrence of symptoms after stopping treatment 22, 23. It may also be indicated in patients with continuing micro or gross aspiration (including those with recurrent aspiration pneumonias) who fail to respond to appropriate dietary measures, prokinetic agents and PPI. Clinical symptomatic improvements in patients with cough and aspiration following fundoplication surgery is 45 to 80% with follow up periods of 3 to18 months.
Ravinder PS Makkar, MD D-40, Preet Vihar, New Delhi-110092, India Tel: (0091) (11) 22545183 E mail: email@example.com