xRead - Globus and Chronic Cough (April 2024)

349

Altman and Irwin

Rhinologic

Sinusitis

Allergic Rhinitis

Systemic Disease

Non-Allergic Rhinitis

Neurologic

Unified Airway

Tumor

Chronic Cough

GERD/LPR

Aspiration, Reflex

(silent)

Asthma

Esophageal

Other Inflammatory

Pulmonary Infection

Pulmonary

Figure 1. Flow diagram showing the different contributing factors to chronic cough and their relationships. GERD, gastroesophageal reflux disease; LPR, laryngopharyngeal reflux.

complex interplay of aerodigestive diseases is ripe for collabora tion in clinical and basic science research. We summarize the different disease contributions to chronic cough in Figure 1 , showing some relationships of how they interrelate. This figure is actually very complex because the spectrum of clinical disease is broad, and each of these diseases often exacerbates one another. Factors Contributing to Chronic Cough Rhinologic diseases are well known to cause chronic cough, especially in the pediatric population. We know that allergic postnasal drip has an irritant effect on the palate and pharynx. Allergic and nonallergic inflammation in the nose may result in obstruction of the paranasal sinuses, leading to postobstructive infectious drainage. Environmental and occupational irritants also induce inflammation that may affect mucus secretions and exacerbate the mechanical obstruction. Topical mucosal immu nity is affected by all of these processes. Pulmonary diseases have a similar set of relationships between infectious, asthmatic, and nonasthmatic inflammatory disease. Probably the most common nonasthmatic cause of cough is cigarette smoking, which results in ciliary dysfunction, mucus

stasis, and direct cough receptor stimulation. The distinction between chronic bronchitis, bronchiolitis, and bronchiectasis in the presence of emphysema and asthmatic exacerbation of these diseases may be challenging. Furthermore, the effects of inhalers used to treat pulmonary disease may also cause cough due to sicca, irritation from the drug or dispersant, or Candida over growth in the larynx. The unified airway is integral to our understanding of cough. 6 Emerging evidence now supports our long-held obser vation that upper and lower airway diseases are closely related and that allergy plays an important role in triggering both upper and lower airway disease. Baseline asthma is exacer bated during allergic exposures that are primarily encountered in the nose, as well as during a sinus infection that may spread to cause bronchitis. In addition, more aggressive management of chronic sinusitis tends to improve overall asthma scores in patients with both diseases. Mucus trafficking between the upper and lower airways is integral to the concept of the uni fied airway, but neurologic reflexes, the immune system, and neurogenic mediators may also play roles. There is also evi dence to support a sinonasal-bronchial reflex, as many otolar yngologists have observed patients cough during nasal