Damage of the pharyngeal mucosa and hyperresponsiveness of airway in sinusitis

In sinusitis bronchoconstriction is supposed to originate from pharyngobronchial reflexes triggered by seeding of the inflammatory process into the pharynx.

Our aim was to evaluate whether in sinusitis bronchial and extrathoracic airway (EA) dysfunction correlate with morphologic abnormalities of the pharyngeal mucosa.

We performed histamine inhalation challenge, nasal lavage, and nasopharyngeal biopsies in 24 nonasthmatic patients with exacerbation of chronic sinusitis. The histamine PC20 was the threshold of bronchial responsiveness, and that causing 25% fall in maximal midinspiratory flow was the threshold of EA responsiveness (PC25MIF50). Thresholds of 8 mg/ml or less were assumed to indicate bronchial hyperresponsiveness (BHR) or EA hyperresponsiveness (EAHR). PC20 and PC25MIF50 values were related to clinical data, nasal lavage fluid eosinophils, pharyngeal epithelium and basement membrane thickness, and density of submucosal vessels and nervous fibers.

The PC20 was closely related to PC25MIF50 (p = 0.0004). Ten patients had EAHR, 9 had combined EAHR and BHR, and 5 had neither EAHR nor BHR. EAHR was strongly associated with epithelial thinning, and BHR with long-standing sinusitis, a lower PC25MIF50, increased submucosal nerve density and increased nasal lavage fluid eosinophils.

Our findings suggest that in nonasthmatic patients with sinusitis, pharyngeal damage may contribute to airway dysfunction by favoring the access of irritants to submucosal nerve endings, with activation of constrictive reflexes to the EA. Proliferation of sensory neurons, consequent to long-lasting pharyngeal inflammation, may cause more severe EA narrowing and activate pharyngobronchial reflexes.