Nonallergic rhinitis. Pathophysiology and models for study

Nonallergic rhinitis is a diagnosis of exclusion which is given to patients who suffer perennial nasal congestion, rhinorrhea, and/or sneezing with no identifiable allergic etiology. Because there is still no clear understanding of the pathophysiology, it is possible that a number of different disease processes may be included within this clinically defined entity. This report does not attempt to present an overall discussion of the clinical approaches to patients with nonallergic rhinitis. Instead, an outline is presented of various research approaches which may be used in its study. A number of nasal provocation models using nonallergic stimuli are available for application in the laboratory. These include intranasal methacholine challenges, intranasal histamine challenges, nasal inhalation of cold dry air, and intranasal capsaicin challenges. These models provide certain insights into mechanisms of nonallergic hyper-responsiveness. An additional approach to the study of nonallergic rhinitis is to examine available therapies, allowing the clinician to evaluate various pathways of importance in the disease process. These approaches provide a certain understanding of this common but perplexing entity, although further study is still required.