NONINFECTIOUS, NONALLERGIC RHINITIS (NINAR) - CONSIDERATIONS ON POSSIBLE MECHANISMS

Most patients who suffer from chronic noninfectious, non-allergic rhin itis (NINAR) cannot be assigned to a syndrome of known etiology. The s ymptomatology may well resemble that of allergic rhinitis; however, NI NAR has lower prevalence of sneezing conjunctival symptoms and pruritu s and higher prevalence of symptoms compatible with sinus disease. The triggers far the symptoms of NINAR are mainly irritants and changes i n atmospheric conditions. Among individuals who develop chronic rhinit is symptoms, the percentage of nonallergic etiology increases steadily with age and is more than 60% beyond the fifth decade of life. Our st rategy regarding the pathophysiology of NINAR should be to identify fu nctional abnormalities of nasal mucosa that can potentially result in the alleged nasal symptoms. In this respect, comparison of patients wi th NINAR to patients with allergic rhinitis and to healthy individuals could shed light into the cause(s) of NINAR. Three potential function al abnormalities are discussed in this article: those associated with the aging process of the nasal mucosa, those resulting in various form s of nasal hyperreactivity, and those reflecting imbalanced neuronal c ontrol of end organs of the nose. The most interesting development in the therapy of NINAR is the use of capsaicin. Although placebo-control led studies are scarce and participants have not been adequately chara cterized, it is possible that abnormal nociceptor nerve endings play a role in the generation of the symptoms of NINAR. Alternatively, NINAR may represent a condition of increased perceptual acuity to irritants and to environmental changes. This problem may also benefit from defu nctionalization of nociceptors.