Autonomic reflexes and non-allergic rhinitis

Functions traditionally ascribed to the nose include warming, humidification, and filtration of inspired air prior to its passage to the lower respiratory tract. The nose thus conditions inspired air, making it suitable for pulmonary gas exchange. In order to carry out these functions, the nose is subject to a complex series of reflexes mediated via the autonomic nervous system. The effector tissues are the nasal blood vessels and glands. Perennial non-allergic rhinitis may be divided into two types based on the presence or absence of eosinophilia in nasal secretions. Much circumstantial evidence suggests that non-eosinophilic non-allergic rhinitis (NENAR) may be a disease of autonomic imbalance. In a series of studies carried out at the University of Liverpool, patients with perennial non-allergic rhinitis, and NENAR in particular, were found to have qualitative and quantitative abnormalities in their nasal response to various stimuli as manifested by changes in nasal patency. The nasal response to axillary pressure is much reduced in NENAR patients compared with normal controls, and the normal decrease in nasal resistance in response to standing is abrogated. Isometric exercise has little effect in normal subjects, but those with NENAR demonstrate an increase in nasal resistance. A similar effect is seen in response to the cold presser test. Of great importance for therapy is the effect of topical fluticasone propionate in patients with NENAR. Treatment normalizes the damaged nasal reflexes seen in this condition, whereas placebo has no effect. However, abnormalities in other non-nasal autonomic reflexes (systemic parameters) are not affected by treatment.