Characteristics of laryngeal symptoms induced in patients with allergic rhinitis in an environmental challenge chamber.

Background: People with allergic rhinitis often have laryngeal symptoms (LSs) in addition to nasal symptoms during the pollen-scattering season.

Objective: To clarify the characteristics of the LSs induced by pollen exposure using an environmental challenge chamber.

Methods: Cypress pollen exposure using an environmental challenge chamber for 25 participants with cypress pollen-induced allergic rhinitis was performed for 3 hours for 2 consecutive days in 3 study courses: namely, pollen exposure under normal nasal breathing and pollen or sham pollen exposure with nasal blockage, which eliminated any allergic reactions in the nasal mucosa. The nasal and LSs scores and the levels of serum inflammatory mediators, including eosinophil cationic protein (ECP), were monitored. Laryngeal examinations and physiologic lung tests were also conducted.

Results: Various LSs were reported, and these LSs were significantly elevated during pollen exposure and even under sham exposure with artificial nasal blockage. The pollen exposure with artificial nasal blockage exaggerated the LSs in 32% of the participants and also increased the serum ECP levels. The serum ECP levels did not change after sham exposure. The findings of both laryngeal examinations and lung tests failed to reveal any significant changes.

Conclusion: Nasal obstruction could induce significant LSs even without pollen exposure. LSs were enhanced by pollen exposure and allergic reactions in the larynx could thus be involved in this enhancement.

Trial Registration: clinicaltrials.gov Identifier: UMIN000015667.