I. Executive Summary: Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document.Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided.Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS.

Background: Cilia are complex and powerful cellular structures of the respiratory mucosa that play a critical role in airway defense. Respiratory epithelium is lined with cilia that perform an integrated and coordinated mechanism called mucociliary clearance. Mucociliary clearance is the process by which cilia transport the mucus blanket overlying respiratory mucosa to the gastrointestinal tract for ingestion. It is the primary means by which the airway clears pathogens, allergens, debris, and toxins. The complex structure and regulatory mechanisms that dictate the form and function of normal cilia are not entirely understood, but it is clear that ciliary dysfunction results in impaired respiratory defense. Methods: A literature review of the current knowledge of cilia dysfunction in chronic rhinosinsusitis was conducted. Results: Ciliary dysfunction may be primary, the result of genetic mutations resulting in abnormal cilia structure, or, more commonly, secondary, the result of environmental, infectious, or inflammatory stimuli that disrupt normal motility or coordination. Patients with chronic rhinosinusitis (CRS) have been found to have impaired mucociliary clearance. Many biochemical, environmental, and mechanical stimuli have been shown to influence ciliary beat frequency, and common microbial pathogens of respiratory mucosa such as Pseudomonas aeruginosa and Haemophilus influenzae have developed toxins that appear to interrupt normal mucociliary function. Furthermore, inflammatory mediators known to be present in patients with CRS appear to impair secondarily mucociliary clearance. Conclusion: The goal of this article is to summarize the recent developments in the understanding of cilia dysfunction and mucociliary clearance in CRS.

Olfactory dysfunction is a cardinal symptom of chronic rhinosinusitis (CRS), a disease that affects 12.5% of the adult population across all racial and ethnic groups.^1,2 The prevalence of olfactory dysfunction in CRS ranges from 30% to 80%; however, the mechanisms by which olfactory loss occurs are not always clear.^3,4 Some patients have significant nasal obstruction and impaired airflow into the olfactory cleft due to polyps or edematous mucosa. Other patients have olfactory loss but without obvious airflow restriction, suggesting additional mechanisms may also be contributory.