IntroductionCOVID-19 induces both acute and chronic neurological changes. Existing evidence suggests that chemosensory changes, particularly olfactory loss, may reflect central neurological dysfunction in neurodegenerative diseases and mark progression from mild cognitive impairment to Alzheimer’s. This scoping review summarizes the available literature to evaluate the relationship between neurocognition and olfaction in young to middle-aged adults with minimal comorbidities following COVID-19 infection.MethodsA literature search of PubMed, Ovid Embase, Web of Science, and Cochrane Library was conducted. Studies underwent title/abstract and full text screening by two reviewers, with a third reviewer resolving any conflicts. Remaining studies underwent data extraction.ResultsSeventeen studies were eligible for data extraction after the review process, where 12 studies found significantly poorer cognition in those suffering from olfactory dysfunction, four studies showed no association between cognition and olfaction, and one study reported lower anosmia prevalence among patients with cognitive impairment.ConclusionThe majority of studies in this review find that olfactory dysfunction is associated with poorer cognition. More rigorous studies are needed to further elucidate the relationship between olfaction and cognition after COVID-19.

BackgroundRetronasal olfaction (RNO) refers to the perception of odorants inhaled through the mouth and carried through the nasopharynx to olfactory receptors within the olfactory cleft, enabling the perception of flavor. Although orthonasal olfactory dysfunction in chronic rhinosinusitis (CRS) has been widely described, the impact of CRS on RNO is less clear. In this study, we systematically review available literature to provide an update on RNO in the setting of CRS.MethodsWe systematically searched PubMed, Ovid Embase, Web of Science, and the Cochrane Library for studies examining RNO in patients with documented CRS. The primary outcome of interest was objective psychophysical measurement of olfaction, including characterization of RNO.ResultsWe identified 404 unique references that underwent title and abstract review by two independent reviewers, with 52 articles undergoing full-text review, where 10 relevant studies underwent data extraction. Although outcome measures varied, all included studies demonstrated diminished RNO in patients with CRS. Of six studies evaluating the relationship between retronasal and orthonasal olfactory test scores in CRS patients two out of six (33%) demonstrated a correlation between both forms of olfaction and CRS, and two out of six studies (33%) found significantly lower orthonasal olfactory test scores compared to retronasal olfactory test scores. Two of three found significant improvement in RNO with treatment of underlying CRS. Of three studies examining patient reported outcome measures (PROMs) in CRS, two found significant associations between retronasal olfactory test scores and PROMs.ConclusionsBased on the current literature, CRS patients appear to have diminished RNO, which may be associated with orthonasal olfactory dysfunction and decreased quality of life in this population. Higher level of evidence studies are required to further elucidate these relationships and the impact of medical and surgical CRS management on RNO.

BackgroundEustachian tube dysfunction (ETD) may occur distinct from, or in conjunction with, chronic rhinosinusitis (CRS+ETD). Intranasal corticosteroid sprays are often prescribed for ETD, though ET distribution may be limited. To date, no anatomic studies compare nasopharynx (NP) distribution between conventional nasal sprays (NS) and exhalation delivery systems (EDS) after surgery. This study utilizes a cadaver model to examine topical NP delivery using EDS vs. NS before and after targeted endoscopic sinus surgery (ESS).MethodsSixteen sinonasal cavities were administered fluorescein solution via NS and EDS before and after maxillary antrostomy and anterior ethmoidectomy, followed by nasal endoscopy of the NP and ET orifice. Seven blinded experts submitted staining ratings of endoscopy images on a 0‐3 point scale, with ratings averaged for analysis.ResultsInterrater reliability was excellent (intraclass correlation 0.956). EDS was associated with significantly greater NP staining vs. NS in a pooled cohort of nonsurgical and ESS specimens (1.19±0.81 vs. 0.78±1.06, p = 0.043). Using a logistic regression model, EDS significantly outperformed NS in nonsurgical (OR 3.49, 95%CI: 1.21‐10.09, p = 0.021) and post‐ESS (OR 9.00, 95%CI: 1.95‐41.5, p = 0.005) specimens, with greatest relative staining observed for EDS after targeted ESS (OR 18.99, 95%CI: 3.44‐104.85, p = 0.001).ConclusionsEDS is more effective than NS in topical delivery to the NP and ET orifices in cadavers. Targeted ESS may facilitate greater NP penetration by EDS compared to NS, with possible synergism after ESS for augmented delivery. These findings suggest a role for EDS delivery methods for ETD management and in CRS+ETD patients undergoing sinus surgery.This article is protected by copyright. All rights reserved