Persisting olfactory dysfunction in post-COVID-19 is associated with gustatory impairment: Results from chemosensitive testing eight months after the acute infection

Abstract

Olfactory and gustatory disorders are prominent symptoms of acute COVID-19. Although both senses recover in many patients within weeks to months, persistency has been described in up to 60%. However up to now most reports on the course of chemosensitive disorders after COVID-19 are not based on psychophysical testing but only on subjective patients’ ratings. In this study we assessed both olfaction and gustation using psychophysical tests eight months after COVID-19. Validated psychophysical testing revealed hyposmia in 18% and hypogeusia in even 32% of 303 included patients. This shows that olfactory and especially gustatory disorders have to be seen as important chronic symptoms post-COVID-19. The high prevalence of gustatory dysfunction indicates that gustatory function does not recover or might even deteriorate in the months following the acute infection.

Assessment of Smell and Taste Disturbances among COVID-19 Convalescent Patients: A Cross-Sectional Study in Armenia

“…Since our study participants came for investigation after disease diagnosis at different time intervals, we expected their quantitative and qualitative characteristics would be different because of the time interval. We decided to conduct a study to evaluate neurosensory disturbances with respect to time because several studies observed that, if COVID-associated olfactory and gustatory disturbances were not improved within the first two weeks of recovery, they will persist for a long period [ 26 , 44 , 45 ]. Also, a scientific experiment found that the anatomical and functional recovery of the olfactory epithelium takes about 45 days [ 46 ] and odor perception takes about 90 days to recover [ 47 ].…”

“…Smell sensation is mainly perceived through two cranial nerves, that is, the olfactory and the trigeminal nerves [ 26 , 27 , 28 ]. It has been found that a majority of fragrances are recognized by both the nerves; however, there are a few orders specifically perceived by the olfactory or the trigeminal nerve [ 29 ].…”

“…It has been found that a majority of fragrances are recognized by both the nerves; however, there are a few orders specifically perceived by the olfactory or the trigeminal nerve [ 29 ]. For instance, the olfactory receptor neuron (mOR-EG), has been found to be triggered by eugenol containing essential oils such as clove oils [ 3 , 24 , 30 ] and the trigeminal receptor neuron (TRPV3), has been found to identify the odor of camphor spirit as temperature [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. In addition to that, eugenol is also found to be a pure olfactory or a non-trigeminal stimulus [ 34 ].…”

Author’s reply to the Letter to the Editor “The study of olfactory dysfunction in SARS-CoV-2 variants”

“…Chemosensitive assessment is normally performed in specialized departments and comprises the collection of the patient's history, a clinical examination including nasal endoscopy and psychophysical testing. As SARS-CoV-2 positive patients are normally quarantined, home-based approaches have been established using self-prepared or shipped test kits combined with questionnaires [4,5], online surveys [6], or telephone interviews [7]. I.…”

Relación entre las alteraciones del sentido del gusto y/o el olfato y el síndrome post-covid

“…Por otro lado, según un estudio, aproximadamente el 25% de los pacientes estudiados presentaba deficiencias quimiosensoriales a los 8 meses, la cual se manifestaba con alteraciones gustativas y olfativas crónicas 14 .…”