Clinical study of persistent olfactory and gustatory dysfunctions in COVID-19 patients

• Published in: Stomato-pharyngology Vol. 36; no. 2; pp. 178 - 185
• Main Authors: Otachi, Takae, Nin, Tomomi, Fushimi, Katsuya, Tsuzuki, Kenzo
• Format: Journal Article
• Language: Japanese
• Published: Japan Society of Stomato-pharyngology 2023
• Subjects: COVID-19; gustatory disorder; olfactory disorder
• DOI: 10.14821/stomatopharyngology.36.178
• ISSN: 0917-5105

Although there are various reports on the clinical manifestations and frequency of olfactory and taste disorders after COVID-19, the olfactory and taste functions of patients had not been assessed, nor do the authors of most reports follow the long-term course of the disease. In this study, we aimed to evaluate symptoms, virus strains expected from the time of infection, duration of illness, results of olfactory and gustatory tests, association between olfactory and gustatory sensation, and outcome 6 months after the initial visit. Seventy-seven patients （32 men and 45 women, aged 6-65 years） who complained of smell and taste disorders after COVID-19 and who visited our clinic from January 2021 to October 2022 were included in the study. The subjective olfactory and taste changes were assessed using the visual analog scale （VAS）. A standard olfactometry （T＆T olfactometer） and intravenous olfaction test were used to assess olfactory function, and a filter paper disk and an electrogustometer were used to assess taste function. The most common complaint was both olfactory and gustatory impairment （49％）. The highest number of patients （48％） was seen during the Delta variant epidemic. The median duration of illness was 4 months. In 38 patients who complained of both olfactory and gustatory impairment, there was a correlation between olfactory and gustatory symptoms in terms of type, severity, and test results. Of 63％ patients, the results of taste examination were assessed as normal, indicating the cause was olfactory dysfunction. In total, 79％ of the patients were finally diagnosed as having olfactory dysfunction. After 6 months of follow-up, 68％ of the patients with taste impairment and 61％ of those with olfactory impairment showed improvement. It is important to evaluate olfactory and gustatory function by not only symptoms but also examinations in order to understand the status of COVID-19 patients.