Post-COVID-19 patients suffer from chemosensory, trigeminal, and salivary dysfunctions

Abstract

Recent literature indicates that post-COVID-19 patients suffer from a plethora of complications, including chemosensory dysfunction. However, little attention has been given to understand the interactions between chemosensory, trigeminal, and salivary dysfunctions in these patients. The aims of this study were (1) to investigate the prevalence and combinations of chemosensory, trigeminal, and salivary dysfunctions, (2) to identify the odorants/tastants that are compromised, and (3) to explore possible associations between the four dysfunctions in post-COVID-19 patients. One hundred post-COVID-19 patients and 76 healthy controls (pre-COVID-19) were included in this cross-sectional, case-controlled study. Participants' smell, taste, trigeminal, and salivary functions were assessed. The patients had a significantly higher prevalence of parosmia (80.0%), hyposmia (42.0%), anosmia (53.0%), dysgeusia (34.0%), complete ageusia (3.0%), specific ageusia (27.0%), dysesthesia (11.0%) and dry mouth (18.0%) compared to controls (0.0% for all parameters, except 27.6% for hyposmia). Complete loss of bitter taste was the most prevalent specific ageusia (66.7%) and coffee was the most common distorted smell (56.4%). Seven different combinations of dysfunction were observed in the patients, the most common being a combination of olfactory and gustatory dysfunction (48.0%). These findings indicate that post-COVID-19 patients experience a range of chemosensory, trigeminal, and salivary disturbances, occurring in various combinations.

Keywords: Burning mouth; Dry mouth; Long COVID; Parosmia; Post-COVID-19; Smell; Taste.

Figure 1

Boxplots illustrating (A) VAS self-reported smell score and (B) VAS self-reported taste score, in post-COVID-19 patients and controls. Mann–Whitney U test, ***p < 0.001. The circles in the figure represent outliers.

Figure 2

Histogram illustrating (A) smell diagnosis and (B) taste diagnosis, in post-COVID-19 patients and controls. Fisher’s exact test, ***p < 0.001.

Figure 3

Histogram illustrating self-reported parosmia, dysgeusia, dysesthesia and xerostomia in post-COVID-19 patients.

Figure 4

Pie chart showing distribution of patients with different combinations of dysfunctions (a–g).

Figure 5

Scatter plots illustrating correlations between (A) VAS self-reported smell score and Sniffin' Sticks score (r = 0.5), (B) VAS self-reported smell score and VAS self-reported taste score (r = 0.6), and (C) VAS self-reported taste score and Taste Strips score (r = 0.06), Pearson's correlation coefficient test.