Modified Olfactory Training Is an Effective Treatment Method for COVID-19 Induced Parosmia

Abstract

Objectives: Coronavirus disease (COVID-19) infection often causes olfactory dysfunction and parosmia may occur in some patients with olfactory dysfunction. In this study, we retrospectively investigated the effectiveness of modified olfactory training (MOT) for the treatment of COVID-19-induced parosmia.

Study design: This study presents results of MOT performed with 12 odors for 36 weeks in patients with olfactory dysfunction following COVID-19 infection. A total of 75 participants were included in the study (mean age 33 years, range 16-60 years).

Methods: The patients were separated into two groups: 1) Treatment group consisted of parosmia patients who received MOT with three sets of four different odors sequentially. 2) Control group consisted of parosmia patients who did not perform any olfactory training. Both groups were matched for age and sex distribution of participants. TDI scores were compared at the time of application and at the end of the 9th month by the Sniffin' Sticks Test. The results of the 0th and 9th months were recorded by applying the parosmia assessment scale to both groups. The results were analyzed statistically, and p < 0.05 was considered significant.

Results: When the treatment group and the control group were compared, a significant improvement was observed in both groups at the third, sixth, and ninth month, however the improvement in the treatment group was found to be better than in the control group (P < .001). Extending the treatment from 6 to 9 months in the treatment group was found to be effective in mitigating parosmia complaints and improving discrimination scores (P < .001).

Conclusion: This study has shown that modified olfactory training is effective in the treatment of parosmia following COVID-19 infection.

Level of evidence: 3 Laryngoscope, 132:1433-1438, 2022.

Keywords: COVID-19; Parosmia; modified olfactory training; olfactory dysfunction.

Fig. 1

Planning of the modified olfactory training method: Olfactory training consisted of smelling of the scents for 10 seconds alternately by leaving 10 second intervals between different scents. The training was applied for 5 minutes twice a day.

Fig. 2

Changes in parosmia scores at 0, 3, 6, and 9 months for each individual in the treatment group. (Parosmia is quantified in 3 degrees (0–1 point) with these factors: frequency of occurrence: daily = 1 point, otherwise = 0 points, intensity: very strong = 1 point, otherwise = 0 points, social effects (e.g., weight loss, significant change of habits): yes = 1 point, no = 0 points. The summary score represents the degree of the disorder.) There are minimal changes between 0 and 6 months, however; changes in parosmia score between 6‐ and 9‐months are more evident.

Fig. 3

TDI scores of treatment and control groups between 0 and 9 months. While there was no significant difference between the two groups at the beginning (P = .462), there was a significant improvement in the treatment group at the end of the 9th month (P < .001). D = discrimination; I = identification; MOT = modified olfactory training; T = thresholds.

Fig. 4

TDI scores of the control group between 0 and 9 months. D = discrimination; I = identification; T = thresholds.

Fig. 5

TDI scores of the treatment group between 0 and 9 months. D = discrimination; I = identification; T = thresholds.