Olfactory Training in Post-COVID-19 Persistent Olfactory Disorders: Value Normalization for Threshold but Not Identification

(1) Background: Persistent post-viral olfactory disorders (PPVOD) are estimated at 30% of patients one year after COVID-19 infection. No treatment is, to date, significantly effective on PPVOD with the exception of olfactory training (OT). The main objective of this work was to evaluate OT efficiency on post-COVID-19 PPVOD. (2) Methods: Consecutive patients consulting to the ENT department with post-COVID-19 PPVOD were included after completing clinical examination, the complete Sniffin’ Stick Test (TDI), the short version of the Questionnaire of olfactory disorders and the SF-36. Patients were trained to practice a self-olfactory training with a dedicated olfactory training kit twice a day for 6 months before returning to undergo the same assessments. (3) Results: Forty-three patients were included and performed 3.5 months of OT in average. We observed a significant TDI score improvement, increasing from 24.7 (±8.9) before the OT to 30.9 (±9.8) (p < 0.001). Based on normative data, a significant increase in the number of normosmic participants was observed only for the threshold values (p < 0.001). Specific and general olfaction-related quality of life improved after the OT. (4) Conclusions: Olfactory function appeared to improve only in peripheral aspects of post-COVID-19 PPVOD after OT. Future controlled studies must be performed to confirm the OT role and justify new therapeutic strategies that may focus on the central aspects of post-COVID-19 PPVOD.

Correlations between Persistent Olfactory and Semantic Memory Disorders after SARS-CoV-2 Infection

Background: One of the main symptoms of COVID-19 is hyposmia or even anosmia. Olfactory identification is most often affected. In addition, some cognitive disorders tend to appear following the infection, particularly regarding executive functions, attention, and memory. Olfaction, and especially olfactory identification, is related to semantic memory which manages general knowledge about the world. The main objective of this study was to determine whether semantic memory is impaired in case of persistent post COVID-19 olfactory disorders. Methods: 84 patients (average age of 42.8 ± 13.6 years) with post COVID-19 olfactory loss were included after consulting to the ENT department. The clinical evaluation was carried out with the Pyramid and Palm Tree Test, the word-retrieval task from the Grémots, the Sniffin’ Sticks Test and the Computerised Olfactory Test for the Diagnosis of Alzheimer’s Disease. Results: Semantic memory was impaired in 20% (n = 17) of patients, especially in the 19–39 age-group. The olfactory threshold was only significantly correlated with the semantic memory scores. Conclusions: Similar to all cognitive disorders, semantic disorders can have a negative impact on quality of life if left untreated. It is essential to carry out specific assessments of post COVID-19 patients to accurately determine their disorders and to put in place the best possible rehabilitation, such as speech and language therapy, to avoid quality-of-life impairment.

What about using sniffin' sticks 12 items test to screen post-COVID-19 olfactory disorders?

Background

Post-COVID-19 Olfactory impairment has a negative impact on quality of life. The Sniffin Sticks test 12 items (SST-12) can be used in quick olfactory disorders screening. Its evaluation in a post-covid-19 situation was the main objective of this work.

Methods

All patient impaired with a post-COVID olfactory loss were included while consulting to the ENT department. The clinical examination included an olfaction recovery self-assessment (VAS), a nasofibroscopy, a quality of life (QoL) assessment, the complete Sniffin’ Sticks Test (SST), and the SST-12.

Results

Among the 54 patients included, 92% (n = 50) were correctly screened as olfactory impaired by SST-12. We report excellent correlations between SST-12 and SST (rho ₍₅₂₎ = 0.98, p < 0.001), QoL(rho₍₅₂₎ = 0.33 p = 0.016), or VAS (rho₍₅₂₎ = 0.49, p < 0.001) assessments.

Conclusions

SST-12 is a quick and reliable tool to screen large-scale population of post-COVID-19 olfactory impaired patients and could be used in a general daily clinical practice.