The purpose of this multicenter case-control study was to evaluate a group of patients at least 1 year after coronavirus disease 2019 (COVID-19) with Sniffin’ Sticks tests and to compare the results with a control population to quantify the potential bias introduced by the underlying prevalence of olfactory dysfunction (OD) in the general population. The study included 170 cases and 170 controls. In the COVID-19 group, 26.5% of cases had OD (anosmia in 4.7%, hyposmia in 21.8%) versus 3.5% in the control group (6 cases of hyposmia). The TDI score (threshold, discrimination, and identification) in the COVID-19 group was significantly lower than in the control group (32.5 [interquartile range, 29-36.5] vs 36.75 [34-39.5], P < .001). The prevalence of OD was significantly higher in the COVID-19 group, confirming that this result is not due to the underlying prevalence of OD in the general population.

Introduction Olfactory dysfunction (OD) is a well know symptom of coronavirus disease 2019 (COVID-19), accounting for 48 to 85% of patients. In 1 to 10% of cases, patients develop a chronic olfactory dysfunction (COD), lasting more than 6 months. Recently, platelet-rich plasma (PRP) was used in patients with non-COVID-19 COD and authors reported encouraging results. Methods In the present study, we investigated the usefulness and safety of PRP injection in 56 patients with COVID-19 COD by the Sniffing Stick test (TDI score) and a linker-scale from 0 (none) to 3 (strong) and we compare the result to a control group. Results At 1 month post-PRP injection, the mean TDI scores significantly improved by 6.7 points in the PRP group ( p < 0,001), the mean self-assessment of improvement in smell function was 1.8 (mild-to-moderate) in the PRP group, which was significantly higher than the score (0.3) in the control group ( p < 0,001). Conclusion Our results showed that PRP in the olfactory cleft can increase the olfactory threshold 1 month after the injection. Moreover, our results suggest that timing of treatment may be an important factor and that PRP is a safe treatment, because no adverse effects were reported throughout the study. Trial registration number: NCT05226546.

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Introduction and aim Olfactory dysfunction (OD) is a prevalent symptom of coronavirus disease 2019 (COVID-19), accounting for 48 to 85% of patients. In 1 to 10% of cases, patients develop a chronic olfactory dysfunction (COD) lasting more than 6 months. Recently, platelet-rich plasma (PRP) was used in patients with non-COVID-19 COD and authors reported encouraging results. In the present study, we investigated the usefulness and safety of PRP injection in 56 patients with COVID-19 COD. Material and methods 56 adult patients with COVID-19 COD were prospectively recruited from CHU Saint-Pierre. Participants underwent olfactory function testing by means of the Sniffin Sticks Test battery (Medisense, Groningen, Netherlands), resulting in the Threshold Discrimination Identification TDI score, at baseline and 1 month post-injection. PRP injections were performed in each olfactory cleft via nasal endoscopy and under local anesthesia by the same physician (YS), following the protocol of Yan et al. (GS30-PURE II Protocol A: Emcyte, Ft Myers, Florida).1 Olfactory outcome from patients who had PRP injection were compared to a control group made of patient with COVID-19 COD treated with nasal irrigation during a month. Results 36 patients received a PRP injection. Among those, 6 were lost to follow-up and therefore excluded. The control group, matched for age, gender and TDI score at baseline, included 26 patients. Both groups were comparable regarding demographics, duration of OD, and TDI scores. At 1-month post-PRP injection, the mean TDI score significantly improved by 6.7 points in the PRP group (p<.001), while there was no significant change in controls. There was a moderate negative correlation between TDI score difference and duration of OD in the PRP group (r=.387, p=.035) but not in controls. No adverse effects were reported throughout the study Conclusions Our results showed that PRP in the olfactory cleft can increase the olfactory threshold one month after the injection. Moreover, our results suggest that timing of treatment may be an important factor.

An innovative and noninvasive technique for closure of persistent tracheoesophageal fistula after total laryngectomy is described. In our preliminary study, two patients were included. No clinical and radiological signs of locoregional recurrence prior to treatment were diagnosed. We performed local injections of autologous platelet-rich plasma (PRP) according to our protocol. Complete closure of the fistula was observed in both patients who were able to take normal feeding. No side effects associated with the procedure were observed. These preliminary results are encouraging to consider PRP injection before more invasive surgical techniques in the treatment of persistent tracheoesophageal fistulas after total laryngectomy.