Effectiveness of Platelet-Rich Plasma in Long-Lasting Post-Viral Olfactory Dysfunction: A Case-Series

Introduction: To date, there are few solutions for patients with long-lasting postviral olfactory dysfunction (OD). Recent studies suggested that the injection of platelet-rich plasma (PRP) into the olfactory clefts may accelerate the recovery of smell sense in COVID-19 patients with short-lasting OD. The objective of this study was to investigate PRP effectiveness in patients with a long-lasting non-SARS-CoV-2 OD.

Methods: In this preliminary prospective study, PRP injections in the olfactory clefts were performed in 42 consecutive patients with a long-lasting postviral OD (mean duration: 8.7 years). Olfactory function was evaluated with Olfactory Disorder Questionnaire (ODQ) and threshold, discrimination, and identification (TDI) tests at baseline and 6-month post-injection.

Results: The pre to 6-month post-injection TDI tests significantly improved from 10.3±10.2 to 20.12±12.07 (p=0.001), while the mean olfactory disorder questionnaire (ODQ) significantly decreased from 29.8±13.0 to 23.4±11.3 (p=0.013). The minimal clinically important difference of the TDI and the ODQ were 9.8 and 6.4, respectively. Age was inversely associated with the 6-month threshold score.

Conclusions: PRP appears to be a promising therapeutic strategy for long-lasting postviral OD. Our findings support the conduction of controlled randomized trial in this population of patients.