Treatment strategies for postviral olfactory dysfunction: A systematic review

Abstract

Background: The coronavirus disease 2019 (COVID-19) pandemic has been associated with a dramatic increase in postviral olfactory dysfunction (PVOD) among patients who are infected. A contemporary evidence-based review of current treatment options for PVOD is both timely and relevant to improve patient care. Objective: This review seeks to impact patient care by qualitatively reviewing available evidence in support of medical and procedural treatment options for PVOD. Systematic evaluation of data quality and of the level of evidence was completed to generate current treatment recommendations. Methods: A systematic review was conducted to identify primary studies that evaluated treatment outcomes for PVOD. A number of medical literature data bases were queried from January 1998 to May 2020, with completion of subsequent reference searches of retrieved articles to identify all relevant studies. Validated tools for the assessment of bias among both interventional and observational studies were used to complete quality assessment. The summary level of evidence and associated outcomes were used to generate treatment recommendations. Results: Twenty-two publications were identified for qualitative review. Outcomes of alpha-lipoic acid, intranasal and systemic corticosteroids, minocycline, zinc sulfate, vitamin A, sodium citrate, caroverine, intranasal insulin, theophylline, and Gingko biloba are reported. In addition, outcomes of traditional Chinese acupuncture and olfactory training are reviewed. Conclusion: Several medical and procedural treatments may expedite the return of olfactory function after PVOD. Current evidence supports olfactory training as a first-line intervention. Additional study is required to define specific treatment recommendations and expected outcomes for PVOD in the setting of COVID-19.

Platelet-rich plasma injection in the olfactory clefts of COVID-19 patients with long-term olfactory dysfunction

“…A proportion of patients ( n = 37) were re-evaluated 2 months after the PRP injection, reporting significant improvements of ODQ and TDI scores. These data supported those of the preliminary study of Yan et al, who reported a substantial improvement of TDI scores in five out of seven patients [ 11 ]. The usefulness of PRP injection into the olfactory cleft was recently supported by Steffens et al [ 22 ] who observed that patients treated by PRP injection for a persistent (> 1 year) OD reported higher increase of TDI score improvements 1 month after the PRP injection compared with patients who did not benefit from injection.…”

“…The mean time of PRP extraction and injection found in the present study corroborated those of studies in which PRP procedure was performed for other otolaryngological indications [ 19 , 21 ]. The mean injected PRP amount was 1.2 mL/side, which was consistent with the data of Yan et al [ 11 ].…”

“…The occurrence of transient epistaxis was related to the realization of several mucosa injection points and was the main adverse event. Both injection pain and risk of transient epistaxis were, however, not reported in the study of Yan et al, which limits the comparison of our data with the current literature [ 11 ]. The mean time of the procedure was 18.4 min, which makes the PRP olfactory cleft injection a rapid procedure.…”

“…In 2019, Yan et al . [ 11 ] published a preliminary paper describing the injection of platelet-rich plasma (PRP) into the olfactory cleft of seven individuals with post-viral OD as a new potential approach to improve the smell recovery. To date, there is no study assessing feasibility, safety, and tolerance of this procedure in large cohort of patients.…”

Efficacy and safety of acupuncture in the treatment of the sequela of olfactory disorders after infection with COVID-19: A protocol for systematic review and meta analysis

“…[ 18 ] At present, olfactory training is recommended as a first-line therapy for the treatment of PVOD, with topical corticosteroids, sodium citrate, oral vitamin A, and TCA considered as optional therapies for appropriately selected patients. [ 19 ] However, these treatments are sometimes ineffective. No high-level evidence are available to date on the efficacy of these measures in PVOD and further study is needed.…”