Postinfectious Olfactory Dysfunction: Oral Steroids and Olfactory Training versus Olfactory Training Alone: Is There any Benefit from Steroids?

Abstract

Introduction: There are limited treatment options for postinfectious olfactory dysfunction (PIOD). Olfactory training has recently been used in clinical practice, but no medical treatment is widely accepted. Although there is weak evidence for their value, some physicians use oral corticosteroids as first-line treatment. The aim of this study was to compare combined oral methylprednisolone and olfactory training with olfactory training alone in the management of PIOD.

Methods: This prospective cohort study included 131 patients with PIOD over a 2-year period before the COVID-19 pandemic. Seventy-eight patients who were treated with oral methylprednisolone and olfactory training (group A) were compared with 53 patients who were treated with olfactory training only (group B). Olfactory function was evaluated with "Sniffin' Sticks" at baseline and 2, 8, and 16 weeks after initial assessment. Patients who improved after steroid treatment underwent magnetic resonance imaging of the paranasal sinuses, skin prick tests, lung spirometry, and sputum eosinophil assessment.

Results: Oral steroids improved 19.23% of patients (n = 15) of group A. History, clinical evaluation, imaging, and laboratory tests identified an inflammatory background in half of them (n = 8). The remaining 7 had no findings of nasal inflammation, and all had a short history of olfactory dysfunction. Both groups significantly improved in olfactory testing results at the end of the olfactory training scheme without significant difference between them.

Conclusions: The percentage of improved patients after oral methylprednisolone was relatively low to suggest it as first-line treatment. Half of the improved patients had an underlying upper airway inflammatory condition not related to the infection that caused the acute loss of olfactory function.

Keywords: Anosmia; Olfactory training; Postinfectious olfactory dysfunction; Smell; Steroids.