Therapeutic use of steroids in non-chronic rhinosinusitis olfactory dysfunction: a systematic evidence-based review with recommendations.

BACKGROUND: Olfactory loss is a common and debilitating disease with limited treatment options, particularly for olfactory dysfunction not related to sinonasal inflammation. Both topical and systemic steroids have been used as treatments for olfactory loss. This study systematically reviews the literature on the efficacy of steroids for non-chronic rhinosinusitis (CRS)-related olfactory loss and provides recommendations.
METHODS: A literature search of PubMed, Ovid, EMBASE, and the Cochrane Database was performed according to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Inclusion criteria included original data, English-language articles on steroid treatment (topical and systemic) for olfactory loss unrelated to sinonasal inflammation. Data was collected on study design, olfaction dysfunction etiology, clinical outcomes, and level of evidence. Two investigators reviewed all articles independently, with a third acting as a mediator for any disagreements in recommendation.
RESULTS: Of 866 abstracts identified, only 15 studies met inclusion criteria and were systematically reviewed. Level 4 evidence suggests oral steroids can improve olfactory loss. Level 1B evidence demonstrates topical steroid rinses improve olfactory dysfunction in a select group of patients. Topical steroid sprays show no improvement across several levels of evidence.
CONCLUSION: There is a paucity of high-quality studies demonstrating efficacy of either topical or oral steroids for olfactory dysfunction unrelated to sinonasal disease. The only level 1 evidence suggests using steroid rinses to improve olfactory outcomes in select patients, with weaker evidence supporting use of oral steroids. Topical steroid sprays do not improve olfactory dysfunction in this patient population and are not recommended.