Comparative Efficacy of Intranasal Corticosteroids, Structured Olfactory Training, and Olfactory Cleft Platelet-Rich Plasma Injection in Isolated Post-Viral Olfactory Dysfunction

Abstract

Background: Post-viral olfactory dysfunction (PVOD) is a common disorder which often persists for long durations with limited effective treatment options. Currently, intranasal corticosteroids (INCs) and olfactory training (OT) demonstrate modest therapeutic efficacy, while regenerative approaches such as platelet-rich plasma (PRP) have recently emerged as promising interventions. Objective: To compare the efficacy of INCs, structured OT, and olfactory cleft PRP injection in improving olfactory function in patients with isolated PVOD. Methods: This prospective randomized controlled trial included 135 patients with persistent PVOD. Those were randomly allocated into three groups; Group1: INCs alone (n=45), INCs combined with OT (n=45), and combined therapy including INCs, OT, and PRP injection (n=45). Olfactory function was assessed using the Sniffin’ Sticks Threshold–Discrimination–Identification (TDI) score, while subjective improvement was evaluated using a visual analog scale (VAS). Assessments were conducted at baseline, 1 month, 3 months, and 6 months. Results: All groups showed significant improvement in olfactory function over time. However, the level of improvement varied significantly between groups (p < 0.001). The mean TDI score increased by 5.7 ± 2.8 in the INCs group, 11.3 ± 3.4 in the INCs plus OT group, and 16.7 ± 3.9 in the PRP combination group. Clinically significant improvement (≥6-point increase in TDI) was achieved in 40.0%, 64.4%, and 80.0% of patients, respectively (p < 0.001). Normosmia was restored in 20.0%, 37.8%, and 53.3% of patients, respectively. Subjective VAS scores also improved significantly, showing better improvement observed in the PRP group (p < 0.001).  Conclusion: Combined therapy including INCs, OT, and PRP injection provides better improvements in both objective and subjective olfactory outcomes compared with conventional therapies alone. These findings support a multimodal therapeutic approach targeting both inflammation and neuroregeneration in the management of PVOD.