Efficacy of olfactory-visual combined training on post-viral olfactory dysfunction: a randomized controlled trial

Area of Science:

• Neurology
• Otolaryngology
• Sensory Science

Background:

• Post-viral olfactory dysfunction (PVOD) is a common cause of smell loss.
• Olfactory training (OT) is a standard treatment for olfactory dysfunction, involving repeated odor exposure to regenerate olfactory pathways.
• Identifying the most effective OT methods is crucial for improving patient outcomes.

Purpose of the Study:

• To compare the effectiveness of different olfactory training (OT) methods in patients with post-viral olfactory dysfunction (PVOD).
• To investigate the impact of olfactory-visual combined stimulation on olfactory function recovery.
• To explore factors influencing OT efficacy, such as education level and gender.

Main Methods:

• 120 PVOD patients were randomized into four groups: OT-4 (4 odors), OT-8 (8 odors), OT-4+VS (4 odors with visual stimuli), and OT-0 (odorless control).
• Training involved twice-daily 5-minute sessions for six months.
• Olfactory function was assessed using the Chinese Smell Identification Test (CSIT), olfactory Visual Analog Scale (VAS), olfactory cleft endoscopy score (OCES), Questionnaire of Olfactory Disorders (QOD), and Patient Health Questionnaire-9 (PHQ-9).

Main Results:

• All three OT groups (OT-4, OT-8, OT-4+VS) showed significant improvements in CSIT compared to the control group (p < 0.05).
• The OT-4+VS group demonstrated the fastest and most effective olfactory improvement.
• While OT-4 and OT-8 showed no significant CSIT difference, OT-8 improved in the latter half of the study. OT-4 and OT-4+VS significantly improved VAS scores (p < 0.05).
• No significant improvements were observed in OCES, QOD, or PHQ-9 scores across any group.
• Higher education levels correlated with greater olfactory function improvement (p < 0.01), and female patients reported better CSIT and VAS scores (p < 0.01, p < 0.001).

Conclusions:

• Combined olfactory-visual stimulation offers a rapid and effective approach for improving olfactory function in PVOD patients compared to traditional OT.
• Education level and gender may play a role in the success of olfactory training interventions.
• Further research may explore optimizing olfactory-visual training protocols for enhanced recovery.