Effects of Olfactory Training in Patients With Postinfectious Olfactory Dysfunction.

Objectives: Postinfectious olfactory dysfunction (PIOD) is the most common etiology of olfactory dysfunction, and olfactory training (OT) is an accepted treatment modality for PIOD. Some studies have investigated OT in Korean patients, but they involved odorants unfamiliar to Koreans or had no control group. The aim of this study was to verify the efficacy of OT in PIOD patients, using odorants familiar to Koreans and including a control group.

Methods: We enrolled a total of 104 Korean patients with PIOD over the 3-year study period. All participants were assessed using endoscopy and an olfactory function test at the baseline assessment and 3 months after OT. The olfactory function test was performed using the Korean version of Sniffin' stick (KVSS) II. Nasal and psychological function was evaluated using a visual analog scale and the Mini-Mental State Examination. OT was performed over a period of 3 months, using five odorants (rose, lemon, cinnamon, orange, and peach).

Results: OT improved olfactory function in approximately 40% of subjects over a period of 12 weeks compared to non-OT subjects. A comparison of changes between the initial and follow-up assessments demonstrated that the OT group had significantly better olfactory results for the total KVSS II, threshold, and identification scores than the non-OT group. The degree of olfactory improvement after OT was affected by the initial score.

Conclusion: The effects of OT in patients with PIOD were demonstrated in this study. A meaningful contribution of this study is that Korean patients were tested using odors familiar to them in comparison with a control group.