The Efficacy of Modified Olfactory Training Method for Patients With Post-viral Olfactory Dysfunction

Not Applicable

Recruiting

• Conditions: Olfactory Dysfunction; Post Viral Olfactory Dysfunction (PVOD)

• Registration Number: NCT06829706
• Lead Sponsor: Peking University Third Hospital

Brief Summary

The goal of this clinical trial is to validate the effectiveness of the modified olfactory training device, the main questions it aims to answer are: Is the modified olfactory training device effective in treating patients with post-viral olfactory dysfunction? Compared to the conventional device, how efficient is the modified olfactory training device for improving olfactory function?

Detailed Description

Background The aim of this article is to present the research protocol for a randomized, controlled, multi-center, placebo study that will assess the olfactory function and the effect of an intervention based on olfactory training in patients with post-viral olfactory dysfunction, and compare it with traditional olfactory training. The sample selection will follow the multi-center principle. The olfactory training (OT) intervention will last for 12 weeks.

Evaluation The primary endpoint will be the change in olfactory ability from baseline to the 12-week intervention or control period. The intervention effect will be evaluated by the total score of the Sniffer Stick Test (SST)-Threshold, Discrimination and Identification (TDI)-Extended Version. Secondary endpoints will be changes in olfactory bulb volume and shape, olfactory-related brain area volume, olfactory and trigeminal nerve-related potentials, and cognitive questionnaires.

Conclusion（objective） The present study aimed to explore the efficacy of the modified olfactory training device (MOT), and compare COT and MOT with respect to the resultant improvement in olfactory function.

At the same time, our study will use a variety of outcome indicators to evaluate the changes in patients before and after treatment, which will lay the foundation for exploring the mechanism of olfactory training in treating patients with post-viral olfactory disorders.

Study Timeline

• Status Verified: 2025-02
• Study First Submitted: 2025-02-06
• Study First Submitted QC: 2025-02-13
• Last Update Submitted: 2025-02-13
• Study First Posted: 2025-02-17
• Last Update Posted: 2025-02-17
• Study Start: 2025-03-22
• Primary Completion: 2027-03-22
• Study Completion: 2027-05-22

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 150

Inclusion Criteria

1. Age 18-80 years old, gender not limited.
2. Patients diagnosed with olfactory dysfunction following infections of the upper respiratory tract, as determined by Sniffin' Sticks test (including TDI value test).
3. Voluntarily signs the informed consent form.

Exclusion Criteria

1. Patients with post-traumatic olfactory dysfunction, rhinosinusitis-related dysfunction and olfactory dysfunction caused by other reasons.
2. Patients with concomitant sinonasal disease.
3. Patients with chronic diseases, such as hypertension, diabetes, bronchopneumonia, chronic obstructive pulmonary disease, etc.
4. Patients with serious coexisting diseases: such as malignant tumors, etc., with a life expectancy of less than 2 years.
5. Patients who cannot tolerate olfactory function testing and treatment.
6. Patients who have taken oral glucocorticoids, antibacterial drugs, anti-leukotrienes, antihistamines, or received olfactory training within four weeks will be excluded.
7. Patients who are receiving treatment that affects olfactory recovery.
8. Patients with smoking habits.
9. Patients who are already or plan to be pregnant.
10. According to the judgment of the researchers, the patient cannot complete this study or cannot comply with the requirements of this study (such as memory or behavior abnormalities, depression, heavy drinking, previous breach of contract).
11. Patients who did not consent for participating in the study.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
The total scores in the "Sniffin 'Sticks" test	Baseline,Month 3,Month 6,Month 12,Month 24	This olfactory test consists of three subtests that respectively measure odor threshold (T), odor discrimination (D), and odor identification (I). Each subtest has a maximum score of 16, and the sum of the scores from the three subtests provides the global olfactory score (TDI score; Threshold, Discrimination, Identification) with a maximum of 48 points. Patients with a TDI composite score≥30.5 are defined as normosmic. In contrast, those with a TDI composite score between 16.5 and 30.5 are defined as hyposmic, and patients with a TDI composite score\<16.5 are defined as functionally anosmic. Based on previous literature, we have established a 5.5 points improvement in the TDI composite score as a significant change.

Secondary Outcome Measures

Name	Time	Method
OB volume and shape measurement	Baseline,Month 3,Month 6,Month 12,Month 24	OB volumetric evaluations will be performed with a 3-Tesla MRI system with coronal T2-weighted fast spin-echo images that included the anterior and the middle parts of the skull base.; The OB volume will be measured using manual segmentation. The contours of the left and the right OBs will be manually delineated. The proximal limit of the OB will be determined on the basis of the sudden change in the diameter at the beginning of the olfactory tract. After all surfaces are added and multiplied by the slice thickness, the volume in cubic millimeters will be obtained for the right and the left OBs, and the total OB volume will be calculated as the sum of the two values.; Measurements will be performed blindly twice by two examiners. When the difference in volume is \> 10%, the examiners will perform a third measurement together.; We have interpreted oval, round, triangular, and bean/boat/banana shapes as normal variants of OB shape.Atrophy will be interpreted as flattened OB.
MRI volumetric evaluation related to GM	Baseline,Month 3,Month 6,Month 12,Month 24	Magnetic resonance imaging (MRI) scans will be performed on a 3T Siemens Verio scanner with a 12-channel phased-array head coil,measuring gray matter(GM) volumes to explore the connection between olfactory function and brain regions.
MRI volumetric evaluation related to WM	Baseline,Month 3,Month 6,Month 12,Month 24	Magnetic resonance imaging (MRI) scans will be performed on a 3T Siemens Verio scanner with a 12-channel phased-array head coil,measuring white matter(WM) volumes to explore the connection between olfactory function and brain regions.
MRI volumetric evaluation related to CSF	Baseline,Month 3,Month 6,Month 12,Month 24	Magnetic resonance imaging (MRI) scans will be performed on a 3T Siemens Verio scanner with a 12-channel phased-array head coil,measuring cerebrospinal fluid(CSF) volumes to explore the connection between olfactory function and brain regions.
Event-related potentials (ERPs)	Baseline,Month 3,Month 6,Month 12,Month 24	Event-related potentials include olfactory event-related potentials(oERPs) and trigeminal event-related potentials (tERPs).; We will use an OM6b olfactometer to generate ERPs after we have stimulated patients with phenethyl alcohol per standard methods.We infuse olfactory- and then trigeminal-nerve stimuli into the nasal cavity at a constant temperature and flow rate.We will place reference electrodes in the left and right earlobes When analyzing the records offline, we will exclude those contaminated by blinking or other interference . After amplification and filtering, we will obtain stable oERPs and tERPs waveforms.
Questionnaire of Olfactory Disorders	Baseline,Month 3,Month 6,Month 12,Month 24	Questionnaire of Olfactory Disorders (QOD) determines the impact of olfactory dysfunction on daily life (70). The QOD consists of 52 statements, which can be divided into 3 domains: 39 negative statements (degree of suffering; NS), 5 positive statements (positive effects and coping strategies) and 8 socially desired statements ("lie scale") .
Visual analogue scale for olfactory training	Baseline,Month 3,Month 6,Month 12,Month 24	Subjective ratings of olfactory function will be also recorded at baseline and follow-up appointments by means of a visual analogue scale, scoring from 0 to 100. On this scale, 0 represents complete olfactory loss and 100 perfect olfactory function. In addition, patients were asked about the presence of qualitative olfactory disorders such as parosmia.

Trial Locations

Locations (1)

Bejing; 🇨🇳 Beijing, China