Longitudinal Deep Phenotyping of Central Mechanisms in Dysosmia: A Pilot Study Using Electrobulbogram (EBG), Functional MRI (fMRI), and Diffusion-Weighted Imaging (DWI)

Background: Loss of the sense of smell can seriously affect a person's quality of life. The ability to smell can be damaged by many factors, including illnesses, injuries, and exposure to toxic chemicals. The effects can vary, including complete loss of smell, partial loss, and parosomia, which is when things smell differently than they should. Objective: To study how brain function changes in people with different types of smell disorders. Also, to look at how smell loss affects quality of life over time. Eligibility: People aged 18 years or older with a disorder that affects their sense of smell. Healthy volunteers are also needed. Design: Participants will have 5 study visits over 1 year. They will have various tests and procedures: Smell tests. They will have several tests that involve smelling different items and answering questions. Questionnaires. They will answer questions about their health, mood, sense of smell, and daily habits. Magnetic resonance imaging (MRI) scans. They will lie on a bed that slides into a tube. Padding will hold their head still. They will smell different odors while in the scanner. Electrobulbogram (EBG). They will wear a soft cap with sensors that measure brain activity. They will smell different odors while wearing the cap. Nasal endoscopy. A flexible tube will be inserted into a nostril to view the inside of the nose. Biopsy. A numbing substance will be sprayed into the nose. Then a scissor-like tool will be used to collect a sample of tissue from one or both nasal passages. Samples of blood, urine, and nasal fluid will be taken.

NCT Number	NCT07149428
Lead Sponsor	National Institute on Deafness and Other Communication Disorders (NIDCD)
Conditions	Respiratory Tract Infection, Smell Disorder, Influenza, Rhinosinusitis, COVID-19, Depression, Parosmia, Hyposomia +2 more
Enrollment	80 participants
Start Date	2026-08-19
Primary Completion	2029-09-30 (estimated)
Study Completion	2029-10-14 (estimated)
Updated on ClinicalTrials.gov	2026-08-14