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.
‣ To be eligible to participate in this study, an individual must meet all the following criteria:
• Adult subjects, any sex, aged 18 or older.
• Ability to understand and willingness to sign a written informed consent document.
• Willingness and ability to comply with and participate in all study procedures and availability for the duration of the study.
• Due to the extensive questionnaires (administered in English language only) that participants must complete independently, fluency in the English language is needed. Hence, participants must be able to read and understand English.
• \* To maintain consistency in the study, we will prioritize enrolling individuals who have experienced olfactory loss for no more than one year. However, the duration of olfactory dysfunction can vary significantly, often due to delayed awareness or recognition of the condition. For instance, anosmia and hyposmia are frequently reported as long-term consequences of infections, meaning some participants may have experienced prolonged dysfunction. Given this variability, we will treat the duration of olfactory loss as a potential confounding factor in our data analysis, ensuring that its influence is appropriately accounted for when interpreting the results. Other than healthy controls, participants reporting smell loss must also meet one or more of the following criteria to be eligible for the study:
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• General Smell Loss:
• Individuals who have experienced any degree of smell loss or olfactory dysfunction, regardless of the cause. This includes both partial, complete to distorted loss of the sense of smell (hyposmia, anosmia or parosmia).
• Post-COVID-19 or Virus-Related Smell Loss:
• Individuals experiencing olfactory dysfunction due to COVID-19, influenza or other respiratory viruses, leading to both acute and long-term (chronic) smell loss
• Sinonasal Smell Loss:
• Participants diagnosed with smell loss related to sinonasal conditions, such as:
⁃ Chronic Rhinosinusitis: Long-term inflammation of the sinuses that impairs olfactory function.
⁃ Nasal Polyps: Growths in the nasal passage that obstruct airflow and affect the sense of smell.
• Exposure to Toxic Chemicals:
‣ Patients who have encountered olfactory dysfunction due to exposure to harmful chemicals or environmental toxins that can impair the olfactory receptors or neural pathways responsible for the sense of smell.
‣ 5\. Chemotherapy-Induced Smell Loss:
‣ Individuals who have experienced smell loss as a side effect of undergoing chemotherapy. This includes patients who are in active treatment as well as those who have completed chemotherapy but continue to suffer from olfactory impairment.