Smell Dysfunction

Isotretinoin is a common medicine used to treat moderate to severe acne. It often causes dryness of the skin and the inside of the nose. Because a normal sense of smell depends on a healthy nasal lining, this dryness may affect how well a person can smell. This study will examine whether isotretinoin treatment changes the sense of smell in adults with acne. Before starting isotretinoin, participants will complete a standardized smell test and two short questionnaires about nasal symptoms and quality of life: the Nasal Obstruction Symptom Evaluation (NOSE) scale and the 22-item Sino-Nasal Outcome Test (SNOT-22). After at least 4 weeks of treatment, the same smell test and questionnaires will be repeated. By comparing results before and after treatment, the study will test the hypothesis that isotretinoin has a negative effect on olfactory function and may reduce patients' ability to smell.

This research study aims to investigate the function of the olfactory lining in the nasal cavity and its potential alterations in both healthy and diseased conditions. The olfactory lining is involved in the sense of smell. The purpose of this study is to collect tissue from the nasal cavity.

Persistent smell loss that can include diminished or distorted smell function is a common symptom of long COVID syndrome. There are limited treatment options for long COVID-related smell loss. This study aims to determine the efficacy of two at-home treatments, smell training and non-invasive trigeminal nerve stimulation. This study requires participants to conduct daily at-home treatment sessions, attend three in-person study visits at the MUSC Department of Psychiatry and Behavioral Sciences, and complete electronic questionnaires over the 12-week trial, and again at the six-month timepoint. Participants in this trial may benefit directly with an improvement in sense of smell. However, participation may also help society more generally, as this study will provide new information about long COVID-related smell loss and its treatment.

This study aims to evaluate the effectiveness of hormone nasal drops in the olfactory cleft combined with olfactory training for treating postinfectious olfactory dysfunction (PIOD). The main questions this clinical trial seeks to answer are: Can the combination of hormone nasal drops and olfactory training improve smell function better than olfactory training alone in PIOD patients? How does this combined treatment work?

This study aims to compare the efficacy of steroid nasal drops targeting the olfactory cleft versus traditional intranasal steroid sprays in improving olfactory function in patients with chronic rhinosinusitis (CRS) with olfactory cleft obstruction. The main questions this clinical trial aims to answer are: 1. Efficacy Comparison: Is olfactory improvement greater with olfactory cleft-targeted steroid nasal drops compared to standard nasal steroid sprays in CRS patients? 2. Mechanism Exploration: How do changes in inflammatory markers, obstruction severity, and olfactory test results explain the potential benefits of this treatment approach?

Smell/taste disorders are common conditions with a significant impact on quality of life. In September 2021, a specific consultation for patients with smell and taste disorders was initiated at the ENT-HNS (ear, nose, and throat, head and neck surgery) department of UZ Leuven, partly in light of post-COVID-19 related smell disorders. With this observational ambidirectional study, the investigators aim to better map smell/taste disorders in the Belgian/Flemish population. Using standard-of-care diagnostic tests and structured questionnaires, the investigators strive to gain more insight into the severity, impact, and progression/prognosis of smell/taste disorders.

* Causes of olfactory dysfunction can be classified into conductive and sensorineural causes. * Conductive causes are mainly due to structural nasal problem, which can be treated by nasal surgery * Sensorineural causes included post-infection, post-head injury, post Head and Neck irradiation and other central nervous system diseases. * Olfactory Training is well established treatment for sensorineural olfactory dysfunction in foreign countries. * Olfactory Training by neurological chemosensory stimulation using aromatic substances delivered via electronic portable aromatic rehabilitation (EPAR) diffuser was proved to be effective treatment in COVID-19 related olfactory dysfunction in recent Hong Kong study. * However, there is a lack of local study on the effect of Olfactory Training in other non-COVID-19 sensorineural causes of olfactory dysfunction in Hong Kong population.