A proof-of-concept study for vitamin A nasal drops in post-viral olfactory loss
Post-viral (infectious) olfactory loss/dysfunction (PVOL/PIOD)
The researchers will invite people who have been found to have smell loss due to a previous viral infection to join the study. They can join when they attend the Norfolk Smell & Taste Clinic, or through Fifth Sense, the smell and taste disorders charity. Those able to join will be randomly allocated to one of two groups: 38 patients will receive a 12-week course of nasal vitamin A drops (Vitadral Topfen Oral Drops [Aristo Pharma, Berlin, Germany]) and 19 will receive standard care which is currently no treatment. Both sets of patients will receive brain scans, before and after the 12-week interval. The researchers will look for changes in the size of the olfactory bulb. They will also look at activity in areas of the brain linked to recognising smells. The patients will be smelling odours (roses and rotten eggs) while brain scans are taken that use a magnetic coil to create images. A smell test and a questionnaire will also measure smell loss and its daily impact at the two visits.
1. A partial or total loss of smell due to post-viral olfactory loss as confirmed on history, examination and with a smell test (TDI) score of <31/48 2. Within 3 years of the precipitating viral infection
1. Participants with a history of: 1.1. Chronic rhinosinusitis with/without nasal polyposis 1.2. Severe nasal septal deviation 1.3. Major prior head injury 1.4. Congenital olfactory loss 1.5. Use of concurrent intranasal medications or possible medications know to affect olfaction 1.6. Chronic renal disease 1.7. Chronic hepatic disease 1.8. Allergy to peanuts, soy or vitamin A (drops contain peanut oil) 2. Significant medical, surgical or psychiatric disease that in the opinion of the PI would affect subject safety or influence the study outcomes 3. Current taking oral vitamin A supplements 4. Age less than 18 years 5. Pregnant women 6. Depending on the situation with regards to nasal endoscopy and COVID-19 at the time of study commencement we will exclude the following based on the endoscopy or the initial MRI scan: 6.1. Participants with any endoscopic findings of: 6.1.1. Chronic rhinosinusitis with/without nasal polyposis 6.1.2. Severe nasal septal deviation (preventing passage of 4mm endoscope) 6.1.3. Other inflammatory sinonasal disease 6.2. Participants with MRI changes indicating oedema in the sinuses and/or olfactory clefts 7. Participants must not have any metal implants, such as a pacemaker etc, as is standard for MRI scanning. 8. Any participants who move excessively during scanning 9. Any participant with a combined OBV of >85 mm³ as it is unlikely they will demonstrate a significant increase in overall volume based on previous studies of OBV