A blinded crossover study of the effect of local anesthetic on subjective nasal obstruction
Summary:
ModTridD is a study with 16 healthy participants which underwent testing to measure their objective and subjective nasal obstruction, after local anesthetic spray and placebo (normal saline solution)
Why did we undertake this study?
We undertook this study to investigate whether we could recreate the sensation of a blocked nose in healthy subjects by using local anesthetic spray in their nose. The reason for the study is that about 25% of the population has a chronic blocked nose, often with a clear reason (for example a cold, a deviated septum or because of allergies). In about 30% of patients, there is no clear explanation. In these patients, we suspect that the intranasal trigeminal system, responsible for registering air flow through the nose, is not working properly. At the moment, there is no standardized way to diagnose these patients, and the reason for the problem with the trigeminal system can be a lot different between patients, making it difficult to create studies with enough research subjects.
What is the specific question(s) we wanted to answer?
The specific question we wanted to answer is whether we could create a pathological situation in a healthy subject, in order to create a model which could be used in the future to help performing further studies on the topic of intranasal trigeminal dysfunction and the related chronic nasal obstruction.
What did we find?
We found that the trigeminal lateralization task, which allows us to test the sensitivity of the intranasal trigeminal system, was normal in our healthy subjects when tested before treatment, and was abnormal/pathologic after using the local anesthetic. We also had the subjects fill in questionnaires which are used by patients with chronic nasal obstruction, and we saw that their scores were normal before local anesthetic, and elevated after local anesthetic. To make sure that the local anesthetic did not have an influence on the patency of the nose we performed a breathing test through the nose before and after local anesthetic, which was the same in both situations, meaning that the effect on nasal breathing is purely due to the trigeminal system, and not a physical obstruction.
What are the implications of our findings?
Our study shows that topical intranasal anesthesia reduces intranasal trigeminal function, resulting in subjectively reduced nasal patency, meaning patient have complaints compatible with a blocked nose after we use the local anesthetic, and that the intranasal trigeminal system is responsible for this feeling. Our results can now be used in future studies to create a group of very similar individuals, which will make it easier to create big enough groups to investigate other aspects of the intranasal trigeminal system.
Authors:
- Chloé Migneault-Bouchard (Université du Quebec)
- Frans Boselie (CHL)
- Johannes Frasnelli (Université de Montréal)
More information:
https://pubmed.ncbi.nlm.nih.gov/39893621/
or
https://www.rhinologyjournal.com/Abstract.php?id=3224