ABSTRACT
Smell dysfunction is one of the most frequent symptoms in COVID-19 patients. In the early stages of the disease it allows to identify positive subjects. The odorous substances recognize two different systems in the olfactory epithelium: the olfactory and the trigeminal systems that coexist and interact in the processing of sensory information. In COVID-19 patients there is an inflammatory reaction of the nasal mucosa. Infected supporting cells of the nasal mucosa release molecules that activate the local antiviral innate immune response. In fact, macrophages spread inflammatory mediators, in particular TNF-η , IL-6 and IL-1. In this study we compared IL-6 levels with the degree of olfactory disorders and with the type of unperceived odour.Materials and methodsFrom 15 March to 30 November 2020 have been selected 82 patients (45 men age 62.3 ±14.2 and 37 women age 57.1± 12.8) with only smell dysfunctions were divided into mild and moderate patients. The evaluation of the smell disorder was carried out with a 14 questionnaire relating to the perception of domestic odorous: 6 questions for olfactory sensitivity (own perfume usually sprayed, oregano, olive oil, nutella, coffee aroma, orange juice) and 8 for olfactory-trigeminal sensitivity (alcohol, fish odor, vinegar, mint (gum), toothpaste, shampoo, cheese, ammonia).The IL-6 (v.n. 0 - 7 pg/ml) was measured with chemiluminescence assay using Cobas e801 (Roche Instrumentation). Statistical analyses were performed with Wilcoxon Rank test, and Mann-Whitney test (p <0.05). ResultsThe trigeminal and olfactory sensitivity are more compromised in moderate than mild patients (p <0.05). The statistically significant differences there were in IL6 levels in moderate versus mild patients when there was an impairment of trigeminal sensitivity (p <0.05). Conclusion In this study suggested that the smell disorders in Covid-19 patients couldn't be a deficit of the olfactory central nervous pathways but could be rather than mainly associated with the inflammatory process of the nasal mucosa and that deficit of the type of domestic unperceived odour ('olfactory' or 'trigeminal' sensitivity) could indicate the degree of severity of the disease.