Evaluation of the sense of taste and smell in patients with Neurofibromatosis Type 1

Abstract

Objective: The objective of this study was to determine if patients with Neurofibromatosis Type 1 (NF1) have an impaired sense of smell or taste. Neurofibromin, the NF1gene protein product is ubiquitous in the body and is especially associated with the development of neurogenetic structures. Lately enlarged olfactory bulbs have been described in patients with NF1. Until now, there is no study to evaluate the sense of smell and taste in patients with NF1.

Method: This study has been approved by the Hamburg Ethics committee. An evaluation of the sense of smell and taste was undertaken in 26 patients with NF1 using the Burghart Sniffin' Sticks. Three patients were excluded due to a prior infection with the Corona virus. As a control group the same examination was performed in healthy individuals (same sex/ same age as the NF1 patients) by the same examiner.

Results: The results show a normal sense of smell in patients with NF1. The morphologic finding of enlarged olfactory bulbs seem to have no functional equivalent. However, 8 out of 23 patients with NF1 had difficulties identifying at least one taste flavor. In total 9.8% of possible taste qualities were misidentified. In the healthy control group, all taste qualities were identified correctly. Considering each taste quality as separate case, a significant difference in the taste function was identified based on Fisher's exact test (p=0.003).

Conclusion: The current study does not show a correlation between NF1 and an impaired sense of smell. Yet significant reduction in the sense of taste was found in the patients with NF1. Further research will have to be conducted to find the underlying causal pathways.

Clinical relevance: NF1 is recently being acknowledged not only for its' macroscopic aesthetic and functional impairments, but also as a neurodevelopmental disorder. Evaluating the neural structures in regard to their function is a first step in understanding more about the disease.

Keywords: N. olfactorius; Neurofibromatosis; intraoral; smell; taste; tongue.