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| Poster #274 Olfactory-Trigeminal Interactions in Parkinson's Disease Compared to Others Forms of Olfactory Dysfunction |
| Sarah Brosse1, Olivier Fortier-Lebel2, Emilie Hudon2, Johannes Frasnelli1,3 1Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada 2Department of Psychology, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada 3Research Center of the Sacré-Coeur Hospital of Montreal, Montreal, QC, Canada |
Olfactory dysfunction (OD) is a common early symptom of Parkinson’s disease (PD), but is not specific to this condition, as approximately 20% of the general population also experience various forms of OD. Distinguishing PD-related OD from non-Parkinsonian OD (NPOD) is crucial for the use of olfactory measures in early screening. In this context, the trigeminal system—a chemical sense involved in the perception of freshness, pungency, pain, tickling, and burning when exposed to odorants—is of particular interest due to its close interconnection with the olfactory system. These systems suppress and/or enhance each other, and this interaction appears specifically altered in PD compared to NPOD. To better understand these interactions, our study evaluated how olfactory co-stimulation influences the localization of a pure trigeminal stimulus (CO2) in 18 PD patients, 20 NPOD patients, and matched control groups with a normal sense of smell. We used an olfactometer to deliver stimuli under four conditions: a lateralization test with pure CO2, with pure phenyl ethanol (PEA), with ipsilateral co-stimulation of CO2 and PEA in the same nostril, and with contralateral co-stimulation of CO2 and PEA in opposite nostrils. Brain activity was recorded using electroencephalography (EEG). Ipsilateral, but not contralateral, olfactory co-stimulation with a pure odorant improved the ability to localize a trigeminal stimulus in all groups (p<0.05). Ongoing analyses of evoked potentials will further explore these interactions at the central level. To conclude, the presence of PEA facilitates trigeminal responsiveness. |