Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. X:X | DOI: 10.5507/bp.2025.021

Diagnostics of olfactory dysfunction in Parkinson's disease - a literature overview and case series

Libor Vasina1, 2, Nikola Pastorkova3, Oleksii Vorobiov2, 4, Karla Janouskova2, 4, Petra Dytrych5, 6, Jiri Hlozek2, 4, Sarka Musilova3, Jaromir Astl2, 4, Richard Holy2, 4
1 Department of Neurology, Military Hospital Brno, Brno, Czech Republic
2 Third Faculty of Medicine, Charles University, Prague, Czech Republic
3 Department of Neurology, Military University Hospital Prague, Prague, Czech Republic
4 Department of Otorhinolaryngology and Maxillofacial Surgery, Third Faculty of Medicine, Charles University and Military University Hospital Prague, Prague, Czech Republic
5 Department of Ear, Nose and Throat, University Hospital Motol, Prague, Czech Republic
6 Second Faculty of Medicine, Charles University, Prague, Czech Republic

Olfactory dysfunction is increasingly recognised for its predictive value as an early indicator of a number of degenerative neuropathologies including Parkinson's Disease (PD). In this overview, we cover the relationship between PD and olfactory dysfunction (OD). Prodromal premotor symptoms of PD include sleep disturbances, psychiatric disorders, constipation and OD. The latter can precede motor symptoms by several years and its occurrence is frequent in Parkinson s disease with a prevalence that can range from 45%-90%. Olfactory perception in these cases can be tested using subjective and objective methods. Commonly used psychophysical tests in the Czech Republic include Sniffin' Sticks Tests and the Odorized Marker Test but these may be inaccurate and demanding on patients with cognitive deficits in addition to motor symptoms. For these reasons, objective electrophysiological olfactory tests that depend on olfactory/trigeminal event-related potentials (OERPs/TERPs) for example are more useful. In this paper we describe a series of case reports, demonstrating the importance of comprehensive olfactory examination. The significance of objective electrophysiological olfactory/ trigeminal tests in the diagnosis of PD, is underscored given the rising incidence of this condition and the need for early diagnosis.

Keywords: Parkinson's disease, olfactory dysfunction, olfactory test, Sniffin' Sticks, OERPs, TERPs

Received: March 27, 2025; Revised: July 10, 2025; Accepted: July 10, 2025; Prepublished online: August 13, 2025 

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