Longitudinal Testing of Olfactory and Gustatory Function in Patients with Multiple Sclerosis.

Florian Cornelius Uecker,Hagen Kunte,Önder Göktas,Lutz Harms,Felix Alexander Schmidt,Christian Gerz,Heidi Olze,Fernando De Castro

doi:10.1371/journal.pone.0170492

Abstract

BackgroundThe aim of the study was to investigate changes of the olfactory and gustatory capacity in patients with multiple sclerosis (MS).Methodology20 MS patients were tested longitudinally for 3 years after initial testing. The Threshold Discrimination Identification test (TDI) was used for subjective olfactometry. Objective olfactometry was performed by registering olfactory evoked potentials (OEP) by EEG. The Taste Strip Test (TST) was used for gustatory testing.Results45% of the patients showed olfactory dysfunction in the follow-up TDI test and 50% showed delayed OEP´s. 20% of the patients showed gustatory dysfunction on follow-up visit. The patients showed mild disease activity with 0,3 ± 0,5 relapses over the testing period and no significant change of their olfactory and gustatory capacity. The olfactory capacity for the discrimination of odors correlated inversely with the number of relapses (r = -0.5, p ≤ 0.05). The patients were aware of their olfactory deficit.ConclusionsOlfactory and gustatory dysfunction is a symptom in MS patients and may be a useful parameter to estimate disease progression in MS patients. As the discrimination of odors is processed in higher central regions of the central nervous system (CNS), the results suggest that olfactory dysfunction could be due to CNS damage.

Highlights

Multiple Sclerosis (MS) is a chronic inflammatory disease affecting the central nervous system (CNS) and typically follows a relapsing-remitting disease course (RRMS)
Olfactory and gustatory dysfunction is a symptom in MS patients and may be a useful parameter to estimate disease progression in MS patients
As the discrimination of odors is processed in higher central regions of the central nervous system (CNS), the results suggest that olfactory dysfunction could be due to CNS damage

Summary

Introduction

Multiple Sclerosis (MS) is a chronic inflammatory disease affecting the CNS and typically follows a relapsing-remitting disease course (RRMS). 15% of all MS patients initially present with a primary progressive disease course (PPMS) characterized by constantly increasing physical disability without recovery. The neurological symptoms vary depending on the region of the brain that is affected by MS lesions [1,2]. Olfactory dysfunction mainly occurs with Alzheimers and Parkinsons disease and less frequently with other neurodegenerative diseases [3,4]. Olfactory dysfunction often presents as a first symptom of Parkinsons disease, occurring around 4–6 years before motor disorders begin [5,6]. Detecting olfactory disorders is becoming increasingly important in the research of neurological diseases [4].

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