Olfactory dysfunction in Multiple Sclerosis: A scoping review of the literature

Lucassen, Elisabeth B.; Turel, Anthony P.; Knehans, Amy; Huang, Xuemei; Eslinger, Paul J.

doi:10.1016/j.msard.2015.12.002

Cited by 45 publications

(40 citation statements)

References 36 publications

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“…A decreased odor threshold was found in patients with clinically isolated syndrome and early disease stages of RRMS, whereas odor discrimination and odor identification were more often affected in later disease stages. 3 A single study has reported olfactory assessments in patients with PPMS by testing odor identification alone and found mild impairment (13% affected). 7 We have now demonstrated a significantly worse olfactory function in PPMS as compared to RRMS and further provide a model that adjusts for the significant baseline differences in disease duration and EDSS to show that the differences are not merely reflective of general disease burden but seem to be particular to disease subtype.…”

Section: Discussionmentioning

confidence: 99%

“…3 A human autopsy cohort reported demyelination in parts of the olfactory pathway in 71% of pathologically confirmed MS cases. 8 Decreased olfactory bulb volume is correlated with increased MS lesion load in the olfactory brain, both of which are linked to impaired olfactory function.…”

Section: Discussionmentioning

confidence: 99%

“…3 The underlying pathophysiologic distinctives leading to PPMS vs RRMS are not well understood. Differences in the pattern of disease symptomatology may identify opportunities to better understand disease pathophysiology.…”

mentioning

confidence: 99%

“…Exploring for differences in olfactory dysfunction between PPMS and RRMS has been identified by other experts as a gap in the literature and potential area for future research. 3 As such, we sought to test the hypothesis that olfactory sense impairment is present in patients with PPMS, and that olfactory dysfunction is more severe in PPMS than in RRMS.…”

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confidence: 99%

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Olfactory dysfunction in patients with primary progressive MS

Schmidt

Maas

Geran

et al. 2017

Neurol Neuroimmunol Neuroinflamm

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Objective:We tested the hypothesis that olfactory function is more impaired in patients with primary progressive MS (PPMS) than that in relapsing-remitting MS (RRMS).Methods:Standardized olfactory testing was performed in 32 patients with PPMS, 32 patients with RRMS, and 32 healthy controls (HCs). Patients with olfactory dysfunction due to an alternative primary etiology were excluded. The validated olfactory testing method yielded individual scores for olfactory threshold, odor discrimination, and odor identification, along with a composite Threshold Discrimination Identification (TDI) score.Results:Olfactory dysfunction was identified in 27 (84%) patients with PPMS, 10 (31%) patients with RRMS, and 1 (3%) HC. While age and sex were similar between PPMS and HCs, the TDI score and all olfactory subscores were significantly worse in patients with PPMS compared with HCs (all p < 0.001). After adjustment for differences in age, sex, Expanded Disability Status Scale (EDSS), and disease duration, odor discrimination, odor identification, and the composite TDI score were worse in patients with PPMS vs RRMS (p = 0.03, 0.04, and 0.02, respectively). Neither age, sex, EDSS, nor disease duration was significantly associated with the composite TDI score.Conclusions:Olfactory dysfunction was more frequent and severe in PPMS compared with RRMS, independent of disease duration and overall disability status. Further research on cellular level differences in olfactory neural pathways may lead to new insights about disease pathogenesis in MS.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Olfactory dysfunction in patients with primary progressive MS

Schmidt

Maas

Geran

et al. 2017

Neurol Neuroimmunol Neuroinflamm

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show abstract

“…Different trials found an incidence of 15%, 22% and 38.5% when compared to healthy controls 3,8,9 . In a recent systematic review of the literature 10 searching for olfactory dysfunction in MS patients, forty articles were analyzed and pointed out a variability in reported frequency, but suggested a prevalence of olfactory dysfunction in 20% to 45% of MS population. The disagreement among investigators may arise from different testing methods, small size of the samples, heterogeneity of the study design but it can also be influenced by corticosteroid treatment as smell function can improve during remission and worsen during relapses.…”

mentioning

confidence: 99%