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A Free-breathing fMRI Method to Study Human Olfactory Function
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Olfactory dysfunction in patients with primary progressive MS

Felix A Schmidt1, Matthew B Maas1, Rohat Geran1

  • 1Clinical and Experimental Multiple Sclerosis Research Center (F.A.S., R.G., H.K., K.R., F.P., L.H.), Department of Neurology, NeuroCure Clinical Research Center (F.A.S., F.P.), Department of Psychiatry (C.S.), Department of Audiology and Phoniatrics (Ö.G.), Charité-Universitätsmedizin Berlin (F.P.), Germany; Department of Neurology (M.B.M.), Feinberg School of Medicine, Northwestern University, Chicago, IL; MSB Medical School Berlin (H.K.), Germany; and Experimental and Clinical Research Center (F.P.), Max Delbrück Center for Molecular Medicine, Berlin, Germany.

Neurology(R) Neuroimmunology & Neuroinflammation
|June 23, 2017
PubMed
Abstract

Insights

Patients with primary progressive multiple sclerosis (PPMS) experience more severe olfactory dysfunction than those with relapsing-remitting multiple sclerosis (RRMS). This impairment is independent of disease duration and disability.

Area of Science:

  • Neurology
  • Neuroscience
  • Olfactory research

Background:

  • Olfactory dysfunction is a potential early symptom in multiple sclerosis (MS).
  • The impact of different MS subtypes on olfactory function requires further investigation.

Purpose of the Study:

  • To compare olfactory function between patients with primary progressive multiple sclerosis (PPMS) and relapsing-remitting multiple sclerosis (RRMS).
  • To assess the prevalence and severity of olfactory dysfunction in PPMS versus RRMS.

Main Methods:

  • Standardized olfactory testing, including threshold, discrimination, and identification, was conducted in 32 PPMS patients, 32 RRMS patients, and 32 healthy controls (HCs).
  • Exclusion criteria targeted patients with alternative causes of olfactory dysfunction.
  • A composite Threshold Discrimination Identification (TDI) score was calculated.

Main Results:

  • A high prevalence of olfactory dysfunction was observed: 84% in PPMS, 31% in RRMS, and 3% in HCs.
  • Patients with PPMS showed significantly worse olfactory function (TDI score and subscores) compared to HCs (p < 0.001).
  • After adjusting for age, sex, EDSS, and disease duration, PPMS patients still exhibited worse odor discrimination, odor identification, and TDI scores than RRMS patients (p = 0.02-0.04).

Conclusions:

  • Olfactory dysfunction is more frequent and severe in PPMS compared to RRMS.
  • These olfactory deficits in PPMS are not explained by disease duration or disability (EDSS).
  • Investigating cellular differences in olfactory pathways may elucidate MS pathogenesis.

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