Olfactory dysfunction is common in multiple sclerosis

[MSUK]

Olfactory Pathology in Central Nervous System Demyelinating Diseases.

DeLuca GC, Joseph A, George J, Yates RL, Hamard M, Hofer M, Esiri MM.

Abstract

Olfactory dysfunction is common in multiple sclerosis (MS). Olfactory bulb and tract pathology in MS and other demyelinating disease remains unexplored.

A human autopsy cohort of pathologically confirmed cases encompassing the spectrum of demyelinating disease (MS; n=17), neuromyelitis optica (NMO); n=3), and acute disseminated encephalomyelitis (ADEM); n=7)) was compared to neuroinflammatory (herpes simplex virus encephalitis (HSE); n=3), neurodegenerative (Alzheimer's disease (AD); n=4), and non-neurologic (n=8) controls.

For each case, olfactory bulbs and/or tracts were stained for myelin, axons, and inflammation. Inferofrontal cortex and hippocampus were stained for myelin in a subset of MS and ADEM cases.

Olfactory bulb/tract demyelination was frequent in all demyelinating diseases (MS 12/17 (70.6%); ADEM 3/7 (42.9%); NMO 2/3 (66.7%)) but was absent in HSE, AD, and non-neurologic controls.

Inflammation was greater in the demyelinating diseases compared to non-neurologic controls.

Olfactory bulb/tract axonal loss was most severe in MS where it correlated significantly with the extent of demyelination (r=0.610, P=0.009) and parenchymal inflammation (r=0.681, P=0.003).

The extent of olfactory bulb/tract demyelination correlated with that found in the subjacent adjacent inferofrontal cortex but not hippocampus.

We provide unequivocal evidence that olfactory bulb/tract demyelination is frequent, can occur early and be highly inflammatory, and is specific to demyelinating disease.

Source: Brain Pathol. 2014 Sep 17. doi: 10.1111/bpa.12209. [Epub ahead of print] & Pubmed PMID: 25230202 (22/09/14) http://www.ms-uk.org/myelin