Olfactory bulb and brain volume may provide valuable information about olfactory dysfunction in patients with MS.
HONOLULU—A correlation between decreased olfactory bulb and brain volume and multiple sclerosis (MS) lesions may help to explain olfactory dysfunction among patients with MS, according to research presented at the American Academy of Neurology’s 63rd Annual Meeting.
Noting that olfactory dysfunction can occur in patients with MS, Felix Alexander Schmidt, a medical student at the Department of Neurology, University Hospitals Charité in Berlin, and colleagues investigated the reasons for the problem and the best ways of detecting it. They determined and compared objective olfactometry, olfactory bulb volume, olfactory brain volume, and number and volume of lesions in the olfactory brain in patients with MS.
Their study, which was also published in the May 17 online PLoS One, included 34 patients (24 women), ages 22 to 64, with MS and 30 healthy controls matched by age, sex, and smoking habits. Participants’ olfactory bulb volume, olfactory brain volume, and plaque load were assessed with use of MRI. The researchers performed orthonasal olfactory testing using the Threshold-Discrimination-Identification test, and they determined objective olfactometry by measuring Olfactory-Evoked-Potentials. Participants also were given the Expanded Disability Status Scale (EDSS) test.
Olfactory dysfunction was present in 41% of patients with MS and 8% of the control group. The researchers found hyposmia in 71% of patients with a decreased olfactory bulb volume (<100 mm3) and 83% of patients with a decreased olfactory brain volume (<30,000 mm3). Decreased olfactory bulb volume was correlated with objective olfactometry, as well as with the number and volume of MS lesions in the olfactory brain. In addition, decreased olfactory brain volume was correlated with the volume of lesions in the olfactory brain and EDSS scores. Patients’ scores on the Identification subtest of the Threshold-Discrimination-Identification test were correlated with their EDSS scores, latest relapsing phase, and disease duration.
“The correlation between a higher number and volume of lesions in the olfactory brain with a decreased olfactory bulb and olfactory brain volume could help to explain olfactory dysfunction in MS patients,” the researchers concluded. “The correlation between volumetric measurements and objective olfactometry results shows that olfactory bulb and olfactory brain volume may provide valuable information about olfactory function in MS patients. Hyposmia seems to appear more frequently in an early stage of disease. The Identification subtest was especially sensitive in detecting olfactory changes in MS patients.”
—Jack Baney