Specific smell dysfunctions in relapsing-remitting multiple sclerosis

The present study assessed odour threshold, discrimination and identification in relapsing-remitting MS (RRMS) patients. We administered the Sniffin’ Sticks Extended Test (Burghart Messtechnik GmbH, Wedel, Germany) to 50 RRMS female patients and to 50 matched control subjects. Also, the number and the volume of MRI-visible demyelinating plaques within the inferior frontal and temporal lobes (IFTL complex), were quantified in a patient subgroup. The results indicated that up to 34% of the RRMS sample exhibited hyposmia, but none of the MS patients could be considered functionally anosmic. Odour identification and general olfactory performance signifi cantly decreased with respect to the patients’ age. No significant correlations between olfactory scores and the number and the volume of plaques within the IFTL complex were found. These findings suggest that some specific forms of olfactory dysfunction do exist in MS patients and that the correlation between olfactory dysfunctions and structural brain damage might not be as strict as previously suggested.