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

•Olfactory dysfunction can be frequently measured in MS patients.•Both threshold and identification deficits can be observed.•Correlations between olfactory dysfunction and cognitive dysfunction and depression/anxiety have been observed.•Olfactory dysfunction in MS correlates with disability as measured by the EDSS.•Measurements of olfactory dysfunction may wax and wane with relapses.