I've heard about a few people on the forums who have lost their sense of smell (not sure if it was permanent, or temporary), and have read about that as well ...

"Other less common causes of smell loss include chronic alcoholism (Shear et al., 1992), epilepsy Kohler et al., 2001), Kallmann's syndrome (Hudson et al., 1994), Korsakoff's psychosis (Mair et al., , pseudohypoparathyroidism (Doty et al., 1997a) and a number of common neurological disorders, including multiple sclerosis (Doty et al., 1997b, 1999"

http://www.nidcd.nih.gov/health/statistics/smell.asp

More commonly (although not much more), I've heard of PwMS who smell things that aren't there, like smoke, raw sewage, chemicals, boiling meat, etc.

Cherie