If he's qualified [CDL if required, and it usually is], then it's a question of whether he thinks he can do the work, and whether you [and a carrier] agree.
More specifically, it's a question of whether the doctor performing the examination thinks he can do the work. Drivers must be medically qualified to not only drive the vehicle safely, but also to do pre and post trip safety inspections, secure the load and make sure it has not shifted. There are a few specific medical conditions that prevent you from obtaining a CDL, but MS isn't one of them. It all depends on whether you can physically perform the work.