To check it out...all the symptoms, diagnosis tests and treatments. I know many folks who have MMN who respond very well to IVIG but don't require it every month...some 2-3 months, some more often. And, depending on the type of neuropathy it is....other therapies seem to help for some folks.
Better to get it checked out while you are covered under insurance! I know that some folks from down under have had beastly times working thru their health system to get diagnosis and treatments.
As for any affect/effect on a permanent residency status? Gee, dunno...here I'd suggest seeing an immigration type attorney or the like-they mite have more insight about such things. Better to know beforehand what you mite be getting into before comitting one way or the other for the long term.
DO check things out tho! Overall your health will be better for it and you might be able to forestall additional weaknesses. That is the goal, isn't it?
Good thoughts and hopes - j