Naltraxone, the N in LDN, is a drug that is approved by the FDA to treat some illness(s?) OTHER than MS. Some folks have found it helpful in Low Doses, (The L and D in LDN). If you do a google search you'll find TONS of information about it. Seems like there is one doctor who tried it on some of his patients, some of them had some good symptom relief, he spread the word on the net, and many folks now try it. You have to find a pharmacist willing to make it up (compound it), because it doesn't come in a conventional or standard form. Some doctors who are open to alternative/complementary medicines will be wiling to prescribe it; others won't.
Supposedly it can be taken with one of the CRABS -- I think Copaxone, but I may be wrong. I'm sure one of the believers in the drug will be along to make all the corrections necessary in this post.
The National MS Society has agreed to (at least in part) sponsor a legitimate double-blind study of the compound to see if there is any benefit to it, but that study hasn't gotten underway yet (or if it has, it isn't complete.)
People who take it swear that it helps with symptoms, and slows progression. But of course all their reports are anecdotal - -not backed up by any legitimate research. And there's no way of knowing how many folks have tried it without any benefit.
It apparently is cheap -- around $35 a month -- if you can get the prescription and find a pharmacy willing to concoct it for you.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....