Go to page 5 of this 124 page link. You will see the study by Dr Rakocevic of 57 patients where he described their decline. No patients were on immunological therapy, which I assume means meds like IVIG.. He studied them for 2 years and followed some for up to 8 years. They were, though, on symptom management meds, which I assume means muscle relaxants.
This to me raises an ethics question. It does not seem right to observe patients seriously declining over a couple years time when there are no therapies that can help.
http://www.aanem.org/AANEMNew/media/...-file-size.pdf