My husband has nurofascin 140 positivity & he had 2 rounds of ivig before the nurofascin positivity test, they didnot help him much , but they have planned a plasma exchange also called plasma pherasis for him at the end of this month because for him the auto immune condition kept prigressiing without any doctor testing him for nurofascins for more than a year. What is your son getting the ivig for? I think they will first do a plasma pherasis to remove the antibodies from the blood and then give him ivig