I'm glad to hear you are already taking Plaquenil. You should consider the steroid trial. It will help determine the inflammatory nature of this and if the steroids will help. You will definitely know one way or the other within 8 weeks (probably less time).

The IVIG will be an option for you in the future. It is not uncommon (or unreasonable) to have you do the steroids first. IVIG is extremely expensive and all other options should be tried first (my IVIG runs well over 30,000/month).

Keep in mind that if the steroids help and you continue with a longer term course, you can repeat the skin biopsy and determine if it has increased nerve fiber density or show positive changes in morphology. Of course, this can also be done after a 6 month course of IVIG for the same reason. This is one of the best attributes of the skin biopsy...repeat testing to gauge improvement/progression.

Hopefully your rheumy will reconsider the autoimmune aspect of this and treat accordingly. I think your making the right choice. Keep us posted please.