CIDP and have gone thru the whole cookbook of tests to get that precious diagnosis.
I suggest you take a look at the following web sites and get oriented first to understand what all is happening to your body:
This is a doctors' way of diagnosing Peripheral Neuropathy, don't discount it, as it describes all the tests that eliminate PN and a whole slew of other stuff to get to the MMN diagnosis..[besides feeling like @#*$!]
http://www.aafp.org/afp/980215ap/poncelet.html
Usually for PN folks, the MMN is diagnosed at somewhere in the 'middling' stage of tests...I think

Another diagnostic resource was put together by a PN member along with other members' input. It outlines over 96% +/- of all tests that could be done to diagnose PN, autoimmune diseases [CIDP {my issue} and MMN {your issue}] and other neuro aspects that overlap. http://www.lizajane.org/
To help you keep track of it all, tho...you have to get copies of all your tests. A frustrating thing true, but very useful if you have to move or for a heap of other issues as well.

One excellent resource is a magazine published w/help from IVIG manufacturers called IG Living. www.igliving.com Suscribe to the 'e-zene' an on-line magazine and save trees but you have all access to past issues. It's chock full of info about all folks who use IVIG for immune diseases. It's a free resource and I have personally found the folks there helpful to me and to many others who have problems getting their IVIG for all sorts of reasons...They also answer all sorts of questions, be they simple ones or complicated ones. They are great!

This is from an international association about CIDP pain [my problem] but it is useful in terms of explaining what is happening to your immune system...
http://www.cidpinfo.com/about_this_site/site_map.aspx
Also about the whole diagnosis 'menu' that consists of a sort of checklist of 'things' that have to be eliminated before deciding it's MMN or 'something else'.

This is the whole menu of neuro issues in a somewhat technical format:
http://neuromuscular.wustl.edu/ It does help outline the distinctions between MMN and other neuro/neuropathy issues -many many overlap. You might need access to a medical dictionary for this one, but it is a goldmine of info in terse format.

After you read all that, and aren't cross-eyed, I encourage you to check out the 'Peripheral Neuropathy' forum -
http://neurotalk.psychcentral.com/forum20.html
It's interesting because we all seem to have 'other' medical issues as well. And are a curious and frustrated bunch.

As for Info on IVIG, I've found that the IGLiving source is a truly reliable source for info about it. I have also met and grown to appreciate many folks who receive IVIG for MMN, I have received IVIG for over 3 years for my CIDP and KNOW I am soo much better for it!

IF you have any questions about getting and receiving IVIG, please don't hesitate to ask...either post here or thru a PM... It IS important that you be thoroughly informed about the IVIG; How it's put into you; the side effects, good and bad; and the safeguards and safety of it all. It is very special stuff! It can make a biig difference in your life and I truly hope that is what happens in your case...you get a bit of your LIFE back! I truly hope this all helps...I've got lots more info if you want it... - j