First, you may want to cut and paste your post into a separate new post, as that might get more attention and responses – however, I’m happy to reply here.
For me, IVIG has never provided a rapid turnaround, however it does a reasonably good job of keeping the basic progression slowed. My case of CIDP is the Lewis-Sumner or MADSAN variant. It is somewhat slowly progressive, asymmetric and primarily motor (about 1/3 sensory) that has been marked by one very severe and acute exacerbation that lasted well over six months and has left me severely disabled for the past 18 months. This exacerbation raged despite a battery of treatments. Finally, an aggressive combination of plasma exchange and IVIG nipped it and with time I recovered strength. Give the IVIG time, as your wife’s neurologist suggests. Maybe she should receive treatment for pain as well?
Her symptoms, and the time-frame of their development certainly sound like CIDP. I know that in more slowly progressing cases, such as mine, there is the thought of underlying malignancies of the blood or lymphatic system that may be at play, but it seems more rapidly developing cases such as hers are not as likely to be a result of that?
Anyhow – best of luck to you and your wife.