How do you approach a patient with IgM monoclonal gammopathy associated with severe neuropathy of unclear etiology?

I usually confirm if the patient does not have AL Amyloidosis or POEMS, and as part of work up for IgM MGUS, I order MYD 88 mutation. If all are negative and I still believe that neuropathy is caused from his/her MGUS, you can try IVIG for the neuropathy as a trial (of course after using gabapentin,...

I think the gold standard is to do a sural nerve biopsy to look for monoclonal antibody mediated nerve damage. However, if other causes of neuropathy have been ruled out, I have empirically treated such patients without a biopsy. The goal is to prevent disability. Gabapentin and pregabalin just mask...