IVIg for Small Fiber Neuropathy With Autoantibodies TS-HDS and FGFR3

The objective of this study is to develop a rationale for the selective treatment of small fiber neuropathy with immune globulin (IVIG) in the appropriate patients. The investigators hypothesize that individuals with auto-antibodies targeting neuronal antigens (TS-HDS and FGFR3) and confirmed evidence of small fiber neuropathy (by skin biopsy analysis of intra-epidermal nerve fiber density) will have an improvement in both nerve fiber density and pain after treatment with immune globulin. The co-primary endpoints will be a change in neuropathic pain (by VAS pain score) and a change in intra-epidermal nerve fiber density (by punch skin biopsy). The data gained from this pilot study will establish a rationale, with an appropriate screening test, for the use of immune globulin for the treatment of small fiber neuropathy.