Hello @doctorshelley, Welcome to Connect, an online community where patients and caregivers share their experiences, find support and exchange information with others. There is another discussion where @eoglover mentioned her husband has the FGFR3 antibody over 9000. I'm not sure what treatments have been used but she may be able to share more information.

-- FGFR3 ANTIBODY: https://connect.mayoclinic.org/discussion/fgfr3-antibody/

I also found a couple of articles that may provide some information for you.
-- Use of Intravenous Immunoglobulin in Small Fiber Neuropathy associated with FGFR3 (P2.433): https://n.neurology.org/content/90/15_Supplement/P2.433
-- Clinical features with anti fibroblast growth factor receptor 3 (FGFR3) antibody-related polyneuropathy: a retrospective study: https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-021-02090-2

Have you done any research into ketamine treatments?