Supplementary Material for: Small Fiber Neuropathy Triggered by COVID-19 Vaccination: Association with FGFR3 Autoantibodies and Improvement during Intravenous Immunoglobulin Treatment

Multiple case series have demonstrated the emergence of small fiber neuropathy following acute coronavirus disease 2019 (COVID-19) infections. Further, one large case supports that the COVID-19 vaccine has been reported to result in small fiber neuropathy. We report a case of a patient with confirmed small fiber neuropathy post-COVID-19 vaccination with positive FGFR3 antibodies. The effect of intravenous immunoglobulin (IVIG) has been recently explored for treatment of presumed autoimmune small fiber neuropathy. To our knowledge, this is the first published case report of COVID vaccination-induced FGFR3-associated small fiber neuropathy improving in the context of IVIG administration as demonstrated by normalization of small fiber density measured by skin biopsy accompanied by marked improvement in the patient’s symptoms.