IVIG in the Treatment of Autoimmune Small Fiber Neuropathy with TS-HDS, FGFR-3, or Plexin D1 Antibodies

Inclusion Criteria:

1. Patients ≥ age 18

2. Patient with clinical and biopsy evidence of pure small fiber neuropathy (with orwithout dysautonomia) as evidenced by reduced IENFD on skin biopsy using PGP 9.5 asthe immunostain. Biopsy must have been performed within 12 months of studyenrollment, and using Corinthian Reference Laboratory (Benbrook, TX).

3. Patients must have elevated and/or abnormal titers of autoantibodies to TS-HDS-IgMor FGFR3-IgG or Plexin-D1, measured by the Washington University NeuromuscularLaboratory (St Louis) within 12 months of study enrollment.

4. Patients must have a baseline pain score on a visual analogue scale (VAS) of Greateror equal to 4/10

5. Patients must have a baseline Utah Early Neuropathy Scale (UENS) score of Greater orequal to 4/10

6. Small Fiber Neuropathy Screening List (SFNSL) score of 11/84 or greater

7. Non-pregnant, non-lactating female

8. Patients must be able to travel to Detroit, MI (USA) for the infusions, follow-upbiopsy, and other clinical activities; these will not be performed elsewhere

Exclusion Criteria:

1. Any other known cause for small fiber neuropathy other than the presence of theelevated titers of the novel auto-antibodies.

2. Patients with generalized, severe musculoskeletal conditions other than SFN thatprevent a sufficient assessment of the patient by the physician.

3. Electromyography/nerve conduction study (EMG/NCS) evidence of large fiberpolyneuropathy, to be confirmed by study PI

4. Underlying severe heart, kidney, liver disease, or HIV infection, (Note: If there isno previous HIV test result documented, a test may be performed in order to confirmeligibility)

5. Patients with a history of deep vein thrombosis within the last year prior tobaseline visit or pulmonary embolism ever; patients with susceptibility to embolismor deep vein thrombosis.

6. Known significant IgA deficiency with antibodies to IgA.

7. History of hypersensitivity, anaphylaxis or severe systemic response toimmuno-globulin, blood or plasma derived products, or any component of IVIG 10%,

8. Known blood hyperviscosity, or other hypercoagulable states,

9. Use of IgG products within six months prior to enrollment,

10. Patients with a history of drug or alcohol abuse within the past five years prior toenrollment,

11. Patients unable or unwilling to understand or comply with the study protocol