Background: In multifocal motor neuropathy (MMN), high dose of IV immunoglobulin (IVIg) is the only established treatment. Subcutaneous self-infusion with immunoglobulin G (IgG) (SCIG) increases patient autonomy and treatment flexibility, and might be associated with fewer side effects due to lower peak IgG levels. In a recent study of 9 patients with MMN, we reported that SCIG preserves muscle strength for a few months of treatment. Five patients preferred to continue SCIG after the trial and another patient chose to apply SCIG.
Methods: In this case series study of 6 IVIg-responsive patients with MMN on long-term SCIG maintenance therapy, a dose equivalent to their previous IVIg regimen was given for 2 years. Patients were evaluated before and after 3, 6, 9, 18, and 24 months of initiation of treatment using isokinetic strength examination of affected muscle groups, scores of neuropathy impairment and disability, and recording of side effects. The dosage of SCIG varied between 13 and 51 g per week, corresponding to a volume of 80 to 320 mL infused twice or thrice weekly.
Results: No major side events were reported, local skin reactions being mild and transient. The impairment and disability scores remained unchanged. Isokinetic muscle strength was stable with a median (range) 3.7% (-8.8 to 14.5) increase at follow-up.
Conclusion: Our study shows that long-term SCIG therapy is an alternative approach to IVIg that is desirable for some patients.
Classification of evidence: This 2-year follow-up study provides Class IV evidence of tolerability and safety in a small (n = 6) case series of patients with MMN preferring SCIG to IVIg.