Subcutaneous immunoglobulin therapy for multifocal motor neuropathy.

The objective of this study was to investigate whether subcutaneous immunoglobulin (SCIg) treatment is feasible and safe in maintaining muscle strength of patients with multifocal motor neuropathy (MMN). Patients fulfilling the EFNS/PNS criteria for definite MMN treated with intravenous immunoglobulin (IVIg) were switched to weekly SCIg in a single-center, open-label pilot intervention study. The first group of patients started with a SCIg dose equivalent to 50% of the IVIg maintenance dose. In case of deterioration, patients received a loading dose of IVIg and doubling of SCIg dose. The second group started with a dose equivalent to the IVIg maintenance dose. Primary outcome was the Medical Research Council (MRC) sum score from 10 muscle groups. Secondary outcomes were grip and pinch strength, dexterity, disability, quality of life, adverse events, and serum immunoglobulin concentrations. Ten patients were included, five in both groups. In the first group, one patient withdrew informed consent due to local adverse events, four deteriorated. In the second group, four out of five patients maintained muscle strength with SCIg during the 6 months follow-up. Local adverse events were frequent, especially during first weeks of treatment, but generally well tolerated. Seven mild systemic adverse events were reported, all but one in the first week of treatment. In some, but not all MMN patients in this study, SCIg therapy was feasible and safe and maintained strength as well as IVIg. SCIg may be a viable alternative maintenance therapy in some patients with MMN currently receiving IVIg.