Long-term follow-up of facilitated subcutaneous immunoglobulin therapy in multifocal motor neuropathy

Objective: To assess the feasibility, efficacy and patient satisfaction of long-term facilitated subcutaneous immunoglobulin therapy (fSCIG) in multifocal motor neuropathy (MMN). Methods: Twelve patients previously participating in a randomized trial investigating the short-term efficacy of fSCIG were offered to switch to fSCIG maintenance therapy following a variable interval on conventional subcutaneous immunoglobulin. Results: Eight patients were switched to fSCIG maintenance therapy, seven of whom were invited for a follow-up assessment after 18 months (range 13-23 months) of treatment. The age at follow-up was 57 years (range 45-70 years) and patients received a median weekly dose immunoglobulin G of 32.5 g (range 20.0-50.0 g), the dose being unaltered compared to baseline values following completion of the fSCIG trial. In five patients the infusion was biweekly, whereas two patients were infused weekly. The follow-up mean isometric strength normalized to pre-trial values was 107.7% (95% CI 86.4-129.0%) being non-inferior to baseline values (104.7%, 95% CI 97.6-111.8%, P = 0.015). The mean ODSS was 2.0 (95% CI 0.8-3.2) which is identical to the baseline score following completion of the fSCIG trial, the P-value for non-inferiority being <0.0001. The secondary variables of impairment, function and quality of life at follow-up all were non-inferior to baseline values (P <= 0.046). Conclusion: fSCIG seems feasible and effective for long-term maintenance treatment in patients with MMN.