Intravenous immunoglobulin for chronic residual peripheral neuropathy in eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome): a multicenter, double-blind trial

Eosinophilic granulomatosis with polyangiitis (EGPA), previously called Churg–Strauss syndrome, frequently affects the peripheral nervous system. We conducted a multicenter, double-blind, three-arm treatment period, randomized, pre-post trial to assess the efficacy of intravenous immunoglobulin (IVIg) administration for residual peripheral neuropathy in patients with EGPA that is in remission, indicated by laboratory indices. Twenty-three patients were randomly assigned into three groups, in which the timing of IVIg and placebo administration was different. Each group received one course of intervention and two courses of placebo at 2-week intervals. Treatment effects were assessed every 2 weeks for 8 weeks. The primary outcome measure, the amount of change in the manual muscle testing sum score 2 weeks after IVIg administration, significantly increased (p = 0.002). The results over time suggested that this effect continued until the last assessment was done 8 weeks later. The number of muscles with manual muscle testing scores of three or less (p = 0.004) and the neuropathic pain scores represented by the visual analogue scale (p = 0.005) also improved significantly 2 weeks after IVIg administration. This study indicates that IVIg treatment for EGPA patients with residual peripheral neuropathy should be considered even when laboratory indices suggest remission of the disease.