Short and long-term effect of IVIg in demyelinating neuropathy associated with MGUS, experience of a monocentric study.

BACKGROUND

The optimal treatment for demyelinating neuropathy associated with MGUS and anti-MAG neuropathy is not known.

METHODS

We retrospectively studied the efficacy of IVIg in 14 patients with DN-MGUS (seven IgM and seven IgG/A) and seven with anti-MAG neuropathies, treated in our reference center between 2002 and 2007. Patients were clinically evaluated before the first infusion, after the first infusion, and after the last IVIg treatment.

RESULTS

Anti-MAG neuropathy: after a single infusion, one patient improved and six were stable. At last follow-up (mean: 15.6months [range: 3.5-31], mean number of IVIg courses: 8 [2-33]), one patient maintained her improvement from baseline. DN-MGUS: after a single infusion, nine patients improved (64%), four were stable and one deteriorated further. The factor predictive of short-term response to IVIg was relapsing neuropathy responding better in the walking score analysis (Fisher exact test: P=0.005). At last follow-up (mean: 22.6months [range 2-72], mean number of IVIg courses: seven [1-24]), neurological status improved in four patients, five patients remained stable, including three who are still under regular IVIg, and four had deteriorated. Improvement from baseline persisted for a prolonged period in two patients after IVIg were stopped. Patients who were responders on Norris after the first IVIg course were significantly better responders at long-term follow-up than the others (P=0.001). We report no serious adverse effect.

CONCLUSION

IVIg are not very efficient in the management of anti-MAG neuropathies. Nevertheless, they have a frequent short-term beneficial effect in DN-MGUS, which was maintained at long-term follow-up in one-third of our patients. When a DN-MGUS patient is regularly treated by IVIg courses, frequent periodic clinical evaluations must be performed to determine when to stop treatment and switch to another one.