Heterogeneity of Polyneuropathy Associated with Anti-MAG Antibodies.

Laurent Magy,Karima Ghorab,Jean-Michel Vallat,Christiane Caudie,Stéphane Mathis,Prisca Lebeau,Raphaël Kaboré

doi:10.1155/2015/450391

Abstract

Polyneuropathy associated with IgM monoclonal gammopathy and anti-myelin associated glycoprotein (MAG) antibodies is an immune-mediated demyelinating neuropathy. The pathophysiology of this condition is likely to involve anti-MAG antibody deposition on myelin sheaths of the peripheral nerves and it is supposed to be distinct from chronic inflammatory demyelinating neuropathy (CIDP), another immune-mediated demyelinating peripheral neuropathy. In this series, we have retrospectively reviewed clinical and laboratory findings from 60 patients with polyneuropathy, IgM gammopathy, and anti-MAG antibodies. We found that the clinical picture in these patients is highly variable suggesting a direct link between the monoclonal gammopathy and the neuropathy. Conversely, one-third of patients had a CIDP-like phenotype on electrodiagnostic testing and this was correlated with a low titer of anti-MAG antibodies and the absence of widening of myelin lamellae. Our data suggest that polyneuropathy associated with anti-MAG antibodies is less homogeneous than previously said and that the pathophysiology of the condition is likely to be heterogeneous as well with the self-antigen being MAG in most of the patients but possibly being another component of myelin in the others.

Highlights

Ten percent of patients with a polyneuropathy of unknown cause have a monoclonal gammopathy [1]
The data from all patients with a polyneuropathy associated with an IgM monoclonal gammopathy and anti-myelin associated glycoprotein (MAG) antibodies seen in our neurology department over the previous 25 years were retrospectively reviewed
We have described a series of patients with polyneuropathy associated with IgM monoclonal gammopathy and antiMAG antibodies

Summary

Introduction

Ten percent of patients with a polyneuropathy of unknown cause have a monoclonal gammopathy [1]. When nerve biopsy is performed, it shows signs of demyelination on semithin sections and teased fiber studies, and electron microscopic examination usually displays the classic pattern of widening of myelin lamellae (WML), which is considered the pathological hallmark of the disease [7]. This latter feature corresponding to deposits of the monoclonal IgM on myelin sheath distinguishes pathologically anti-MAG neuropathy from chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) [8]

Results

Discussion

Conclusion