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Polyneuropathy associated with IgG/IgA monoclonal gammopathy: a clinical and electrophysiological study of 15 cases

2003; Wiley; Volume: 10; Issue: 6 Linguagem: Inglês

10.1046/j.1468-1331.2003.00687.x

1468-1331

Laurent Magy, B. Chassande, Thierry Maisonobe, P. Bouché, J.‐M. Vallat, J.‐M. Léger,

Hereditary Neurological Disorders

Peripheral neuropathy has been widely reported in patients with monoclonal gammopathy (MG), more frequently immunoglobulin M (IgM) or IgG than IgA. Nevertheless, it remains unclear whether this association has clinical or pathogenic relevance. In order to clarify the possible role of IgG/IgA MG in neuropathy, we studied the clinical and electrophysiological features of 15 consecutive patients with polyneuropathy and IgG/IgA‐MG, and compared them to those of 40 patients with polyneuropathy associated with IgM‐MG, previously reported. Nine middle‐aged patients (60%) had a chronic progressive or relapsing demyelinating polyneuropathy (DP) that was clinically and electrophysiologically indistinguishable from classic chronic inflammatory demyelinating polyneuropathy (CIDP) and frequently responded to immunosuppressive treatments, both characteristics supporting a dysimmune process. Six older patients (40%) had a chronic axonal distal polyneuropathy similar to the so‐called chronic cryptogenic sensory polyneuropathy: there was no clear relationship with the MG in these patients and the response to immunosuppressive treatments was poor. Several features allowed us to distinguish between polyneuropathies associated with IgG/IgA‐MG (IgG/IgA‐PN) considered together and polyneuropathies associated with IgM‐MG (IgM‐PN). In the first group, the proportion of patients with a predominantly sensory clinical picture (27%) was less than that in the second group (75%), and there were fewer changes in nerve conduction studies. In addition, we found that the nine patients with DP associated with IgG/IgA‐MG (IgG/IgA‐DP) differed from the 31 with DP associated with IgM‐MG (IgM‐DP): clinical and electrophysiological studies clearly showed that the demyelinating pattern was more heterogeneous in IgG/IgA‐DP than in IgM‐DP. The spectrum of polyneuropathies associated with IgG/IgA‐MG is heterogeneous, including DP, which is similar to classic CIDP, and axonal polyneuropathy, in which the pathogenic role of the MG remains elusive. In addition, IgG/IgA‐DP differ from IgM‐DP on clinical and electrophysiological grounds, suggesting probable different physiopathological mechanisms.