Central and peripheral neurological involvement in monoclonal gammopathies of undetermined significance

Several studies have suggested a pathogenetic role of paraproteinaemias in PNS damage. Over the few last years, the presence of symptomatic or subclinical PNS lesions in CNS diseases like multiple sclerosis has been described. On the other hand, CNS demyelinating lesions and cervical atrophy have been reported in patients affected by chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Very few cases of MGUS associated with CNS disease alone or with both CNS and PNS disease have been reported. Since 1999, we have been studying 16 patients (8 M, 8 F), with a mean age 60.2 ± 13.4, affected by MGUS associated with symptomatic neurological central and/or peripheral diseases. Patients affected with lymphomas, lupus erithematosus and other immunological diseases were excluded. Involvement of both PNS and CNS was not associated to a particular type of paraproteinemia: monoclonal IgM were found in 8 patients; monoclonal IgG in 6 patients and monoclonal IgA in 1 patient and Ig in 1 patient. High antinervous system autoantibodies were found in 10/16 patients and antiMAG antibodies were detected in patients with paraproteinemic demyelinating neuropathy (PDN). High reactivity anti-nervous system might support the hypothesis of a pathogenetic role of MGUS in these neurological diseases. Nevertheless, at present, we cannot exclude that there is only a circumstantial association between MGUS and neurological damages, particularly concerning CNS.