How are monoclonal gammopathy and neuropathy associated?
Approximately 10% of peripheral neuropathies are associated with serum monoclonal gammopathy (M-protein).
Two-thirds of such cases are initially classified as monoclonal gammopathy of uncertain significance (MGUS), but the remaining one-third, in decreasing frequency, are identified as multiple myeloma, amyloidosis, Waldenström macroglobulinemia, lymphoma, and leukemia.
Of the patients with MGUS and neuropathy, the risk of ultimately developing an identifiable cause of the paraprotein (e.g., a hematologic malignancy) is 25%.
Neuropathies associated with MGUS are a heterogeneous group that includes symmetric polyneuropathy, mononeuritis multiplex, isolated mononeuropathy, and cranial nerve palsies.
While IgG forms the most common M-protein (74%) in patients with MGUS, in patients with MGUS and neuropathy,
IgM is more common (48% vs 37% IgG and 15% IgA) and the best characterized.
