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Characterization of neuropathies associated with elevated IgM serum levels
Adina R Goldfarb1, Howard W Sander, Thomas H Brannagan
1Peripheral Neuropathy Center, Department of Neurology, Weill Medical College of Cornell University, 635 Madison Ave., Suite 400, New York, NY 10022, USA. argoldfarb@juno.com
Journal of the Neurological Sciences
|February 8, 2005
Summary
Neuropathy associated with elevated immunoglobulin M (IgM) levels, whether monoclonal or polyclonal, often presents as demyelinating or multifocal. Quantitative IgM and immunofixation can help identify immune-mediated neuropathy.
Area of Science:
- Neurology
- Immunology
- Clinical Medicine
Background:
- Neuropathy associated with polyclonal IgM gammopathy is not well characterized, unlike IgM monoclonal gammopathies.
- Elevated serum IgM levels can be associated with various neuropathies.
Purpose of the Study:
- To characterize the clinical and electrodiagnostic features of neuropathy in patients with elevated serum IgM.
- To differentiate neuropathy phenotypes in monoclonal versus polyclonal IgM gammopathies.
Main Methods:
- Retrospective review of 45 patients with elevated quantitative IgM.
- Analysis of clinical phenotype, electrodiagnostic features (demyelination, focality), IgM monoclonal gammopathy, and autoantibody activity.
Main Results:
- Elevated IgM was found in 11.5% of patients; 53% had polyclonal and 47% had monoclonal gammopathy.
- Anti-nerve antibodies were more frequent in monoclonal (67%) vs. polyclonal (4%) gammopathy.
- 73% of tested patients met criteria for Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), with 92% in the monoclonal group and 59% in the polyclonal group.
Conclusions:
- Neuropathy in elevated IgM, with or without monoclonal gammopathy or autoantibodies, is often demyelinating or multifocal.
- Similar neuropathy phenotypes are observed in both monoclonal and polyclonal IgM gammopathies.
- Serum quantitative IgM and immunofixation aid in identifying immune-mediated or demyelinating neuropathy.