Prognosis of polyneuropathy due to IgM monoclonal gammopathy: a prospective cohort study

Neurology. 2010 Feb 2;74(5):406-12. doi: 10.1212/WNL.0b013e3181ccc6b9.


Background: The disease course of polyneuropathy associated with immunoglobulin M monoclonal gammopathy (IgM MGUSP) can be highly variable. In order to identify factors that influence long-term disease outcome, a prospective cohort study was performed of 140 patients with IgM MGUSP over a period of 23 years.

Methods: All patients with IgM MGUSP who were diagnosed in our tertiary referral center for polyneuropathy were eligible. All patients underwent nerve conduction studies and were tested for anti-MAG antibodies. The modified Rankin Scale, graded muscle strength, quantified sensory function, and laboratory testing were performed at 0, 1, 2, and 5 years and at last visit. The primary outcome measure was the risk of developing a modified Rankin Scale score of > or = 3 points.

Results: A total of 140 patients with IgM MGUSP fulfilled inclusion criteria (101 [72%] demyelinating, 39 [28%] axonal, 63 [44%] MAG positive). The median age at onset was 59 years (interquartile range 52-67), median disease duration at baseline was 3.2 years (interquartile range 1.9-6). Anti-MAG antibodies were associated with a lower risk of Rankin Scale score > or = 3. Demyelination and a higher age at onset were associated with a higher risk for Rankin Scale score > or = 3. Based on these 3 factors, a Web-based prognostic model was developed that directly allows clinicians to estimate the probability of developing disability (

Conclusion: Higher age at onset and demyelination increase the risk, whereas anti-MAG antibodies decrease the risk, of developing Rankin Scale score > or = 3 in polyneuropathy associated with immunoglobulin M monoclonal gammopathy (IgM MGUSP). Our Web-based prognostic model allows determination of prognosis in IgM MGUSP.

MeSH terms

  • Aged
  • Bone Marrow / pathology
  • Cohort Studies
  • Demyelinating Diseases / complications
  • Disability Evaluation
  • Disease Progression
  • Electromyography
  • Female
  • Glycoproteins / blood
  • Glycoproteins / urine
  • Humans
  • Immunoglobulin M / immunology*
  • Immunotherapy / methods
  • Male
  • Middle Aged
  • Monoclonal Gammopathy of Undetermined Significance / complications*
  • Monoclonal Gammopathy of Undetermined Significance / therapy
  • Muscle Strength
  • Neural Conduction / physiology
  • Polyneuropathies / diagnosis*
  • Polyneuropathies / etiology*
  • Prognosis
  • Retrospective Studies
  • Severity of Illness Index
  • Statistics, Nonparametric


  • Glycoproteins
  • Immunoglobulin M
  • protein M (glycoprotein)