MMN is an immune-mediated demyelinating neuropathy that causes progressive, asymmetric weakness of the distal limbs with no objective sensory loss.1

Whom It Effects



Differential Diagnosis

Learn more about diagnosis and treatment of MMN:

  • MMN has historically been difficult to diagnose due to its similarity to other related diseases including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), Lou Gehrig's disease [amyotrophic lateral sclerosis (ALS)], lower motor neuron disease and Lewis-Sumner Syndrome2
  • MMN may also be misdiagnosed as nerve compression (entrapment neuropathy)2

Diagnostic criteria for MMNa

  • Asymmetric weakness of distal arm and/or leg muscles1,3,6,8
  • No objective sensory impairment3,8
  • Motor nerve conduction block in 2 or more nerves1,2,7,8,9
  • Axonal demyelination, damage and/or loss1,2,10
  • Anti-GM1 antibodies (present in over 50% of patients with MMN)1,9
  • Other tests that may be useful to confirm or exclude a diagnosis of MMN include MRI and CSF2

aMMN should be considered when patients present with asymmetric, distal muscle weakness with no objective sensory loss.

bEstablishing diagnosis based on consensus criteria for confirming conduction block may result in underdiagnosis, as conduction block is not always necessary for a diagnosis if other criteria are met

Not all patients exhibit all symptoms.


The importance of a timely diagnosis


In a retrospective case cohort analysis of 47 patients with MMN the mean symptoms duration prior to diagnosis was 6 years.
  • Mean time from symptom onset to diagnosis:
  • 6
  • YEARS
    (range:<1 to 23 years)6
  • Undiagnosed and unmanaged, MMN will progress as patients:
    • Experience spreading muscle weakness, making it more difficult to identify asymmetry3
    • Lose muscle mass due to atrophy3
  • MMN cannot be cured, and disease progression depends on how long patients remain undiagnosed.1,2
  • Axon loss is the most important determinant of permanent weakness and disability2
Prognosis is better with early diagnosis1,2

References:

  1. Katirji B, Koontz D. Disorders of peripheral nerves. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley's Neurology in Clinical Practice. Vol 2. 6th ed. Philadelphia, PA: Saunders Elsevier; 2012:1915-2015.
  2. Vlam L, van der Pol W-L, Cats EA, et al. Multifocal motor neuropathy: diagnosis, pathogenesis and treatment strategies. Nat Rev Neurol. 2012;8(1):48-58.
  3. Shy ME. Peripheral neuropathies. In: Goldman L, Schafer AI, eds.Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:2396-2409.
  4. Bastos AF, Orsini M, Machado D, et al. Amyotrophic lateral sclerosis: one or multiple causes? Neurol Int. 2011:3(1);12-16.
  5. Olney RK, Lewis RA, Putnam TD, Campellone JV Jr. Consensus criteria for the diagnosis of multifocal motor neuropathy. Muscle Nerve. 2003;27(1):117-121.
  6. Slee M, Selvan A, Donaghy M. Multifocal motor neuropathy: the diagnostic spectrum and response to treatment. Neurology. 2007;69(17):1680-1687.
  7. Data on file, Baxter Healthcare Corporation. 2011.
  8. Van der Pol W-L, Cats EA, van den Berg LH. Intravenous immunoglobulin treatment in multifocal motor neuropathy.J Clin Immunol. 2010;30(suppl 1):S79-S83
  9. Van Schaik IN, L├ęger J-M, Nobile_Orazio E, et al. Multifocal motor neuropathy. In: Gilhus NE, Barnes MP, Brainin M, eds. European Handbook of Neurological Management: Volume 1. 2nd ed. West Sussex, England: Blackwell Publishing Ltd; 2011:343-350
  10. Van Asseldonk JTH, Van den Berg LH, Kalmijn S, et al. Axon loss is an important determinant of weakness in multifocal motor neuropathy. J Neurol Neurosurg Psychiatry. 2006;77(6):743-747
The largest
controlled clinical
trail in Multifocal
Motor Neuropathy
to date7
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