What is the role of medications in the treatment of multifocal motor neuropathy (MMN) with conduction block?

Updated: Nov 12, 2018
  • Author: Sasa Zivkovic, MD, PhD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Multifocal motor neuropathy (MMN) is an immune-mediated disorder, and while multiple immunomodulatory and immunosuppressive treatments have been used, only intravenous immunoglobulin (IVIG), [21, 22, 23] subcutaneous immunoglobulin (SCIG) [24, 25] and cyclophosphamide have been consistently effective. Delay of treatment may result in increased weakness and disability. Anecdotal reports also indicate that rituximab, [26, 27, 28] interferon-beta, azathioprine and cyclosporine may be efficacious. [29, 30]

The presence of conduction blocks or elevated titers of anti-GM1 antibodies are not reliable predictors of response to treatment with IVIG.

Most patients (~80-90%) improve with IVIG, but frequently long-term maintenance IVIG infusions are required to prevent worsening of symptoms. [23, 31] The pharmacokinetics of IVIG vary among individual patients and may influence the clinical response. [32] Subcutaneous immunoglobulin (SCIG) infusions may be used as an alternative to IVIG with similar efficacy and improved safety profile. [33]

Cyclophosphamide may be used in combination with plasmapheresis. Lack of benefit was reported for 1 patient who received high-dose cyclophosphamide treatment followed by autologous stem cell transplantation. [34]

Corticosteroids or plasmapheresis (without cyclophosphamide) is not effective, and in some cases, MMN may even worsen. Mycophenolate is ineffective as adjunct treatment with IVIG. [31]

Recent reports describe effective treatment with cyclosporine and rituximab in a small number of patients, but additional data are needed before these would be recommended for treatment of MMN.

Other treatments used with variable success include interferon-beta and azathioprine.

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