January 17, 2017 E-Pearl of the Week: Multifocal motor neuropathy

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January 3, 2017

Multifocal motor neuropathy 

Multifocal motor neuropathy (MMN) is a purely motor demyelinating neuropathy that presents with asymmetric weakness due to the involvement of individual peripheral nerves. It is sometimes confused with ALS especially when conduction block is present. CSF studies show normal protein, in contrast to other demyelinating polyneuropathies. MMN is usually associated with anti-GM1 antibodies, but the presence of these antibodies is not required for the diagnosis. MMN responds well to intravenous immunoglobulins, but steroids and plasmapheresis are ineffective and sometimes worsen symptoms. There are case series and non-randomized clinical trials suggesting variable benefits of other agents such as mycophenolate mofetil, cyclophosphamide, cyclosporine, azathioprine, interferon beta-1a and rituximab.


  1. Jinka M, Chaudhry V. Treatment of Multifocal Motor Neuropathy. Curr Treat Options Neurol 2014; 16: 269.
  2. Nobile-Orazio E, Gallia F. Multifocal motor neuropathy: current therapies and novel strategies. Drugs 2013; 73: 397-406.
  3. Carpo M, Cappellari A, Mora G, et al. Deterioration of multifocal motor neuropathy after plasma exchange. Neurology 1998; 50: 1480-1482.

Ronnyson Susano Grativvol, MD, Resident Physician - Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC-FMUSP).

Dr. Grativvol reports no disclosures.

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