National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Multifocal motor neuropathy


Other Names:
MMN; MMNCB; Multifocal motor neuropathy with conduction block
Categories:
Multifocal motor neuropathy (MMN) is a rare neuropathy characterized by progressive, asymmetric muscle weakness and atrophy (wasting).[1] Signs and symptoms may include weakness in the hands and lower arms; cramping; involuntary contractions or twitching; wrist drop or foot drop, and atrophy of affected muscles.[2][3] MMN is thought to be due to an abnormal immune response, but the underlying cause is not clear.[1] Most people treated with intravenous immune globulin (IVIG) have rapid improvement in weakness, but maintenance IVIG is usually required for sustained improvement.[1] Cyclophosphamide has also been effective in treating MMN. Physical and occupational therapy may be helpful for some people with MMN.[3]
Last updated: 5/14/2018
Signs and symptoms of multifocal motor neuropathy (MMN) may include weakness; cramping; involuntary contractions or twitching; wrist drop or foot drop; and wasting (atrophy) of affected muscles.[2][3] Atrophy occurs late in the course of the condition.[1] Muscles of the hands and lower arms are most commonly affected, but muscles of the lower limbs may also be involved. The symptoms are often asymmetrical, meaning that they differ on the right and left side of the body.[2][4]
Last updated: 5/14/2018

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Progressive distal muscle weakness 0009063
30%-79% of people have these symptoms
Fasciculations
Muscle twitch
0002380
Functional motor deficit 0004302
Ganglioside accumulation 0004345
Increased CSF protein 0002922
Limb muscle weakness
Limb weakness
0003690
Limited wrist extension 0006251
Motor conduction block 0012078
Muscle spasm 0003394
Progressive muscle weakness 0003323
Reduced tendon reflexes 0001315
Weakness of long finger extensor muscles 0009077
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Last updated: 7/1/2020
The exact underlying cause of multifocal motor neuropathy (MMN) is poorly understood. It is considered an immune-mediated disorder (due to an abnormal immune system response), both because IVIG therapy improves symptoms, and many patients have anti-GM1 antibodies. Research to further understand the cause of MMN is underway.[1][5]
Last updated: 3/7/2016
We are not aware of any evidence that multifocal motor neuropathy (MMN) is inherited or of any reports of familial cases (occurring in more than one person in a family). Furthermore, to our knowledge, no specific genes known to be associated with MMN have been identified.
Last updated: 3/7/2016
Multifocal motor neuropathy (MMN) is considered treatable with intravenous immune globulin (IVIG). Early treatment shortly after symptoms begin is recommended.[5] Most people have a fairly rapid improvement in weakness with IVIG, but the improvement generally does not last beyond a few months. Maintenance IVIG infusions are usually needed every two to six weeks. For those with severe disease whose symptoms don't respond to IVIG (or for those who become resistant), treatment options are limited. Several reports have suggested that cyclophosphamide may be partially effective.[1]
Last updated: 3/7/2016

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Multifocal motor neuropathy. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Social Networking Websites

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The GBS/CIDP Foundation International provides information about this condition. The GBS|CIDP Foundation International is a global non-profit organization supporting individuals and families affected by Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy (CIDP), and related syndromes through a commitment to support, education, research, and advocacy.
  • The National Institute of Neurological Disorders and Stroke (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
  • The Neuropathy Action Foundation (NAF) provides an online information about Multifocal motor neuropathy. The NAF is dedicated to ensuring neuropathy patients obtain resources, information and tools to access individualized treatment to improve their quality of life.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Multifocal motor neuropathy. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • Is multifocal motor neuropathy hereditary? We have no family history that I know of. My son was diagnosed with MMN at age 29, if he has children are they at risk? See answer


  1. Lange D and Robinson-Papp J. Multifocal motor neuropathy. UpToDate. Waltham, MA: UpToDate; 2016; http://www.uptodate.com/contents/multifocal-motor-neuropathy.
  2. NINDS Multifocal Motor Neuropathy Information Page. National Institute of Neurological Disorders and Stroke. 2016; https://www.ninds.nih.gov/Disorders/All-Disorders/Multifocal-Motor-Neuropathy-Information-Page.
  3. Zivkovic S. Multifocal Motor Neuropathy With Conduction Blocks. Medscape Reference. September 27, 2016; https://emedicine.medscape.com/article/1174021-overview.
  4. Guimarães-Costa R, Bombelli F, and Léger JM. Multifocal motor neuropathy. Presse Med. June 2013; 42(6 Pt 2):e217-24. https://www.ncbi.nlm.nih.gov/pubmed/23623583.
  5. MMN Overview. GBS/CIDP Foundation International. 2016; http://www.gbs-cidp.org/variants/mmn-overview/.