Multifocal motor neuropathy

Title

Other Names:

MMN; MMNCB; Multifocal motor neuropathy with conduction block

Categories:

Nervous System Diseases

Summary Summary

Multifocal motor neuropathy (MMN) causes damage to the nerves in the arms and legs. Nerve damage begins in adulthood and slowly gets worse over time. One side of the body may be more affected than the other. Symptoms of MMN may include weakness in the hands and lower arms; cramping; involuntary contractions or twitching; wrist drop or foot drop, and wasting of the affected muscles. MMN is thought to be due to an abnormal immune response, but the underlying cause is not clear. Diagnosis is based on the symptoms, clinical exam, and specific laboratory testing. Guidelines for diagnosis have been published. Treatment includes intravenous immune globulin (IVIG). Most people with MMN have rapid improvement in weakness with IVIG, but this treatment needs to be repeated regularly. Cyclophosphamide has also been effective in treating MMN. Physical and occupational therapy may be helpful for some people with MMN.^[1]^[2]^[3]^[4]

Last updated: 3/15/2021

Symptoms Symptoms

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.^[5]^[6] 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.^[5]^[7]

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

Showing of 12 |

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Last updated: 2/1/2021

Cause Cause

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]^[8]

Last updated: 3/7/2016

Inheritance Inheritance

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

Diagnosis Diagnosis

Multifocal motor neuropathy is diagnosed based on the symptoms, clinical examination, and specialized laboratory testing. Standards for diagnosing multifocal motor neuropathy have been published in the medical literature.^[2]

Last updated: 3/15/2021

Treatment Treatment

Multifocal motor neuropathy (MMN) is considered treatable with intravenous immune globulin (IVIG). Early treatment shortly after symptoms begin is recommended.^[8] 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

Statistics Statistics

It has been estimated that less than 1 per 100,000 people in the world have multifocal motor neuropathy (MMN). The number of people with MMN is different in different countries. Men are more likely to have MMN than women.^[4]

Last updated: 3/15/2021

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Research Research

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.

Organizations Organizations

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

GBS/CIDP Foundation International
375 East Elm Street, Suite 101
Conshohocken, PA 19428
Toll-free: 1-866-224-3301 (from North America)
Telephone: +1-610-667-0131
Fax: +1-610-667-7036
E-mail: info@gbs-cidp.org
Website: https://www.gbs-cidp.org/
Neuropathy Action Foundation
1950 Old Tustin Avenue
Santa Ana, CA 92705
Toll-free: (877) 512-7262
E-mail: info@NeuropathyAction.org
Website: http://www.neuropathyaction.org/
The Foundation for Peripheral Neuropathy
485 Half Day Road
Suite 350
Buffalo Grove, IL 60089
Telephone: +1-877-883-9942
Fax: +1-847-883-9960
E-mail: https://www.foundationforpn.org/contact-us/
Website: https://www.foundationforpn.org

Social Networking Websites

Visit the following Facebook groups related to Multifocal motor neuropathy:
MMN - Multifocal Motor Neuropathy

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Learn More Learn More

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.

GARD Answers GARD Answers

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

Have a question? Contact a GARD Information Specialist.

References References

Lange D and Robinson-Papp J. Multifocal motor neuropathy. UpToDate. Waltham, MA: UpToDate; 2016; http://www.uptodate.com/contents/multifocal-motor-neuropathy.
Joint Task Force of he EFNS and the PNS.. European Federation f Neurological Societies/Peripheral Nerve Society guideline on management of multifocal motor neuropathy. Report of a joint task force of the European Federation of Neurological Societies and the Peripheral Nerve Society--first revision. J Peripher Nerv Syst.. Dec 2010; 15(4):295-301. https://pubmed.ncbi.nlm.nih.gov/21199100/.
Yeh WZ, Dyck PJ, van den Berg LH, Kiernan MC, Taylor BV. Multifocal motor neuropathy: controversies and priorities. J Neurol Neurosurg Psychiatry.. Feb 2020; 91(2):140-148. https://pubmed.ncbi.nlm.nih.gov/31511307/.
Hameed S, Cascella M.. Multifocal Motor Neuropathy.. StatPearls. Updated Feb 7, 2021; https://pubmed.ncbi.nlm.nih.gov/32119411/.
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.
Zivkovic S. Multifocal Motor Neuropathy With Conduction Blocks. Medscape Reference. September 27, 2016; https://emedicine.medscape.com/article/1174021-overview.
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.
MMN Overview. GBS/CIDP Foundation International. 2016; http://www.gbs-cidp.org/variants/mmn-overview/.