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Start free with EleplanMultifocal motor neuropathy
ORPHA:641Disease
Also called MMN · MMNCB · Multifocal motor neuropathy with conduction block
What it is
Multifocal motor neuropathy (MMN) is a rare acquired immune-mediatedneuropathy characterized clinically by a purely motor deficit with conduction block and asymmetric multifocal weakness, fasciculations, and cramping.
Key facts
- Prevalence
- 1-9 / 100 000
- Age of onset
- Adult
- Inheritance
- Unknown
- Classified as
- Disease
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Common30–79%
11- Abnormality of ganglioside metabolism
- FasciculationsDiagnostic criterion
- Functional motor deficit
- Increased CSF protein concentration
- Limb muscle weaknessDiagnostic criterion
- Limited wrist extension
- Motor conduction block
- Muscle spasmDiagnostic criterion
- Progressive muscle weakness
- Reduced tendon reflexesDiagnostic criterion
- Weakness of long finger extensor muscles
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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