Multifocal Motor Neuropathy (MMN)

What is multifocal motor neuropathy?

Multifocal motor neuropathy (MMN) is a rare disorder that is characterized by progressive muscle weakness. Multifocal means coming from two or more areas, motor refers to the motor nerves, and neuropathy is the disease or dysfunction of the peripheral nerves. 

What are the symptoms of multifocal motor neuropathy?

MMN is a progressive disorder, so the symptoms worsen slowly over time. The major symptom is muscle weakness in the arms and legs. This makes it difficult for affected individuals to perform fine motor skills, such as using keys to unlock doors. Foot drop and trouble walking are also associated with this muscle weakness. As the disease progresses, severe fatigue and functional disability. Other symptoms include:

• Cramping
• Twitching
• Muscle atrophy
• Decreased muscle tone
• Absent deep tendon reflexes

What causes multifocal motor neuropathy?

The exact cause of this condition is not completely understood, but medical professionals are aware that it is related to the immune system. They believe that a conduction block damages the motor nerves. In addition, autoantibodies attack GM 1 ganglioside, but medical professionals do not know if this is a cause or by-product of MMN. 

How is multifocal motor neuropathy diagnosed?

Doctors will look for the characteristic symptoms, review a patient’s history, and perform a clinical evaluation. Tests will be used to diagnose MMN as well, such as nerve conduction studies, electromyography, and other laboratory tests. 

What are the treatments for multifocal motor neuropathy?

A team of specialists is often required to best treat MMN. Physical therapy is a major part of treatment, and Gammagard Liquid 10% has been approved by the FDA as well. If these methods do not work, doctors will move to try other medications. 

Where can I find out more about multifocal motor neuropathy?

• • NORD
  • NIH
  • GBS/CIDP Foundation