Diagnosing and Treating Multifocal Motor Neuropathy (MMN)

What is MMN?

MMN is a rare immune-mediated motor neuropathy, which presents as slowly progressive, asymmetric, and predominantly distal limb weakness.^1,2

Weakness typically begins in the fingers or thumb and may include involuntary fasciculations and cramping. As the disease advances, patients may experience wrist drop, foot drop, and/or loss of grip strength, and weakness may move proximally.^2-4

MMN has a prevalence of
1-2 in 100,000²

MMN affects nearly 3x
more men than women¹

Mean age onset of 40 years
(range 20-70 years)¹

Diagnosis is often delayed

MMN presents with symptoms similar to those of other neuropathies, such as amyotrophic lateral sclerosis (ALS). As a result, misdiagnosis does occur and contributes to delays in diagnosis.¹

Unfortunately, for many patients it can take a considerable amount of time from symptom onset to receiving a diagnosis. The mean time to diagnosis is 6 years (range: <1-23 years).⁴* If left undiagnosed and unmanaged, MMN continues to progress.^1,3

Undiagnosed and unmanaged, MMN continues to progress^1,3

AMEND the time to diagnosis

When considering MMN, AMEND—an acronym created by TAKEDA—can help you recognize some of the hallmark symptoms.^†

Asymmetric
Distribution of weakness is asymmetric^2-4
Motor without sensory
Motor impairment (muscle weakness) without objective sensory impairment³
Elevated anti-GM1 antibody titers
Present in around 50% of patients⁵
Nerve conduction block
Typically present, but may be activity dependent and difficult to detect. May be easier to detect in advanced disease^1,2,6
Distal
Most common clinical presentation of weakness typically affects the distal arm/leg muscles^2-4

^†In addition to the above, muscle mass is preserved despite profound weakness in early disease but may be decreased due to atrophy in advanced disease. Axonal damage and loss are correlated with muscle weakness and may be less pronounced in early stages.