Motor neurone disease (MND): differential diagnosis

Peripheral differentials: multifocal motor neuropathy (MMN)

• MMN is the closest differential diagnosis of MND
• Imaging of the ulnar and median nerves may help to differentiate them
• The cross-sectional areas (CSA) of the nerves are larger in MMN
• High serum neurofilaments suggest MND rather than MMN

References

1. Traynor BJ, Codd MB, Corr B, et al. Amyotrophic lateral sclerosis mimic syndromes: a population based study. Arch Neurol 2000; 57:109-113.
2. Jongbloed BA, Haakma W, Goedee HS, et al. A comparative study of peripheral nerve MRI and ultrasound in MMN and ALS. Muscle Nerve 2016; doi: 10.1002/mus.25391 (Epub ahead of print).
3. Kleinveld VEA, Keritam O, Horlings CGC, et al. Multifocal motor neuropathy as a mimic of amyotrophic lateral sclerosis: Serum neurofilament light chain as a reliable diagnostic biomarker. Muscle Nerve 2024; 69:422-427.
4. Huijbers MG, Niks EH, Klooster R, et al. Myasthenia gravis with muscle specific kinase antibodies mimicking amyotrophic lateral sclerosis. Neuromuscul Disord 2016; 26:350-353.
5. Neutel D, Miltenberger-Miltenyi G, Silva I, de Carvalho M. Chorea-acanthocytosis presenting as motor neuron disease. Muscle Nerve 2012; 45:293-295.
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Related checklists

• Motor neurone disease (MND): neuromuscular features
• Motor neurone disease (MND): other features
• Motor neurone disease (MND): diagnostic criteria
• Motor neurone disease (MND): prognostic features