Multifocal motor neuropathy

Multifocal motor neuropathy is a rare, immune-mediated neuropathy characterized by progressive asymmetrical limb weakness without sensory deficits
Males are more affected than females (3:1) and the mean age of onset is 40

  • The most common presentation is wrist drop and impaired grip strength
  • Distal muscles are affected more commonly than proximal ones 
  • Upper limb is more commonly affected than lower limb 
  • There may be fasciculations 
  • There may be muscle wasting 
  • There is no sensory involvement 
  • There are no upper motor neuron signs

  • Nerve conduction studies – show multifocal partial conduction blocks in motor but not sensory nerve fibres 
  • High titre IgM anti-GM1 serum antibodies – 20-80% of patients 

  • IV IG improves symptoms and slows progression 
  • Plasma exchange/corticosteroids are not indicated and can make symptoms worse 

Differential diagnoses 

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Secret collector of interesting anonymised ECGs. Fan of the Bath Photomarathon. Lover of cream teas. [Sarah Hudson] (Your Picture)