Multifocal motor neuropathy with conduction blocks (MMNCB) Home A-Z Health Information Health Library A-Z Multifocal Motor Neuropathy With Conduction Blocks (MMNCB) Overview MMNCB is an autoimmune neuropathy affecting middle-aged males causing weakness in a specific nerve distribution. It results in sequential weakness of different parts of limbs. Causes It is caused due to generation of autoantibodies (anti GM1), which damage the nerve fibres and leads to failure of conduction of nerve impulse. Risk factors It is a rare disorder and the risk factors are not known. Symptoms Weakness and atrophy of hands and legs, hand grip weakness, wrist and foot dropDistal involvementNo sensory symptoms Specialist to approach Neurologist Diagnosis Clinical signs and symptomsNCV: demonstration of conduction block (>50% decrease in amplitude of motor unit across proximal and distal stimulation)Nerve biopsy (rarely needed)Blood tests for anti GM1 antibodies Treatment Immunomodulation using intravenous immunoglobulins. Other immunomodulators such as cyclophosphamide, or rituximab may also be usedRehabilitation using orthosis and assistive devices