Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Multifocal motor neuropathy ?
    ### Response:
    Multifocal motor neuropathy (MMN) is a rare neuropathy characterized by progressive, asymmetric muscle weakness and atrophy (wasting). Signs and symptoms include weakness in the hands and lower arms; cramping; involuntary contractions or twitching; and atrophy of affected muscles.
    