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- Diff Dx:
    - Amyotrophic Lateral Sclerosis;
    - Poliomyelitis;
    - Spinal Muscular Atrophy;
         - EMG will reveal a neuropathic disorder, w/ muscle denervation;
         - nerve-conduction velocities are normal;

- EMG: Diff Dx:
    - typically, an EMG of patient w/ myopathic disease shows a decreased amplitude and duration of response;
    - in contrast, an EMG of a patient w/ a neuropathic disorder shows an increased amplitude & duration of response;
    - demyelinating peripheral neuropathies show slowed nerve-conduction velocity;
    - nerve-conduction velocities are normal in patients who have SMA;

- Fasiculation Potentials:
    - fasciculation potentials are caused by the spontaneous discharges of group of muscle fibers representing a whole or part of motor unit, 
          usually producing a visible twitching in the muscle;
    - fasciculation potentials most often occur in disease of anterior horn cells;
    - commonly occur in:
          - ALS;
          - progressive spinal muscular atrophy;
          - polio;
          - syringomyelia