For more about twitching look up fasciculation
Specifically, a fasciculation or “[I]muscle twitch[/I]”, is a small, (and, in my case repeating) local, involuntary muscle contraction followed by relaxation visible under the skin probably caused by the spontaneous discharge of a bundle of skeletal muscle fibers (muscle fascicle) as they degenerate, regenerate or whatever it is they are doing.
Fasciculations have a variety of causes, but the one that concerns us is due to disease of the motor neurons.
A fasciculation usually will not cause an entire limb or digit (finger or toe) to move.
Generally speaking, when I feel better (CIDP) I do not fasciculate!