I just experienced a feeling like an electrical surge in my shoulder (left) that lasted for several seconds and caused my arm to flail a bit and be somewhat uncontrollable -- I could get it to my computer keyboard, but did not have sufficient control to put my hand over the keys I wanted it to go to or to stop it from flailing off the keyboard. The electrical sensation went as far as my elbow, but no further, I think, and did not move into my neck or torso. Everything is working just fine now, as far as I can tell. It seemed to be centered where I had a bursitis problem a few months back.