Ulma Nerve?

I had open re-constructive shoulder surgery (Bankhart repair) in 1998. I started experiencing numbess in my hand after the surgery. I had my second re-constructive shoulder surgery by scope in 2008 and continue to have numbess and tingling in my 4-5 fingers. I am possibly lookin at a 3rd re-constructive shoulder surgery now. I had a NCV and an EMG performed yesterday. While they were conducting the EMG specifically at the Ulma nerve they started hearing something like a heartbeat or a drum beat which got all of their attention. They would not tell me anything other than does my neck hurt and I will need more test. Can anyone tell me what this means and could my Shoulder surgeries have caused this?