I had some surgery on my right bicep near the origin a year ago. They nicked a nerve on my forearm that controlls all the feeling on the skin on the inside of my forearm down to my wrist. While I didn't do any IGF after the surgery (didn't know about it), I have been for a few months now. There has not been any difference in the numbness I have in my arm.
In other words, it hasn't grown any nerves in my arm. Maybe if I'd used it right away?