I have experienced this at different times in my training. Although I never found the root of the problem, I can offer suggestions that helped me.
First, as stated earlier, don't grip the bar with a death grip and make sure your wrist is straight. Make sure the bar is not too far out (fingers) or in (palm).
Try to throw in some exercises using the narrower grip on the EZ bar.
After finishing your set, rest the bar on supports. SLOWLY release your grip one finger at a time, starting with your pinky. This completely eliminated the sharp radiating pains for me.
Maybe someone can get in here with more technical details as to WHY this is happening. But these things have worked well for me in the past.