I 'shudder' at the thought of what might happen. = 'I shudder to think' (of) what might happen. [=I am very worried/fearful about what might happen]
He 'shuddered' [='quivered, trembled'] 'with' fear when he heard the scream.
I felt a 'shudder' [='tremble'] in the floor as the truck drove by.
(..) She's fresh. You've gone out of your mind. One can't deny that she is unusual. Who is she? Don't even ask. The thought of her makes me shudder. Dreadful girl. If this is some sort ofjoke... It's no joke. If we do her over and fix her up, she'd be great. She'd devour us all. - Come on, Maggie. (..)1957 Funny Face