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.
(..) Che cazzo e ? Come on, let's get the hell out of here ! Come on, hurry up ! Why have the engines stopped ? l felt a shudder. l shouldn't worry, madam. We've likely thrown a propeller blade. - May l bring you anything ? - No, thank you. - Did you see anything ? (..)1997 Titanic