seize up phrasal verb (see also seize)
a) if an engine or part of a machine seizes up, its moving parts stop working and can no longer move, for example because of lack of oil:
The mechanism had seized up.
b) if a part of your body, such as your back, seizes up, you suddenly cannot move it and it is very painful

[TahlilGaran] Dictionary of Contemporary English ▲

seize up
to suddenly stop moving or working.
I hit two keys at the same time and my computer just seized up.

Her leg seized up and she had to be carried out.

[TahlilGaran] English Idioms Dictionary ▲