In a book I am working on the main character falls off of a one-story wall injuring his back. Could he be paralyzed? If so, would it be possible for paralysis to set in an hour or two later? Would he be able to remain conscious and still walk for about an hour? He is a spy, mid 20’s, strong, and loves to run.
In my experience, I’ve never seen a delay in onset of paralysis. Usually, it is immediate. I’ve not personally seen people with devastating paralysis from a fall from this height. Broken legs/arms, lacerations, and concussions . . . sure. Could a spinal cord injury happen? Of course there are always outliers. If you did write this, it would help believability if the character fell directly onto their head (called an axial loading injury) or onto another hard object (like a rock or something with a hard edge) to increase the chance of a complex fracture causing paralysis.
I did some hunting regarding spinal bones specifically. This article says three meters (which equates to about 10 feet or one story) can cause spinal fracture, but just because you break the bones doesn’t necessarily mean paralysis. A person with a stable fracture of their back can be up and walking around. I’ve seen this plenty of times.
I did find one article where a woman did have delayed onset of paralysis of four days, but if you read through the article she had a significant mechanism of injury and died as a result of complications of her injuries.
Best of luck with this story!