I agree with Bogertophis I think you just hydrate and hope for the best.
I think they have to think about quality of life here, is this neuro issue bad enough that it's going to severely impact it's quality of life? Hard to tell without some observation. I think they should be prepared and prepare the child for worst case. Unfortunately, animals are typically a child's first introduction to the concept of life and death, so I'm sure that's hard.
Just based on your explanation of the situation, I'd say recovery may be unlikely. I'm no vet obviously, but if the vet offered to euthanize immediately, I would say their opinion on recovery is probably the same.