The benefits of the cold have beeb outlined previously by the poster above.
Additionally, it depends on the necessity and success of the CPR: the whole point of doing CPR is to provide oxygen to the brain.
Finally, brain is known for such feature as plasticity. Meaning that different brain networks, that is connections between brain cells, are continiously created and lost. This is in part why training a sport makes you good at it, why you forget a language you no longer use, why depression creates a downwards spiral and why in the weeks after their stroke, patients have to exercise, not lie in bed and rest. So in the case of brain injuries, people can re-learn previously held skills that they have lost, reforming new connections and networks - by trying and practicing. By far the biggest chunk of recovery takes part spontaneously during the first 24-48 hours, as the oxygen via blood flow is restored. Next cut-offs could be around the one-month mark, three-month mark and finally at the one year mark, as any functions that you have not regained within a year are statistically unlikely to be recovered (have a peek at
graph1 and
graph2). In the case of children, their brains are still developing and cells still growing, so for many reasons, their brain plasticity is even greater and function regaining even better.
And of course, what your brain damage does to you is obviously directly influenced by where it's at. If you get a stroke in your cerebellum, at the back of the head, you might get some balance problems and some emotional problems, but your speech might not get affected at all. Whereas if you get your stroke in the frontal lobe, your whole personality can change.