I think the patient would spend the rest of their life in physical rehabilitation. They would have to train their brain to remap every muscle movement. Coordination would be a nightmare and a major fall risk (very common way to die in a hospital). Then there is the whole digestive system, it is hard to believe it runs completely independently, and if that isn’t working right, it would be a horrible death.

As fascinating as these ideas are, hopefully repairing a severed spinal cord will be a reality soon: https://news.yale.edu/2021/02/22/yale-scientists-repair-inju...