Amyotrophic lateral sclerosis, known as ALS in most of the world, and "Lou Gehrig's disease" in the United States, (after a famous baseball player who died of it), is a motor neuron disease that slowly kills off the part of your brain that tells your body how to move. The result being that a person suffering from it slowly becomes more and more paralyzed until they can't breathe anymore, at which point they die. The rest of the brain is unaffected. A similar condition is Locked-in Syndrome, in which a person abruptly becomes paralyzed, usually after a stroke. (In which case the motor-control cortex of the brain probably died in the stroke.)
Motor-cortex conditions are rather baffling to treat. The muscles are technically fine, but the person can't move them. The muscles then deteriorate from a lack of moving. The problem lies in the brain, which we know the least about and are the most afraid of messing around with, lest we make it worse.
I think, in the circumstances, I would want to try to invent a cybernetic motor-cortex replacement. This would take 100 years of neurology research, and the best electronic-communication experts known to man. And having done so, no one would ever be paralyzed for brain-reasons again. If this research also found a good way to reconnect severed nerves, then all paralysis would thereafter be treatable.