The answer lies with your vet. You have two forms of this disease either wet or dry. Depending on how advanced the disease is, will depend on the outcome for it. I am sorry to be so blunt, but knowing the right questions to ask your vet might be helpful for you to getting the answers. There is no known cure yet, but the disease does go in stages and it as I said, it will determine how advanced the stages are. The fact that there is neurological damage as well just makes the decision all that more painful to be reached. The hardest part about this situation is knowing when to do the right thing without causing more suffering to the animal. Again, let your vet guide you, lean on his expertise and knowledge and also talk to your cat and let the cat know what is going on and how you feel. Believe it or not, it helps not only you but the cat too.