What would happen if someone gave Voldemort brain damage?

Let's say he still has his horcruxes intact, someone walks up behind him while he's monologuing and hits him in the head with a sock full of marbles. Voldemorts skull caves in and he becomes a vegetable. Obviously the death eaters could easily kill the dude with the sock but would Voldemort be a threat anymore? If he was just confined to a wheelchair and couldn't do anything? I mean at that point couldn't they just put him in a holding cell and feed and water him to make sure he doesn't die, and then he's no longer a problem? Horcrux hunt could commence while not having the threat of Voldemort there. I don't think the death eaters would still follow him.