Motor neurone disease is what the scientist Stephen Hawking has, if you have ever seen him on TV. I saw him recently on a programme explaining how the Universe gradually came to be after the Big Bang. He’s in an electronic wheelchair and speaks with an electronic voice.
If you look at him, you can see what the symptoms are! I believe it’s basically when the neurones in your body that allow you to move it and control it gradually die. This means that you gradually lose your ability to move your body, as he has. Eventually you have to use a wheelchair; when you lose the ability to control your vocal apparatus as well, you have to speak as he does, using an electronic voice that is controlled by whatever muscles you do still have control of. I don’t think there is any cure, so, unfortunately, MND always kills you eventually.
If you Google
motor neurone disease
you’ll find quite a few pages about it. There’s a Wikipedia page, of course, and there’s also a page explaining the disease written by the MND Association – that page looks a bit more user-friendly than the Wikipedia one!