A good friend's mother was just diagnosed with a slow moving ALS (aka Lou Gehrig's disease.)
http://www.alsa.org/ At this point, they are still figuring out living options, since the only treatment is one that slows the disease, nothing cures or reverses it.
Possible upside, she could live a relatively good life for the next five or more years.
Worst outcome, the disease picks up speed and she dies in a couple of years.
Guaranteed - she will slowly lose movement until she is paralyzed. The destruction of neurons will eventually stop her ability to swallow and breathe.
My friend's dad died when he was an undergrad, and his brother lives across the country. The only other near relatives are also elderly.
ALS is a nasty one, no doubt about it.