If you're paralyzed, you can describe your condition as palsy. Your grandfather's palsy might confine him to a wheelchair.
The noun palsy can be used to talk about an inability to move, or alternately, an uncontrollable shaking that's caused by some condition or disease. Some kinds of palsy affect one side of a person's face, leaving half of it paralyzed. The Greek origin of palsy is paralysis, which literally means "loosen," from the word paralyein, and its roots para, "beside," and lyein, "loosen or untie."