Mutilated: (Verb)
Definition: to injure, disfigure, or make imperfect by removing or irreparably damaging parts
Dictionary.com
They stumbled blindly through their lives: creatures so abused and mutilated in body, so dimmed and confused by pain, that they considered themselves unworthy even of hope.
This just means that these creatures were so abused and injured, and the body was confused with pain.
