While Phineas was working, a 13 pound crowbar was shot through his head. His men who worked with him rushed him to the doctor.
Miraculously, Phineas survived. The blood loss and brain swelling should have killed him, but he came out fine. Physically, at least.
Once Phineas was released from the doctor's, he went back to work. Gage had changed; he was disrespectful, vulgar, and did not make good choices. He had become angry and irritating. The company let him go and he died eleven years later.