US student Otto Warmbier suffered extensive brain damage while detained in North Korea

An American college student who emerged from prison in North Korea in a coma has severe brain damage, but doctors don't know what caused it, a medical team treating him in Ohio has said.The doctors described Otto Warmbier as being in a state of “unresponsive wakefulness” but declined to discuss his outlook for improvement, saying such information would be kept confidential.At an earlier press conference, Otto's father said does not believe the North Korea’s claims about his son