CINCINNATI - Otto Warmbier, who was medically evacuated from a 17-month detention in North Korea this week, has extensive loss of brain tissue and is in a state of unresponsive wakefulness, University of Cincinnati doctors said Thursday afternoon.   

Doctors said they don’t know what caused the brain damage. When asked whether it could be the result of beating or other violence while in prison, they said that Warmbier did not show any obvious indications of trauma, nor evidence of either acute or healing fractures.  

The doctors said they are not aware of anything from his previous medical history, prior to his time in North Korea, that might cause cardiopulmonary arrest. One of the more common causes of cardiopulmonary arrest is respiratory arrest, said Jordan Bonomo, neurointensivistand emergency medicine physician at UC Health. That cessation of breathing could be triggered by several things, including intoxication or a traumatic injury.