Canadian freestyle skier Sarah Burke remained in critical condition Thursday after a successful operation to repair a tear to an artery that caused bleeding in her brain.

Doctors put her into a coma to decrease swelling and pressure on her brain after her accident Tuesday, and she had surgery the next day.

"Sarah remains in critical condition in the Neuro Critical Care Unit," said neurointensivist Safdar Ansari, M.D, who is overseeing the team monitoring Burke. "With traumatic brain injury, our care is focused on addressing the primary injury and preventing secondary brain damage; as well as managing other injuries sustained at the time of the accident — all of which requires close monitoring and intensive care. At this moment, Sarah needs more time before any prognosis can be determined."  

Burke, a four-time Winter X Games champion in halfpipe skiing and one of the leading pioneers of her sport, injured herself while practicing on the halfpipe in Park City.

She tore a vertebral artery, which is located in the neck and supplies blood to the brainstem and the back part of the brain. Those parts control many critical functions, including balance and vision.

Tears can cause bleeding that disrupts blood flow to the brain, which in serious cases can lead to brain damage or death, said Dr. Andrew Naidech, medical director of the neuro-spine intensive care unit at Northwestern Memorial Hospital in Chicago.

He said those tears can be caused by severe twisting motions or impact causing sudden up-and-down movement of the head. Outcomes depend on how badly the damage interrupted blood flow to the brain or caused extensive bleeding.

Peter Judge, CEO of the Canadian freestyle team, said those who were near the superpipe when Burke fell told him it didn't look like a major accident at the time.

 A press conference is scheduled for Monday at the University of Utah Clinical Neurosciences Center.

Burke tried many of the toughest tricks in her sport and was the first woman to land a 1080 — three full revolutions — in competition. It was not known what move she was performing when the accident happened.