The 29-year-old was airlifted from Park City, Utah, to Salt Lake City after an accident during training on a halfpipe Tuesday.
Burke was placed into an induced coma to relieve stress on her brain and underwent surgery Wednesday afternoon.
"With injuries of this type, we need to observe the course of her brain function before making definitive pronouncements about Sarah's prognosis for recovery," Dr. William T. Couldwell, professor and chair of neurosurgery at the University of Utah, said in a statement Thursday. "Our neuro critical care team will be monitoring her condition and response continuously over the coming hours and days."
Burke tore a vertebral artery, which are located in the neck and supply blood to the brainstem — the back part of the brain which controls consciousness.
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.
Burke, a native of Barrie, Ont., who grew up in nearby Midland before moving to Squamish, B.C., was training with a private group at the time of the accident.
A four-time Winter X Games champion, Burke is considered a halfpipe pioneer who also lobbied tirelessly to get her sport included in the Winter Olympics. Halfpipe skiing will debut at the 2014 Games in Sochi, Russia.
Burke's husband, Rory Bushfield, and other members of her family are with the skier in hospital.
"Sarah is a very strong young woman and she will most certainly fight to recover," Bushfield said in a statement Wednesday.
The accident happened in the early afternoon on the same halfpipe where snowboarder Kevin Pearce was critically injured during training Dec. 31, 2009. Pearce suffered traumatic brain injuries but has since recovered and returned to riding on snow last month.
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.
— With files from the Associated Press
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