"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," Couldwell said. "Our neuro-critical care team will be monitoring her condition and response continuously over the coming hours and days."
Indeed, Burke is likely to spend several more days in an induced coma while doctors wait for swelling in the brain to subside, said Anders Cohen, the chief of neurosurgery and spine surgery at The Brooklyn Hospital in New York. At that point, doctors will be able to better assess her prognosis, he said. Serious cases such as Burke's can result in brain damage or even death.
Cohen is not involved in Burke's treatment, but explained elements of what is likely happening in the hospital.
He said doctors have two main concerns when treating an injury such as the one Burke suffered. One is the amount of damage that might have been done due to the bleeding into the brain. The other is whether the parts of the brain normally supplied by the vertebral artery received enough blood before the artery could be repaired.
"Those are two front-and-center concerns, from a doctor's standpoint," Cohen said.
Cohen said Burke probably had her head and neck bent hard to one side when she fell, causing the tear in the artery, which supplies blood to the brainstem in the back part of the brain that controls consciousness.
The 29-year-old Burke is widely considered the foremost pioneer in her main sport of halfpipe skiing similar to snowboarding's halfpipe, except on skis and she lobbied aggressively to have it included in the Olympics, where it will debut at the 2014 Sochi Games in Russia.
She is a four-time Winter X Games champion and had been scheduled to defend her 2011 title later this month in Aspen, Colo.
Before the accident, Burke was on a path that would have made her an odds-on favorite to win more X Games gold and possibly even the gold medal at in Sochi. But even though doctors can monitor certain body reflexes while Burke is comatose in order to assess her condition, Cohen said it will be awhile before they know everything. "For the big picture, that's going to be at best days away."