GRENOBLE, France — Doctors treating Michael Schumacher refused Monday to predict the outcome for the former Formula One driver, saying they were taking his very critical head injury “hour by hour” following a skiing accident.

Chief anesthesiologist Jean-Francois Payen told reporters the seven-time racing champion is still in a medically induced coma. He said the medical team was focusing only on his current condition.

“We cannot predict the future for Michael Schumacher,” Payen said.

“He is in a critical state in terms of cerebral resuscitation,” he added. “We are working hour by hour.”

Schumacher, the most successful driver in Formula One history, arrived at the Grenoble University Hospital Center a day earlier already in a coma and immediately underwent brain surgery.

The German driver was skiing with his son Sunday morning in the French Alpine resort of Meribel when he fell and hit the right side of his head on a rock. He was wearing a helmet, but the doctors said it was clearly not sufficient to prevent a serious brain injury.

“Someone who had suffered this accident without a helmet would not have made it this far,” Payen said.

Schumacher will turn 45 on Friday.