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"We have won some time but we must continue an hour-by-hour surveillance...It is premature to speculate on his condition," he said, adding that it could still be qualified as "critical".
Emmanuel Gay, head of the hospital's neurosurgery service, said the operation carried out during the night involved removing a large hematoma - the medical term for a build-up of blood - from the left-hand side of Schumacher's brain.
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"It was larger and more accessible (than others) ... We judged we could remove it without taking any risks," Gay said.
He said the operation was designed to reduce, within Schumacher's skull, the pressure on the brain, which suffered injuries including lesions and contusions from Sunday's fall.
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The retired motor racing champion, 44, slammed his head on a rock while skiing off-piste on Sunday morning in the French Alpine resort of Meribel, where he has a vacation home.
Doctors said the fact that he was wearing a helmet had enabled him to make it to the hospital alive. Payen said the medical team in Grenoble had discussed the operation with Schumacher's family. He said the condition of the German motor racing great was still too fragile to consider transferring him to another hospital for the time being.