Michael Schumacher "would have died" from the impact of his skiing accident if he was not wearing a helmet.
A spokesman for the hospital said: "Michael Schumacher was the victim of very serious trauma. He was very agitated when he arrived and we decided he was in a critical situation and he quickly went into a coma.
"The neurosurgical treatment he received brought us quite a lot of information. We had to operate urgently to release some pressure in his head. Unfortunately, he has some lesions within his brain."
Professor Jean-Francois Payen added:
"I'd say this accident happened in the right place because he was taken into hospital immediately and operated on as soon as he arrived, this meant his state is critical and he is still in a coma and he will be kept in a coma.
"Everything that needed to be done has been done at the moment we can't really say when he will recover, we cannot answer this yet."
"We can say he is fighting for his life. We judge him to be in a very serious situation. We cannot tell what the outcome will be yet. We are working hour-by-hour but it's too early to say what is going to happen and to have a prognosis.
"We think his helmet did help, without a helmet he wouldn't be here now."
"We are in constant contact with his family that are by his bedside. At this moment we don't see he is going to need a second operation."
"We have very good medical procedures and we did actually treat him very quickly and give him what he needed very quickly."
Dr Stephan Chabardes added: "The helmet wasn't enough to protect him completely but it really did help. We see a lot of head injuries like this."
Professeur Stéphane Chabarde said: "I came here not in terms of a doctor but as a friend. I'd like to thank everyone for the support and the excellent medical team who treated him so well.
"I am very worried just like his family, we are very worried about his condition. the doctors won't tell you more because they can't tell you more, they are working hour by hour.
"This kind of accident, luckily he's 45 which is better than if you were older.
A consultant added: "What we observed initially was an impact to the right side of the head. He was agitated when he came in. He had some spontaneous movements and wasn't in a normal state when he came in."