A leading neurosurgeon believes Michael Schumacher could yet make a "favourable" recovery after confirmation he is being slowly brought out of his induced coma.

Doctors treating Schumacher at the University of Grenoble hospital have started the process of awakening the seven-times Formula One world champion, who sustained severe head injuries in a skiing accident a month ago.

Unconfirmed reports suggest the 45-year-old has responded positively to neurological tests and instructions this past week.

Although Professor Peter Hutchinson, a neurosurgeon at the University of Cambridge, warned it would be premature to read too much into the developments, there is now a degree of hope for Schumacher.

"He has been in an induced coma for a long time," said Hutchinson, speaking to Press Association Sport.

"It's unusual for it to be a month. Typically it's much shorter than that, perhaps seven to 10 days, but the French do tend to keep people under sedation for longer than we would. At some point you have to reverse that.

"It is very difficult to read at present. The drugs take time to wear off, and it would be a week or so before you could be confident the sedation has left his system.

"In terms of how he's going to be, it would be a week before it would be clearer.

"But he's fit, he's relatively young compared to some of the head injuries we treat and he was conscious immediately afterwards, which suggests it's not a devastating brain injury, so he still has the potential for a favourable outcome."

Concern had previously grown as to whether Schumacher would ever make a recovery, or even wake again, after undergoing two operations to remove blood clots from his brain in the wake of the accident.

But, in light of growing reports Schumacher was being brought out of his coma, his manager Sabine Kehm was forced to react.

Via a statement, Kehm said: "Michael's sedation is being reduced in order to allow the start of the waking-up process, which may take a long time.

"For the protection of the family, it was originally agreed by the interested parties to communicate this information only once this process was consolidated."

Kehm has stated no further updates will be given, and out of respect for Schumacher's family she has urged they continue to be left alone.

Kehm added: "The family of Michael Schumacher is again requesting for their privacy, and the medical secret, to be respected, and to not disturb the doctors treating Michael in their work.

"At the same time, the family wishes to express sincere appreciation for the sympathy they have received from around the world."