LONDON (AP) -- Nearly two months after Michael Schumacher suffered serious head injuries in a skiing accident and was placed in a drug-induced coma, some neurologists say the seven-time Formula One champion seems unlikely to make a full recovery.
The 45-year-old Schumacher fell while skiing in France and hit the right side of his head on a rock, cracking his helmet. Doctors operated to remove blood clots from his brain but some were left because they were too deeply embedded.
Schumacher's condition stabilized after he was placed in the coma. Late last month, doctors began the process of withdrawing sedatives to try to wake him up.
His agent, Sabine Kehm, said in an email on Friday that "Michael is still in the wake-up phase" and that "this phase can be long." Schumacher's family has released few details of his condition to protect his privacy.
"It does not bode well," said Dr. Tipu Aziz, professor of neurosurgery at Oxford University who is not connected to Schumacher's care. "The fact that he hasn't woken up implies that the injury has been extremely severe and that a full recovery is improbable."
Patients who have had major head injuries are sometimes put in a drug-induced coma to give the brain a chance to heal; a coma reduces the need for blood flow and may help the swelling go down.
Aziz said doctors typically try every few days to bring someone out of a coma.
"If you don't start getting any positive signs, that becomes very worrisome," he said, adding that Schumacher's doctors are probably doing regular brain scans to look for signs of activity -- though such signs may be difficult to detect if he is still being sedated.
Other experts said it was premature to make an accurate prognosis.
"About 90 percent of the recovery is made within nine to 12 months, so this is still early days," said Dr. Anthony Strong, an emeritus chair in neurosurgery at King's College London. "The longer someone is in a coma, the worse their recovery tends to be."
Now that several weeks have passed since the accident, doctors may also have a better idea of how the rest of Schumacher's brain is doing.
"MRI scans can show any secondary deterioration in the brain structure," said Dr. Colin Shieff, a neurosurgeon at the National Hospital for Neurology and Neurosurgery in London and a trustee for Headway, a British brain injury charity.
He said other parts of Schumacher's brain that weren't directly affected by the accident might now be starting to show worrying signs that may not have been visible before.
Shieff said that if Schumacher does eventually come out of the coma, he probably would face significant disabilities because of the length of time he has already spent comatose.
While there have been rare instances of people emerging from comas months and years later with the ability to communicate, Shieff was doubtful that would be the case with Schumacher. He said the cases where comatose people made a surprising recovery had mostly suffered things like poisoning, strokes or failed resuscitation attempts.
Associated Press writer Geir Moulson in Berlin contributed to this report.