UPDATE (GMM) Alex Zanardi on Monday remained in a "serious" condition after surgeons operated on his brain for a second time.
In a statement issued by the Santa Maria alle Scotte hospital in Siena, Italy, doctors decided to operate after carrying out a CT scan.
Zanardi, 53, has been in a coma ever since crashing into a truck during a hand-cycling race on June 19.
"The diagnostic examination showed an evolution of the patient's state, making it necessary to resort to a second neurosurgery," the hospital announced on Monday.
After the 2.5 hour operation, the former F1 driver remains "stable from the cardio-respiratory and metabolic point of view, and serious from the neurological point of view".
"The prognosis remains confidential," the hospital added.
Hospital director Roberto Gusinu said: "The intervention represented a step that had been hypothesized by the team.
"Our professionals will evaluate the evolution of the situation day by day. In agreement with the family, the next bulletin will be released in about 24 hours," he added.
06/25/20 (GMM) A doctor treating Alex Zanardi has admitted the former F1 driver's vision could be affected by his hand-cycling crash.
Italian Zanardi, who lost his legs in a 2001 Champ Car crash, is still in a coma with serious facial and head injuries in the Santa Maria alle Scotte di Siena in Italy.
We reported on Wednesday that the 53-year-old could lose his eyesight.
"We have asked an ophthalmologist for advice," said head of emergency medicine Dr Sabino Scolletta.
And one of the first emergency specialists to treat Zanardi, Dr Robusto Biagioni, said: "Without treatment, Zanardi would only have had minutes to live.
"My colleagues found him deeply unconscious, with brief moments of unrest. He moved his arms and shouted incoherently.
"His face was marked by broken bones and what worried us most at the start was a very bad right eye injury. It was also clear that he had broken his skull," Dr Biagioni added.
But for Zanardi's fans, he gives some hope.
"I have seen worse injuries in my career and these patients recovered, often contrary to our forecasts. We cannot give up hope for Alex Zanardi.
"He is a model athlete and everyone knows how strong his will to survive and his determination are."
Finally, the hospital said it has been advised by Zanardi's family that no further medical updates will be provided "until there are significant changes in his state of health".
06/23/20 (GMM) Alex Zanardi's brain injuries do not compare with those suffered by fellow former F1 driver Michael Schumacher.
That is the claim of Giuseppe Olivieri, the doctor who operated on Zanardi following his head-on crash with a truck during a hand cycling race in Italy last weekend.
2-time CART IndyCar champion and former Williams driver Zanardi, who lost his legs in a 2001 Champ Car crash, has spent a third night in a coma and on a ventilator, with Olivieri saying his condition is "serious".
"We won't see what his neurological state is until he wakes up – if he wakes up," he said. "Serious condition means it's a situation when someone could die."
However, Olivieri has told La Gazzetta dello Sport that Zanardi's injuries – to his forehead, face and eyes – "are less than those of Michael Schumacher".
Almost nothing is known publicly about Schumacher's condition, but the seven time world champion has not been publicly seen or heard from since striking his head on a rock while skiing in 2013.
"Diffuse axonal damage is a very extensive injury throughout the cerebral cortex, from which there is little chance of returning to normal cognitive and motor functions," Olivieri said.
"At least from what we as doctors can understand for now, Zanardi does not suffer from this injury," he added.
"The point of impact is not what counts. What matters is the internal injuries and how much damage has spread within the skull."
Olivieri said it is still too early to attempt to wake the 53-year-old Italian.
"In injuries of this type, it takes a few days to start waking up the patient and assessing the damage. A week or maybe two," he said.
"We are talking about a fragile patient who has suffered a major head injury, so you have to be very careful. The fact that he is an athlete and in such good physical condition is a cause for optimism."