After his December 29 fall at Meribel ski resort in the French Alps, Schumacher was sedated and his body temperature cooled to about 35 degrees to ease the risk of further damage to the brain.Surgeons at Grenoble University Hospital say they decided on the coma after operating on bleeding and bruising in Schumacher's brain.They carried out a post-operative scan that revealed "widespread lesions" on both sides of the brain.A second operation, to treat bleeding, took place on December 30.There has been no update on his condition since January 17, when his spokesman Sabine Kehm said he was still "stable" and that his family had complete trust in his treatment.Drivers Lewis Hamilton and Nico Rosberg unveiled Mercedes' silver-and-turquoise W05 before the first session of the pre-season began at the Jerez track in southern Spain.The upper part of its chassis just behind the driver's seat carries the Twitter hashtag #KeepFightingMichael.Four-time formula one champion Sebastian Vettel said on Tuesday he was hoping for a "miracle and he can be the same guy he was before"."We still don't know what shape he will be in when he wakes up, which is awful for his family and friends," Vettel told reporters in Jerez."I have known him for a long time and have been looking up to him all my life," Vettel said."I got to know him obviously when he did his comeback a little bit more and became his friend."And Niki Lauda, a three-time formula one world champion, added: "Michael, every day I follow your improvements and every day I am close to you. I hope I can speak to you very, very soon!"Medical experts underlined how complicated cases like Schumacher's can be."A blow to the head causes bruising, a swelling, which takes place in a confined space, the skull, which leads to pressure on the brain," said Gerard Audibert, a professor of neurosurgery at the University Hospital Centre in Nancy, eastern France."One way to control it is to ensure that the patient and the brain are at rest and to control his ventilation, using an artificial respirator to oxygenate his brain."It's quite rare for a coma to be induced for more than three weeks, he said.Artificial comas "can last a long time, days or weeks", said Professor Jean Mantz, in charge of anaesthesia at the intensive care unit at Bichat-Beaujon-Louis Mourier Hospital in Paris.Once pressure within the skull has stabilised at a normal level, sedation levels are scaled back and the patient returns to consciousness, but "it's not unexceptional for a patient not to revive", Audibert said."There are all sorts of ways of testing the patient for responses, but nothing replaces physical contact," said Bernard Vigue of the University Hospital Centre at Bicetre, in the southern Paris suburbs."It starts with simple requests, such as 'squeeze my hand'."In accidents of a similar severity, patients often had a disability after their emergence from coma, the experts noted."Recovery can be a very long road. In some case, patients improve between a year and three years later," said Vigue.Schumacher, who turned 45 on January 3, dominated formula one.He won the formula one title seven times, more than any other driver, and notched up 91 victories between 1994 and 2004.He first retired aged 37 but was unable to resist the lure of the track. In 2010, he came out of retirement but was unable to recover his previous performance and quit for good in 2012.As a formula one racer, Schumacher was known for his daring overtaking manoeuvres, his at-times almost reckless abandon in the pursuit of victory and his mastery of tricky conditions presented by rain.On that fateful day at the Meribel resort, Schumacher appears to have skied on a partially covered rock, lost his balance and fallen on another rock further down, according to the prosecutor in charge of the probe.The impact was so strong it smashed his helmet in two.Investigators have ruled out faulty skis, inadequate signage or excessive speed as possible causes.(smh.com.au)ANN.Az