Alex Zanardi's condition is "serious but stable" two days after a second operation on head injuries suffered in a hand cycle accident.
The 53-year-old, a former Formula 1 driver turned four-time Paralympic gold medallist, collided with a lorry during a race in Pienza, Italy, on 19 June.
A statement from the hospital in Siena said Italian Zanardi remains sedated and intubated.
Further updates will be provided if there are "significant developments".
Zanardi has become a global sporting icon for the strength of will and determination he has shown in overcoming adversity in his career, after he lost both his legs in an accident while racing in a Champ Car event in Germany in 2001.
He drove in F1 from 1991-94 and in 1999 - for the Jordan, Minardi, Lotus and Williams teams - scoring a best result of sixth place.
Zanardi raced in the United States-based Champ Car series from 1996-98, winning the title in 1997 and 1998.
He returned to Champ Cars in 2001, when he had the accident at Germany's Lausitzring.
After extensive rehabilitation, he returned to motorsport in 2005, spending four years racing for BMW in the World Touring Car Championship, and winning four races.
He then turned to hand-cycling, in which he has won 12 world championships in addition to his four Paralympic gold medals, as well as the New York City marathon in 2011.