Alex Zanardi has had a second operation as a result of the severe head injuries he suffered in a hand cycle accident.
Formula 1 driver Zanardi, afour-time Paralympic gold medallist, collided with a lorry during a race in Italy, on 19 June.
A hospital statement said the two-and-a-half-hour surgery was necessary and that his neurological condition remained "severe".
Zanardi remains in intensive care, where he is sedated and intubated a further bulletin is expected shortly.