"He is still in intensive care and suffered a severe polytrauma, resulting in very serious brain damage", the hospital added. Italian media quoted the hospital as saying on Wednesday that Hayden had suffered a cerebral edema and lower body fractures and surgery had not been possible immediately because of his condition.
Nicky Hayden was the 2006 World Champion with Honda, beating Sprint Valentino Rossi.
"Following the incident, Nicky was treated on site by medical staff and then taken by ambulance to a hospital near Rimini for immediate treatment", Red Bull Honda said in a statement.
The American, who has been racing for Red Bull Honda's World Superbike team, collided with a auto near Rimini Wednesday.
Former MotoGP world champion Nicky Hayden is in a "extremely critical" condition in intensive care after a cycling accident in Italy.
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"The clinical conditions of Nicky Hayden, hospitalized on Wednesday, May 17, remain extremely serious in the hospital resuscitation department of the Bufalini hospital in Cesena", a statement read.
American motorcycle racer Nic.
Hayden's fiance Jackie, his brother Tommy, and mother Rose have also arrived in Italy to be by his side in these hard moments. This incident took place in Rimini in Italy, this Wednesday afternoon, and the site of a auto after that collision, shows the horrific intensity of this crash. He was transported to a local hospital before being moved to Cesena. He competed in Moto GP from 2003-2015.
"More updates will come as soon as they are announced".
The dangers of training on public roads have been highlighted in recent weeks by other accidents affecting professional athletes.