Motegi MotoGP: De Angelis sustained chest, back injuries in crash

The fourth practice session just before Japanese Grand Prix qualifying had to be red-flagged on Saturday after de Angelis had his violent accident.

He was transferred by helicopter to Dokkyo Hospital in Mibu, where a lung contusion, multiple fractured ribs and a total of seven vertebrae fractures were diagnosed.

The 31-year-old Italian was also knocked unconscious in the crash.

MotoGP medical director Michele Macchiagodena said de Angelis's injuries would to be closely monitored for any further effects and to decide if surgery will be required.

"There's a thoracic trauma with bilateral ribs fracture, on the left and the right," Macchiagodena said.

"He also suffered a head concussion - the CT scan doesn't demonstrate any damage or bleeding but it still requires him to remain under observation for the next days.

"However what needs more attention is the fact he sustained a lung contusion - we'll have to monitor it closely to make sure it doesn't lead to restricted breathing or any kind of infection."

A MotoGP statement described de Angelis's back injuries as "fractures to the T7-T8-T9 vertebrae, a body fracture to L4 and trasversal process fractures to T2,4 and 8".

Macchiagodena added: "As of now there's no neurological damage but we'll have to make sure those fractures are stable so the medulla isn't affected.

"For now it needs to be observed closely in order to determine if surgery can be avoided."

De Angelis had been contesting his first full MotoGP season in five years on underdog team Ioda's Aprilia in 2015.

He had focused on Moto2 in recent years following an initial two-season campaign in MotoGP with Gresini in 2008-09, although he had made various stand-in appearances in the premier class with Interwetten, Pramac and Forward in the interim.

Details of how de Angelis's crash occurred remain unclear, with no footage of the accident broadcast, but he appeared to have lost control on the exit of Turn 9 and gone across the track into the metal barriers.