Liverpool goalkeeper Loris Karius suffered concussion in Champions League final

Liverpool goalkeeper Loris Karius suffered a concussion in the Champions League final against Real Madrid that may have impacted his performance, Massachusetts General Hospital confirmed on Monday.

Karius, 24, made two crucial mistakes which contributed to Real Madrid's 3-1 victory in Kiev after being floored in a collision with Madrid's Sergio Ramos while defending a corner prior to Madrid's first goal early in the second half.

Liverpool's medical team were concerned about the possibility of Karius suffering a concussion in the incident with Ramos, sources told ESPN FC, and their fears were confirmed in an examination carried out in the United States last Thursday -- five days after the final.

"After carefully reviewing game film and integrating a detailed history -- including his reported present and immediate post-contact subjective symptoms -- physical examination and objective metrics, we have concluded that Mr. Karius sustained a concussion during the match," Mass General said in a statement.

"At the time of our evaluation, Mr. Karius's principal residual symptoms and objective signs suggested that visual spatial dysfunction existed and likely occurred immediately following the event. Additional symptomatic and objectively noted areas of dysfunction also persisted. It could be possible that such deficits would affect performance."

Karius collided with Ramos in the 48th minute but did not appear to receive treatment, and Real Madrid scored their first goal a little more than two minutes later. Karius tried to roll the ball out to a defender, only for Madrid striker Karim Benzema to stick out his boot and redirect the throw into the net.

The German then made a further error in the closing stages of the game, allowing a long-range effort from Gareth Bale to slip through his grasp to give Madrid a 3-1 lead.

Karius was in tears after the game and wrote an apology for his performance after being widely blamed for Liverpool's defeat. Merseyside Police said they were investigating comments and threatening posts directed at Karius on social media.

Ramos was also heavily criticised, but largely for an earlier incident that caused Liverpool star attacker Mohamed Salah to leave the game with an injured shoulder. Over 500,000 people signed an online petition for the Spain international to be punished for the play.

Karius flew to the U.S. on holiday on his return to England, but with the club determined to safeguard the player's well-being, he was sent to Boston to visit a specialist -- Dr. Ross Zafonte -- at Mass General on May 31 at the behest of the Anfield medical team, rather than at the request of the goalkeeper, a source said.

"Karius has reported significant and steady improvement since the concussive event, and we expect him to make a full recovery based on the results of the examination," the doctor's statement added. "We expect that with treatment and by following prescribed activity protocols he will continue to improve. We have encouraged vigilance and an emphasis on safety in his eventual return to full activity."

Zafonte, who penned the statement together with Dr. Lenore Herget, is a leading authority on the treatment of NFL players who have suffered head trauma. Sources said Karius was sent to visit him following consultation with Liverpool's Boston-based owners, Fenway Sports Group.

Karius, meanwhile, has remained in the U.S. for a holiday in California and will return to Liverpool for preseason training on July 2.

Liverpool declined to comment when contacted by ESPN FC.