The 26-year-old, who won one cap for England, was involved in a horrific clash of heads with centre back Gary Cahill at Stamford Bridge in January 2017.
Mason later said it was "like a bomb going off in my head" in an interview with Sportsmail and on Tuesday revealed he is retiring following medical advice. In a long statement on Instagram Mason said, "I have worked tirelessly in order to be able to return to the pitch".
Mason - who was capped once by England against Italy in 2015 - was inundated with good luck messages on social media after confirming that his career is over.
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After the 2012 lockout, preparing for a shot at a full season with the Wings, Mursak broke his collarbone. He has played for Slovenia in the World Junior Championships and the 2014 Sochi Winter Olympics.
"I've got a son and a handsome fiancee around me, so these are the sort of things that mean more to you than football when things are put into perspective", he said.
"I'm really sad for him, it's disappointing news, disappointing for me to find out that he had to retire".
"But the consequences of the injury were so significant that he's fortunate to be where we are at this moment in time".
A HOST of Ryan Mason's former team-mates at Hull City led the tributes last night after the club's record signing announced his retirement due to the fractured skull he suffered 13 months ago.
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The inquiries are also seeking to determine whether President Donald Trump's campaign advisers colluded with the Kremlin. Trump's refusal to trust his own intelligence officials places him in the court of Russian President Vladimir Putin .
'Devastated to hear today's news from Ryan, ' the tweet read. "We wish him well and he's always welcome here".
"Of course the door is open to help him; everybody at the club loves him and all his family". "Don't worry Ryan, you're going to be a successful person outside the pitch", he says.
Headway, the brain injury association, offered its continued support, with chief executive Peter McCabe saying: "At Headway we understand the long-term impact a brain injury can have and although this hard decision must be heart-breaking for Ryan, it is a sensible one".
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White won his first Olympic gold medal at age 19 at the 2006 Turin Olympics. Speedskater Bonnie Blair won gold in the 1988, 1992 and 1994 Games.