Fractured skull forces Mason to retire
Ryan Mason insisted he had done "everything in (his) power" to play again after conceding defeat to the fractured skull injury he suffered in January 2017.
Hull midfielder Mason - who was capped once by England against Italy in 2015 - suffered a sickening clash of heads with Chelsea defender Gary Cahill at Stamford Bridge 13 months ago.
Mason described the injury as "life-threatening" and said the decision, from a medical point of view, was a "no-brainer".
The 26-year-old has been inundated with well-wishes on social media after announcing his retirement yesterday.
"I'm retiring from the game with my head held high having done everything in my power over these past 13 months to have given myself every opportunity to return to the pitch," Mason said in a statement.
"Unfortunately, having taken expert medical advice, I now have no option but to retire due to the risks involved given the nature of my injury.
"There are too many names to mention when it comes to talking about Tottenham but I would like to say a special thank you to John McDermott (head of coaching and playing development), the gaffer (Mauricio Pochettino) and everybody at Spurs for helping me to achieve my dreams.
"Finally, representing my country is an honour that nobody can ever take away from me and something that I am so proud to have achieved."
Mason also expressed his gratitude to Hull, whom he joined in August 2016 for around £13m.
Hull manager Nigel Adkins said: "I'm really disappointed for him. We wish him well and he's always welcome here."
TV presenter and ex-England and Spurs striker Gary Lineker tweeted: "A real shame for an extremely talented footballer. Wish @RyanMason all the very best."
Cahill himself tweeted: "Devastated to hear today's news from Ryan. Sending all my love to him and his family, and wishing him the best for the future."