Thom sustained the serious injury during a Six Nations clash against Wales in Cardiff in February.
Thom suffered a slipped neck vertebra and, despite two operations, he has been advised to give up the sport.
"I can still do pretty much anything. I just can't play a physical game such as rugby," he said.
"When you're told you can't play the sport you love dearly, it comes as quite a shock.
"I've been fortunate to have played six seasons at the top against some of the best players in the world. I'll have those memories for the rest of my life.
"You can ask any rugby player who has had a freak accident and they will still tell you that rugby is the best game in the world"
And he insisted he would continue to support his brother Max, who also plays for Glasgow and Scotland.
"Even though I can't play the game, I'll still be as enthusiastic off the pitch as I was on it," he said.
"No matter what the future holds, I know I will remain a big follower of my brother, Max, Glasgow Warriors and the Scotland team for the rest of my life."
Glasgow head coach Sean Lineen, who signed Thom from London Wasps in 2006, paid tribute to the man who turned out 73 times for the side.
"What has happened is unfortunate, but it's now in the past," he said. "I know that, whatever Thom does in the future, he will succeed.
"It's great we all had the chance to see Thom grace the rugby field and I am personally privileged to have coached him."
Scotland head coach Andy Robinson also voiced his support for Thom.
"Thom is a talented and resilient lad and, whatever challenges he decides to take on, he does so with our full backing and knowing that the rugby family will always be there to support and encourage him," he said.