ST KILDA midfielder Koby Stevens has revealed the toll recent concussions have had on his life after he was ruled out for the remainder of the season last week.

The 26-year-old admitted a recent scan showing changes to his brain had confronted him most after two serious head knocks in his past five games.

Stevens suffered a head clash against Brisbane in round one before playing just six days later against North Melbourne on Good Friday, despite carrying symptoms into the game.

"I'd just come back into the side, so I obviously didn't want to speak up and we had a pretty big game that Friday against North Melbourne and I just went out and played," Stevens told Fox Footy.

"It wasn't until that next week when I was really bad, I felt really ill.

"It wasn't great, I went into the doctors and (sought) some more advice after that.

"I was pretty good in the early days, but we had a scan result come back that suggested that I did have changes to my brain.

"I was pretty hurt as it was pretty tough to take. I've taken hits, come back from them strong, but to have someone say there's been changes to my brain and they can't really tell you what they are, they're just there, it's tough."

Up until last week Stevens had been spending short periods at RSEA Park before coming to a decision with the club to put a line through the rest of the season.

"It's a day-to-day thing. Some days I wake up and I'm pretty clear and then I try to do a little bit of exercise and as soon as my heart-rate gets up, I just get real chronic headache and pretty dizzy," he said.

"I haven't run or touched a footy in eight weeks, so it's been pretty difficult and frustrating."

Stevens also spoke of the alarming effects a round 21 head clash with fellow concussion victim Angus Brayshaw had on him last year.

Incredibly, after being ruled out of the match, he backed up the week later and played the final two matches of the season.

"I reckon that one was the worst one I've ever had," Stevens said.

"I wasn't knocked out, but it felt like a bomb had gone off.

"I couldn't hear anything, and it hit me right in the ear drum, so for about 10 to 15 minutes I had ringing in my ears.

"I quickly ran off after that but then something happened on the field. There was a quick sub that had to be made, so I just ran back out, but I had no balance.

"I was leaning to one side where I'd been hit and was about to fall over, so I knew something was pretty bad then."

Stevens also said he had put his university studies on hold for the short-term as he deals with the fallout of his hits.