'YOU know in the movies, when someone is shot with a tranquiliser gun and they hit the floor and sound drunk when they try to talk?

It was like that . . . " The passing of almost six years has not helped Kerry Steel hone her explanation, but neither has it dulled her memories of the night that changed her life.

She was 18, in her first year at Glasgow University and widely considered to be one of Scotland's most promising athletes. Her seamless progression from junior to senior international level in sprints, long jump and triple jump was such that she was invited to an elite training session with double Olympic gold medallist Michael Johnston. The Commonwealth Games qualification standards appeared a formality so she was touted as a likely medallist as part of Glasgow's bid to host the 2014 event.

Then it was all snatched away from her. "I went to go to bed and suddenly felt horrendous - really sick, exhausted, drained - almost as if I'd gone from being fine to having the flu inside a minute," Steel recalls.

"Within 10 minutes, this sensation travelled down my left-hand side then back up my right and I felt totally paralysed. It was absolutely terrifying."

That fear was compounded when the doctors were unable to identify what was wrong with her. Thankfully, Steel's speech returned to normal after a fraught night in hospital but full movement took longer to regain and the next couple of months were spent sleeping 16 hours a day.

It was a further 10 weeks before she was physically able to train but the mental wounds would take even longer to heal, as persistent problems with her hamstrings and ankle became an insurmountable psychological barrier. "Every slight niggle was a huge battle," she says of a period during which both of her grandfathers died, as well as three childhood friends.

"Thinking back, I over-trained, didn't eat properly and didn't rehab injuries as I should have but it just felt like everything was falling apart. I'd be an emotional wreck, crying buckets of tears and having panic attacks. I was putting on a cheery face but behind closed doors I was asking my mum Hilary to take me to see someone because I was getting so down and pushing away anyone who was trying to help me. I didn't know how to make it better and that made me feel stupid."

It became apparent that her athletics aspirations were over but what remained unclear was what had actually happened to her. To this day, Steel suffers "an episode" once or twice a year, during which she will be paralysed for up to 15 minutes and will suffer slurred speech, confusion and blurred eyesight. After a couple of days of exhaustion, she will be return to normal.

Despite a battery of tests on everything from her brain to her heart and notions of strokes, MS and a rare form of epilepsy, the condition remains undiagnosed, save for suggestions that it may be a dormant viral infection that flares up from time to time.

For a while, the attacks were pre-empted by migraines so severe that she struggled to recognise people and a change in her sense of smell. Until her most recent incidence, she would feel ill for five or 10 minutes beforehand, but this time she was flat out within seconds - a development that has caused her to lose her driving licence lest it happened again when she was at the wheel. "That's the worst thing," she says. "Losing my independence. That and not knowing what it is, but it's just something I have to deal with. I mean, it's okay . . . I'm not infected!

"I know not to get worried now; it's almost a case of 'here we go again'. It doesn't massively affect me, although I've been a wee bit on edge recently whenever I've felt a little bit unwell because it's not long since my last attack, when I had 10 in one day and they were all instant. But the time before that was January 2013 so you can't live thinking something is going to happen every day because you would go crazy."

Besides, she has plenty of other things to occupy her mind. Having returned to university to complete her physiology degree, she opened Kerry Steel Massage in her home town of Ayr and enhanced her rugby links - her father Grant captained Glasgow in their 1984 victory over the touring Australians and brother Craig emulated him by playing for Ayr - by working with the likes of the Scotland sevens rugby squad as well as the Wallabies and All Blacks from the XV-a-side game and assorted Olympians.

Furthermore, she has been assigned a position as a sports massage practitioner in the athletes' village at the Commonwealth Games. "It's not the way I wanted to be there but I would rather be there in some way than not be involved at all," she says, with a smile.

"I'm not going to be an emotional wreck and break down when I'm treating people," she says, laughing at the image of her bawling her eyes out in front of Usain Bolt.

"Sure, I still find it hard to watch athletics because you see all your friends on TV and, worse, people who you used to beat making it to major events. I find myself thinking 'should I have let this take over?' and every time I go through the motions of vowing to get back down to the track and digging out my old training programmes. Sometimes I do it for a couple of months until I get another niggle and I walk away again but that feeling of wanting to will never go away.

"But I think I'm beginning to get past it. I can watch athletics now without crying . . ."