FORMER Worcester Warriors player Andries Pretorius knew his rugby career was over when he could not prevent himself from falling down the stairs.

As Pretorius lay in a crumpled heap at home, the ceiling above was not his only view. He was finally facing up to the warning signs which had flashed soon after his move from Cardiff Blues to Worcester last summer.

“Sportsmen are very good at not telling physios or club officials the full story when it comes to injuries,” Pretorius said.

“You see it with concussion now, mental toughness tells you to keep going, but I knew rugby was over at that moment. I was only hurting myself and my family if I tried to carry on. It had to stop.”

He retired from professional rugby at the end of January after failing to make a first team appearance for Warriors.

He is coming to terms with a life-changing auto-immune condition called neuromyotonia. Or Isaacs Syndrome.

Isaacs Syndrome is so rare it can often be years before a correct diagnosis is made.

Yet its effects can be crippling with constant muscle cramps leaving patients immobile in more serious cases.

Pretorius said: “Your antibody score should be between nought and 10, mine was 166. They’d never seen it that big before.

“The first signs were when I pulled my calf in my second training session at Worcester.

"When you pull a muscle you’re either running at full tilt, you’ve got an explosive movement in those first two steps, or it’s the last five steps to slow down.

“But in my case it happened just before the halfway point of warming up, I started getting a cramp which just wouldn’t let go.

“It was a bit unusual but I just powered through until I got the cramp again in Portugal on a pre-season trip.

"I had it scanned back in Worcester and a small tear in the calf was detected and the following week I did the other side.

“A week after that I was doing weights and I tore a mus - cle in my pec (pectoral muscle), again it was not as if I was exerting myself.”

He went to see a nerve spe - cialist who observed that even when Pretorius was relaxing his muscles were twitching.

At the time he was still training, getting on the bike and spending time in an altitude chamber as he tried, in his own words, to “push through” the problem.

But then came that nasty fall when he was unable to save himself from tumbling backwards down the stairs.

“I’d torn my calf and was limping and as I was climb - ing the stairs my other calf cramped,” Pretorius said.

“I tried to grab onto the rail but my pec cramped and I fell head over backwards and down the stairs. That was the moment I realised this was something I wasn’t going to be able to manage.

“I was at home and wasn’t even fatigued. Until then I had been saying ‘I can win this’ but now it was so bad I had to accept what was hap - pening. I was in a bad place mentally and physically.”

Pretorius was sent to see a neurologist and a blood test confirmed Isaacs Syndrome.

After four months of not knowing what was going on there was relief a diagnosis had finally been made, yet the news informed him of the challenges ahead.

In March he went into hospital again for a nine-day spell and high dosages for a longer period but still his muscles twitch, and the future remains uncertain with steroid injections and dialysis drastic courses of action should the condition worsen.