Ben Leahy, 20, was diagnosed with the disease in 2008 and lost the ability to stand within a few months.

However, a new procedure to combat the disease has helped him regain his health and he is now walking again. The treatment targets the immune system of multiple sclerosis patients, which turns in on it causing damage to nerves which can lead to blurred vision, loss of balance and paralysis.

Doctors carried out a new technique to remove stem cells from his bone marrow before using chemicals to destroy all his immune cells.

The stem cells were then transplanted back into Mr. Leahy’s body to replenish the immune system – effectively resetting it and the positive results had surprised doctors. “At the moment there’s a good chance we may have arrested the disease,”

“He walks pretty well, there’s only some mild weakness in his right leg and some visual loss in one eye and apart from that he’s very intact.”

But improvements in the techniques meant the risk was now one per cent and the outstanding results of Mr. Leahy’s treatment meant it could be used on more patients in the future. “It sets another landmark for people to work towards,” he said.

For some patients there would be a 60 to 80 per cent chance that the progress of the disease could be stopped and many would have a good chance of their symptoms being reversed. Mr. Leahy’s mother Prue, who was afraid her son was going to die, said she did not expect to see him walking again.

“What I got was more than I could have ever imagined or hoped for,” she said.

Mr. Leahy is now planning to return to school and hopes to study physics.

His case is not the first time stem cell injections have been used to reverse the symptoms of MS but the remarkable success of his treatment suggests the procedure could become more widespread. In results reported in the Lancet, some patients in the trial were left free from seizures and better able to walk after the treatment. Last year experts suggested that stem cell therapy could be a “cure” for MS.