Trials, published in the New England Journal of Medicine found that a new drug called Ocrelizumab is the first drug shown to work in the primary progressive form of the disease.

The drug is currently being reviewed for use in the US and Europe.

Multiple sclerosis is caused by a rogue immune system mistaking part of the brain for a hostile invader and attacking it.

It destroys the protective coating that wraps round nerves called the myelin sheath.The sheath also acts like wire insulation to help electrical signals travel down the nerve.

If these sheaths are damaged it prevents nerves from working correctly and means messages struggle to get from the brain to the body. This can lead to having difficulty walking, fatigue and also blurred vision.

Ocrelizumab kills a part of the immune system - called B cells - which are involved in the assault on the myelin sheath.

In 732 patients with progressive MS, the percentage of patients that had deteriorated fell from 39% without treatment to 33% with ocrelizumab .

Patients taking the drug also scored better on the time needed to walk 25 feet and had less brain loss detected on scans.

The Chief Executive of MS Ireland said in a recent statement "MS Ireland believes that people with MS should have access to all and any appropriate and licensed treatments that would improve or assist in the management of their condition."