The criteria for diagnosis of multiple sclerosis are always changing as new diagnostic methods and techniques evolve.
The McDonald criteria are the diagnostic criteria widely adopted. There were significant changes from the 2005 McDonald criteria to the 2010 version, the most important being that MS could be diagnosed on the first visit to a neurologist if there was MRI evidence of more than one attack arising from more than one location in the brain.
This allowed the diagnosis to be made, contrary to what people with MS are often told, in people who had experienced only one attack and had only a single MRI scan. In effect, what was needed was just a minimum of two lesions on the first scan, with one of them being gadolinium (contrast) enhancing, indicating it was recent, versus the other(s) being older; thus this indicated at least two attacks separated in time and location in the brain.
In this new study, Dutch researchers examined how often these 2010 criteria would allow the diagnosis of MS to be made in 178 people who had had a single neurological episode (clinically isolated syndrome, CIS) consistent with MS.
Using these criteria, the diagnosis could be made at the first presentation to a doctor in 33 of the people, or 18.5%. This is of great value, as evidence shows that secondary prevention strategies, both with lifestyle changes and medication, appear to be more effective the earlier they are started.