[4] The McDonald criteria maintained a scheme for diagnosing MS based solely on clinical grounds but also proposed for the first time that when clinical evidence is lacking, magnetic resonance imaging (MRI) findings can serve as surrogates for dissemination in space (DIS) and/or time (DIT) to diagnose MS.[5] The criteria try to prove the existence of demyelinating lesions, by image or by their effects, showing that they occur in different areas of the nervous system (DIS) and that they accumulate over time (DIT).

[5] The McDonald criteria for the diagnosis of multiple sclerosis were revised first in 2005 to clarify exactly what is meant by an "attack", "dissemination" and a "positive MRI", etc.

As of 2017 revision The term ‘possible MS’ was added for people with a typical clinically isolated syndrome who did not meet the criteria.

In order to reduce false positives, McDonald et al. propose that their criteria should be applied only after any other disease has been ruled out.

[11] McDonald criteria have been shown to have a low sensitivity and specificity (with respect to the pathological presence of lesions) in Asiatic populations.

In 2010, the International Panel on Diagnosis of MS met in Dublin, Ireland for a third time to discuss and revise the McDonald diagnostic criteria.

Another promising MRI technique is magnetic transfer imaging, which will allow the detection of damage in normal-appearing brain tissue away from focal lesions.

[5] Four biomarkers were identified for further study by the 2010 revisions of McDonald Criteria: The CSF,[20] the serum anti-GAGA4[21] and protein signatures[22] and finally the circulating microRNA[23] Some blood tests have been proposed based in circulating neurofilament light chain (NFL), in RNA profiling[24] or in the MRZ reaction.

There are some patients who were incidentally found to have brain lesions with appearance and location consistent with MS who are now classified as having a radiologically isolated syndrome (RIS).

Depending on the findings of this research, future criteria might address this controversial but highly important issue of MS care.