Another issue of great clinical significance that is not addressed by 2010 McDonald criteria is subclinical disease. 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). Some of these people will develop MS even after several years. Because early initiation of MS disease-modifying therapy is associated with better clinical outcomes, it is important to identify individuals in the subclinical stage of disease and determine if initiation of treatment at this stage is beneficial. More research is currently being conducted to clarify this issue and address which RIS patients will progress to definite MS. Depending on the findings of this research, future criteria might address this controversial but highly important issue of MS care.