The McDonald criteria was first introduced in 2001 to allow accurate and timely MS diagnosis and the latest revision was made in 2017, based on latest research.
This criteria allows earlier diagnosis to get treatment access.
MRI evidence is used extensively to look for lesions and an MRI is encouraged if MS could be a possibility. A lumbar puncture is another key diagnostic tool as the presence of oligoclonal bands in the spinal fluid is a marker for MS. This shows that there has been disease activity in the past. You may have both or just one. This evidence is then compared with the McDonald criteria to diagnose MS.
The key requirement for MS is evidence of damage occurring at different times and to different parts of the central nervous system. However, doctors still need to use clinical judgement, e.g. diagnosing MS in children or populations where MS is uncommon