Evolution of McDonald’s criteria

The McDonald criteria used to diagnose multiple sclerosis have evolved over the past quarter century. They were first promulgated in 2001, and every few years they are revised, allowing to increase the sensitivity and specificity of the criteria and to accelerate the diagnosis of the disease, which significantly affects the earlier inclusion of appropriate disease-modifying therapies. The latest modification was presented at this year’s ECTRIMS congress in September 2024. The basic tenets of the changes to the McDonald criteria include: recognition of a history of relapses as equivalent to clinically isolated syndrome, recognition of radiologically isolated syndrome as a specific situation of multiple sclerosis, inclusion of the optic nerve as the fifth topographic location of lesions typical of multiple sclerosis, and abandonment of the criterion of spread over time as a prerequisite for the diagnosis of multiple sclerosis. In terms of both laboratory and neuroimaging diagnosis, new diagnostic tools have been proposed: central vein sign and paramagnetic rim enhancement lesions on magnetic resonance imaging and the presence of kappa free light chains in cerebrospinal fluid. The use of the newly proposed criteria for diagnosing MS allows for easier diagnosis of the disease in selected patients and diagnosis of the disease for patients who could not be diagnosed with multiple sclerosis based on previous criteria.