The diagnostic criteria for multiple sclerosis are constantly evolving. A single, specific and sensitive marker of the disease is still lacking; therefore, the diagnosis of multiple sclerosis remains a diagnosis of exclusion. At the same time, it is crucial to start therapy with drugs that inhibit disease progression as early as possible. The successive criteria for the diagnosis of multiple sclerosis, known as the McDonald criteria, have aimed to incorporate the need for rapid disease diagnosis without compromising high sensitivity and specificity. A subsequent version of the McDonald criteria was introduced in 2017, and after 2021 new recommendations for the diagnosis of this disease had been developed by an international committee of experts. The first full version of the proposed changes was presented at the annual ECTRIMS meeting in Copenhagen on 18 September 2024. Consequently, the newest criteria are referred to as the 2024 version, although the final set was published in 2025. The most important changes are updates of the dissemination in space criteria, such as the inclusion of the optic nerve as a typical location affected by demyelinating changes in multiple sclerosis and incorporation of new magnetic resonance imaging methods. It was also proposed that the dissemination in time criterion may no longer be necessary for diagnosis, for example with the use of new methods for detecting intrathecal immunoglobulin synthesis. The committee proposed when radiologically isolated syndrome should be considered a manifestation of multiple sclerosis. Finally, the need to clarify and unify the diagnostic criteria for multiple sclerosis in individuals over 50 and under 18 years of age, and for those with primary progressive multiple sclerosis, was addressed.

multiple sclerosis, magnetic resonance imaging, diagnostic criteria, cerebrospinal fluid