Part 2

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The onset of secondary-progressive multiple sclerosis (SPMS) may be seen as the time at which progressive disability accumulation becomes clinically evident. The process of irreversible disability likely begins much earlier during the relapsing phase; however, a diagnosis is typically made only after relapses have ceased or a level of disability has been reached, which results in a considerable diagnostic delay (Katz Sand et al. Mult Scler 2014;20:1654-1657) (see also Part 1 of this article). Read More

A new study claims that Epstein-Barr virus (EBV) infection is the cause of multiple sclerosis, suggesting that people who do not acquire the virus will not develop MS (Bjornevik et al. Science 2022;375:296-301). Read More

Part 1

Secondary-progressive multiple sclerosis (SPMS) is generally defined as the onset of irreversible neurological disability in the absence of relapses in patients with a prior relapsing-remitting (RRMS) course. The invention of the SPMS phenotype has proved problematic. The pathology of RRMS and SPMS differs in degree, not kind, leading some to argue that there is no biological rationale for distinguishing phenotypes at all (Scalfari A. Mult Scler 2021;27:1002-1007). So it is not surprising that no biomarker signalling the onset of SPMS has been identified (Cree et al. Neurology 2021;97:378-388). The transition from RRMS to SPMS is of variable length, which likely reflects the limitations of detection and the diagnostic criteria used rather than the evolution of a distinct biology. The transition period is typically 2-3 years, which is the average duration of diagnostic uncertainty (Katz Sand et al. Mult Scler 2014;20:1654-1657). Read More