Prior to the onset of demyelination in multiple sclerosis (MS), early oligodendrocyte injury, axonal degeneration and astroglial scarring occur. The irreversible progressive phase of MS begins when the axonal loss threshold is reached. Progressive disease onset has the highest impact on a poor prognosis in MS. Conversion to progressive disease is essentially an age-dependent process independent of disease duration and initial disease course. Although prevention of relapses has been the primary approach in the disease management, incomplete recovery from even the first relapse correlates with the long-term neurodegenerative phenotype of progressive MS onset. Therefore, the provider should review each patient's potential for relapse-related disability and start DMDs with the goal of preventing relapses. Existing immunomodulatory medications used to prevent MS relapses do not prevent long-term disability, which requires agents focused on remyelination and axonal repair. If applied immediately after a relapse rather than during the progressive phase of MS, remyelination-stimulating strategies may result in full recovery and prevention of long-term neurodegeneration and progressive disease course.
Keywords: Axonal degeneration; Progressive MS; Remyelination.