Primary Progressive Multiple Sclerosis Evolving From Radiologically Isolated Syndrome.

Objective: The aim of this work was to evaluate the preprogressive phase in subjects with radiologically isolated syndrome (RIS) who evolve to primary progressive multiple sclerosis (PPMS).

Methods: A multicenter RIS cohort was previously established. Demographic, clinical, and radiological characteristics of subjects with RIS that evolved directly to PPMS were compared to those that developed a relapsing disease course from onset (clinically isolated syndrome [CIS] or relapsing-remitting MS) and were also compared to two other population- and clinic-based PPMS cohorts.