ABSTRACT
Approximately 85% of multiple sclerosis (MS) patients present with a relapsing-remitting (RR) course, in which there are acute relapses followed by partial or complete recovery1. By definition, clinical manifestations are stable between relapses. In most patients, the course eventually evolves into gradual progression with or without superimposed relapses, minor remissions and plateaus, termed secondary progressive MS (SPMS)1. The transition from RRMS to SPMS is typically rather insidious and occurs over several years. SPMS has been distinguished from primary progressive MS (PPMS)2
in which patients exhibit gradual worsening from disease onset without relapses (see Chapter 43). In PPMS, the patients tend to have an older age of onset, and relatively more men are affected. Magnetic resonance imaging (MRI) demonstrates fewer and less distinct cerebral lesions, a paucity of new lesions over time despite increasing disability and less gadolinium (Gd) enhancement3.
