Multiple Sclerosis Categories There has been a recent standardization of disease category terminology to describe the pattern and course of multiple sclerosis: Relapsing-remitting (RR) MS: Clearly defined relapses with full recovery or with sequelae and residual deficit upon recovery; the periods between disease relapses are characterized by a lack of disease progression. Secondary-progressive (SP) MS: Initial RR disease course followed by progression with or without occasional relapses, minor remissions, and plateaus. Primary-progressive (PP) MS: Disease progression from onset with occasional plateaus and temporary minor improvements allowed. Progressive-relapsing (PR) MS: Progressive disease from onset, with clear acute relapses, with or without full recovery; the periods between relapses are characterized by continuing progression. There are also two severity outcomes described: Benign MS: Disease in which the patient remains fully functional in all neurologic systems 15 years after disease onset. Malignant MS: Disease with a rapid progressive course, leading to significant disability in multiple neurologic systems or death in a relatively short time after disease onset.