Clinical Features and Natural History of Multiple Sclerosis: The Nature of the Beast

This chapter focuses on natural history studies, early clini­cal predictors of disability outcome and their application to an individual patient, and the controversy surrounding the entity of benign multiple sclerosis (MS). New ap­proaches to data set analysis with emphasis on age at disability milestones are discussed. Natural history studies have focused on the time from onset or diagnosis of the disease to the assignment of one of the expanded disability status scale (EDSS) scores; these data provide informa­tion regarding the rate of disability progression. A formal classification of MS disease subtypes widely accepted is: relapsing-remitting (RR), secondary progressive (SP), primary progressive (PP), and progressive relapsing (PR). Patients with an RR course take a longer time from onset to reach disabil­ity milestones than do patients with an initially progressive course. A multitude of demographic and clinical variables including female gender, a younger age at onset, sensory symptoms, and optic neuritis are associated. Prognostic variables associated with a poor outcome have included male gender; onset with motor, sphincter, or cerebellar features; poor recov­ery from initial or early attacks; higher attack rate in the first 5 years; and a progressive course. Disease-modifying agents (DMAs) have been shown in large, randomized con­trolled trials to reduce the relapse rate, and to reduce the accrual of lesions identified on magnetic resonance imaging.