New Multiple Sclerosis Phenotypic Classification

BACKGROUND: In 1996, the clinical course of multiple sclerosis (MS) was characterized as relapsing-remitting, primary progressive, secondary progressive or progressive relapsing. Since then, an increased understanding of MS and its pathology prompted a re-examination of these clinical phenotypes. Main recommendations of the 2013 revisions are provided herein. SUMMARY: Clinically isolated syndrome has been added, and progressive relapsing MS has been eliminated, from the clinical course descriptions. All forms of MS should be further subcategorized as either active or non-active. Active MS is defined as the occurrence of clinical relapse or the presence of new T2 or gadolinium-enhancing lesions over a specified period of time, preferably at least one year. An additional subcategory for patients with progressive MS differentiates between those who have shown signs of disability progression over a given time period and those who have remained stable. The term 'worsening' is recommended to describe patients whose disease is advancing for any reason, whereas 'disease progression' should be reserved for those with progressive disease who are truly progressing (as opposed to worsening from a relapse). The term 'benign' should be used with caution as the course of MS can worsen at any time, even after many years of apparent stability. Key Messages: Newer characterizations of MS phenotypes include a consideration of disease activity (based on the clinical relapse rate and imaging findings) and disease progression. Accurate clinical course descriptions are useful for communication, prognostication, clinical trial design and to guide everyday clinical decision-making.