Multiple sclerosis, and other demyelinating and autoimmune inflammatory diseases of the central nervous system.

Multiple sclerosis (MS) is characterized by a substantial degree of heterogeneity in relation to clinical manifestations, disease course, radiologic findings, histopathologic characteristics of brain lesions, and response to treatment. In this scenario, there is a strong need in MS for biomarkers that reliably capture these diverse aspects of disease heterogeneity and assist, for instance, in disease diagnosis and stratification, in the prediction of disease course, or in the identification of new and effective therapies for the disease. Due to its close proximity to sites of inflammatory lesions, biomarkers measured in cerebrospinal fluid (CSF) are likely to be more informative compared to other body fluid sources such as peripheral blood or urine. This chapter will review the current knowledge existing on CSF molecular biomarkers in MS and also neuromyelitis optica, a pathologic condition originally considered to be a form of MS, following a classification of biomarkers based on the predominant pathophysiologic processes taking place in these two diseases: activation/inflammatory biomarkers; oxidative stress biomarkers; neuroaxonal damage biomarkers; and remyelination and demyelination biomarkers.