Multiple sclerosis is the most common neurological disease in young adults characterized by recurrent relapses and/ or progression within the central nervous system. It is a complex disease in which several pathophysiological mechanisms such as axonal/ neuronal damage, demyelination, inflammation, gliosis, remyelination and repair, oxidative stres and excitotoxicity, alteration of the immune system and disruption of blood- brain barrier are involved. Biological markers; reflecting the immunopathological process, indicating responses to therapeutic interventions and optimizing therapy; are needed for the development of process- specific therapies and the prevention of disability
