BBB in Inflammatory CNS Disorders

sclerosis(MS) is an inflammatory disorder of the central nervous system with an increasing rate of prevalence in IRAN during last decade.MS clearly results from the blood brain barrier(BBB) breakage and the resulting cellular damage and inflammatory process. BBB disruption and vascular changes play an important role in MS pathogenesis. Vascular pathology in a background of genetically predisposed individual,influenced by several environmental factors such as pathogens, Vit D deficiency, obesity and smoking, may be a critical initiator of a series of events including hypoxia, protein deposition and immune cell egress that allows the development of a CNS-specific immune response and combination of inflammation and degeneration two types of inflammatory process occur in MS, which develop in parallel but partiallyindependent from each other. The first of them is invasion of T- and B-lymphocytes with profound blood brain barrier leakage, which predominately affects the white matter, and which gives rise to classical active plaques. The second type of inflammation is a slowaccumulation of T-cells and B-cells in the absence of major blood brain barrier damage in the connective tissue spaces of the brain, such as the meninges and the large perivascular Virchow Robin spaces, where they form structures in part resembling tertiary lymphfollicles. in this type of inflammation B cells have important role and inflammation lead to formation of subapical demyelinated lesions in the cerebral cortex, with slow expansion of pre-existing lesions in the white matter and with diffuse neurodegeneration in thenormal appearing white or gray matter. The first type of inflammation dominates in acute and relapsing MS. The second type of inflammation is already present in early stages of MS, but gradually increases with disease duration and patient age in progresive types of MS.Presence or absence of inflammationis a key point in choosing drugs and monitoring the treatment response. MRI represents the most sensitive non-invasive tool to monitor inflammation in the clinical practice.In the early phase of inflammation MRI also detects new lesions asextrusion of gadolinium contrast agents across the BBB. according to MC Donald criteria 2017 The occurrence of MRI lesions is used to confirm diagnosis and has been validated as surrogate marker of relapse to monitor response to treatments. New imaging techniques havebeen developed to study diffuse inflammation taking place outside the focal plaques.