The Cerebrospinal Fluid Presentations of Neuro-Behcet Disease, A Way to Know the Ethiopathogenesis and Improve Armamentarium

Neuro-Behcet's disease (NBD) is a rare but potentially fatal manifestation of Behcet's disease. Common presentations of neuro-Behcet's disease are parenchymal (brainstem and hemispheric manifestations, meningoencephalitis, spinal cord lesions) and non-parenchymal (arterial occlusions, aneurysms, Dural sinus thrombosis). Cerebrospinal fluid (CSF) findings in parenchymal NBD usually show an inflammatory pattern with elevated cell count (usually high levels of polymorphonuclear leukocytes), high protein, and normal glucose levels, whereas the CSF findings in non-parenchymal NBD could be normal except for high opening pressure. Further investigation of CSF in parenchymal NBD has demonstrated elevated Natural killer T cells, high inflammatory chemokines, and cytokines such as Tumor Necrosis Factor-alpha (TNF-alpha), Interferon-gamma (IFN-gamma), Interleukin (IL)12, IL- 6, IL-17, IL-26, IL-15, Vascular endothelial growth factor (VEGF), Matrix metallopeptidase 9 (MMP-9), chemokine [C-X-C motif] ligand 8 (CXC-8) which indicate the role of both innate and adaptive immunity in this disease. Particularly, T helper type 1 (TH-1) and TH-17 pathways are implicated in the pathogenesis of this condition. Successful use of certain biologic agents such as TNF and IL-6 inhibitors in NBD further emphasizes the role of inflammatory cytokines in the immunopathogenesis of the disease. Drugs blocking the TH 17 pathway such as ustekinumab, secukinumab could also be applicable in the process. This review summarizes the detailed CSF findings in NBD, current understanding of the immunopathogenesis of NBD, and treatment of NBD with specific biologic agents based on our understanding of the disease pathogenesis.