AbstractBackgroundThere are still insufficient quantitative comparisons of phase‐dependent blood–brain barrier permeability among inflammatory central nervous system disorders.AimBy using the Reibergram (2‐D diagram of the quotient of albumin and quotient of immunoglobulin G), we visually compared the extent of blood–brain barrier permeability among inflammatory central nervous system disorders.MethodsBoth the quotient of albumin and that of immunoglobulin G in the acute and chronic phase were calculated in non‐herpetic meningitis, septic meningitis, multiple sclerosis and neuromyelitis optica, and were plotted on the Reibergram. As controls, samples from non‐inflammatory patients without pleocytosis were collected. The correlation coefficient between each cerebrospinal fluid biomarker and disease severity index in each disorder was also studied.ResultsIn the controls, the distribution differed between males and females, suggesting a sex‐dependent difference in blood–brain barrier‐function, in addition to the age‐related compromise. A compromised blood–brain barrier was confirmed in the acute phase of meningitis and neuromyelitis optica, but not in the acute phase of multiple sclerosis. However, blood–brain barrier permeability significantly correlated with the severity and disability in multiple sclerosis. In meningitis, a compromised blood–brain barrier correlated well with the length of hospitalization rather than cerebrospinal fluid cell count.ConclusionVisualization of the blood–brain barrier permeability with a Reibergram indicated distinct pathophysiology in each disorder. The quotient of albumin and quotient of immunoglobulin G would be useful for estimating the pathophysiology in each disorder, and the severity of ongoing inflammation or damage in the central nervous system.