CSF/serum quotient diagram for IgG (‘Reibergram’). Individual CSF/serum ratios of IgG (QIgG) were plotted against CSF/serum albumin ratios (QAlb). Values above the upper hyperbolic discrimination line Qlim indicate intrathecal total-IgG synthesis. Individual intrathecal fractions, IgIF, can be obtained by interpolation from the percentiles above Qlim. The Reibergram plot indicated that there was no intrathecal total-IgG synthesis in the patients tested here, confirming the negative OCB results. IgG = immunoglobulin G; QIgG = CSF/serum total-IgG ratio; QAlb = CSF/serum albumin ratio. Graph created using CSF Research Tool, Comed, Germany. Open squares: Borrelia burgdorferi, Bb; upward triangles: varicella zoster virus, VZV; open circles: herpes simplex virus, HSV; filled circles: cytomegalovirus, CMV; filled squares: measles virus, MV; downward triangles: rubella virus, RV.