S-100B. Conclusion: We conclude that follow-up investigations and calculation of ratios is a useful tool in the differential diagnosis of CJD. Variations in this pattern were observed in single cases. Abstract Background: S-100B and tau protein have a high differential diagnostic potential for the diagnosis of Creutzfeldt-Jakob disease (CJD). So far there has been only limited information available about the dynamics of these parameters in the cerebrospinal fl uid (CSF). However, there is a

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... ial interest in fi nding biochemical markers to monitor disease progression for differential diagnosis and treatment. Patients and Methods: We analyzed CSF of 45 patients with CJD and of 45 patients with other neurological diseases for tau protein and S-100B in a follow-up setting. All diagnoses of CJD were later neuropathologically verifi ed. A ratio between tau protein differences and the time between lumbar puncture was calculated. The same was done for S-100B. Results: Tau protein levels of 34 cases were above the cut-off level for CJD ( 1 1,300 pg/ml) in the fi rst CSF sample. In 7 of 11 patients with lower tau levels in the fi rst CSF sample, tau levels rose. The above-mentioned ratio was signifi cantly higher in the CJD group than in the group with other neurological diseases. Similar results were obtained for