Clear and colorless cerebrospinal fluid among suspected central nervous system infections

Abstract

Introduction: The physical examination of the cerebrospinal fluid (CSF) is part of its routine evaluation and is easily performed as soon as CSF is obtained. However, its predictive value of CSF abnormalities is poorly known. Objective: In this study we evaluated the predictive value for CSF abnormalities leukocytes count among clear and colorless CSF in cases of suspected central nervous system (CNS) infection. Methods: We retrospectively evaluated data from CSF samples collected from suspected CNS infection that were classified as clear and colorless. This visual categorization was performed by the collector physician and by biomedical staff experienced in CSF analysis. The CSF cell count were considered normal when CSF white blood cells were up to 3 cells/mm3 , protein was below 45 mg/dL, glucose above 50 mg/dL, and lactate bellow 19.6 mg/ dL. The proportion of normal CSF and normal CSF parameters were recorded. Results: 34,434 CSF samples from suspected CNS infection were included. Of those, 22,960 were classified as clear and colorless (66.7%). Among clear and colorless CSF samples 13,137 (57.2%) had normal CSF cytology and biochemical findings. The probability of CSF abnormalities in the cytological and/ or biochemical examination in clear and colorless CSF samples obtained from patients with suspected CNS infection was 42.8%. Discussion: In this study, we showed a high frequency of cytological and/or biochemical abnormalities in clear and colorless CSF obtained from patients with suspected CNS infection. Conclusions: Viral infections and other inflammatory CNS diseases are among the conditions that may present with clear and colorless CSF. Therefore, a clear and colorless CSF in suspected CNS infections has a little predictive value for CSF abnormalities.