[Predictive value of the study of cerebro-spinal fluid in neurological diseases. Discriminant analysis of 733 cases].
INTRODUCTION: The study of cerebrospinal fluid (CSF) gives very valuable data for the diagnosis of certain neurological disorders. Objective. To discover the discriminative value of different tests and their usefulness in the study of neurological disorders. MATERIAL AND METHODS: Discriminative multivariate analysis was used for the group of parameters obtained from study of CSF and serum in a sample of 733 patients. BO was included, CSF cytobiochemical data and five of the equations used for calculation of the synthesis of intrathecal IgG. RESULTS: The best discriminative function was expressed as the intrathecal IgG with normal BHE. The formula of Tourtellotte was noteworthy for overestimation of the synthesis of intrathecal IgG when the albumin index indicated BHE rupture. Prospective reclassification of the 733 cases showed that these tests are well worthwhile to rule out immunologically mediated disorders (93% of the cases were correctly reclassified); they suggest the diagnosis in multiple sclerosis (66% correctly reclassified) and give very poor reliability when trying to distinguish between inflammatory infectious processes. CONCLUSIONS: In spite of their undoubted use in supporting the clinical diagnosis, the tests used for study of the synthesis of IgG, even complemented by cytobiochemical examination of the CSF, are not in themselves sufficient for use as a discriminative test in the differential diagnosis of neurological processes.