[The "natural history" of bacterial meningitis in the interpretation of cerebrospinal fluid parameters (author's transl)].

The "natural history" of bacterial meningitis, although today a hypothetical event, must be essential reference to interpret the various cerebro-spinal fluid parameters, either in diagnosis or in monitoring. The Authors give first a synopsis of the normal cerebro-spinal fluid. They divide the natural history of bacterial meningitis into five stages, describing the variations in the main parameters (macroscopical, bacteriological, humoral and cytological). The Authors point out also the new bacteriological pathology of leptomeningitis arising from inadeguate therapy: 1) a flare-up of meningitis of form L and 2) bacterial meningitis of "decapitate" type. In 2) the Authors stress the importance in the laboratory of differential diagnosis from aseptic or viral meningitis.