Laboratory Diagnosis in Neurology by Brigitte Wildemann Patrick Oschmann Hansotto Reiber

Author:Brigitte Wildemann, Patrick Oschmann, Hansotto Reiber
Language: eng
Format: epub, pdf
Publisher: Thieme Stuttgart New York
Published: 2010-12-08T16:00:00+00:00

Laboratory diagnosis is by direct microscopic detection of the pathogen in CSF using India ink preparations (Fig. 10.1). The yeast fungus must be distinguished from erythrocytes, granulocytes, and sebum. The fungus measures 4–6 μm and has a polysaccharide capsule of 1–30 μm. The India ink preparation is positive in 60–70% of non-AIDS patients with cryptococci, and in more than 90% of AIDS patients with cryptococci. If the findings are unclear or negative, detection by culture is still the gold standard. Detection of cryptococcal antigen using the latex agglutination test is also diagnostic. In non-AIDS patients, the CSF titer is below 1:1000; in AIDS patients it is above 1:1000. Sensitivity is lower for serum. Repeated testing increases the diagnostic value of the findings. In patients with CNS cryptococcomas, pathogen detection in the CSF is mostly negative. Antibody detection is of limited diagnostic value because these antibodies also occur in healthy persons. Cell counts may be normal or slightly increased, up to 300 cells/μL. Cytology shows a mixed-cell pattern dominated by lymphocytes, or only lymphocytes and plasma cells; total protein may be markedly increased up to 2500 mg/L. The immunoglobulin responses may be of the two-class or three-class type. Lactate levels of up to 13 mmol/L have been reported.

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