The automated cell counter Siemens ADVIA 2120i was used. For the reference range section, we analyzed CSF from 80 neurologically healthy volunteers. For the differential diagnosis section we analyzed cell counts and hospital records from 175 patients with CSF mononuclear pleocytosis.
Correlation was good between automated and manual leukocyte counts for samples with erythrocyte counts < 250 cells/渭L. For the neurologically healthy volunteers studied in the reference range section, the 95th percentile was 3.0 cells/渭L for lymphocytes, 1.0 cell/渭L for monocytes and 1.0 cell/渭L for granulocytes. In the differential diagnosis section, comparisons were done between the groups Lyme neuroborreliosis and viral CNS infection. There were no significant differences between these two groups regarding cell counts; neither for lymphocytes, median 58 cells/渭L vs. 72 cells/渭L (P = n.s.); nor for monocytes, median 13 cells/渭L vs. 16 cells/渭L (P = n.s.); nor for granulocytes, median 1 cell/渭L vs. 2 cells/渭L (P = n.s.)
We suggest new CSF cell count reference ranges of < 4 cells/渭L for lymphocytes, < 3 cells/渭L for monocytes and < 3 cells/渭L for granulocytes. The separation of mononuclear cells into lymphocytes and monocytes did not facilitate the discrimination between Lyme neuroborreliosis and viral CNS infection.