Counting cells in cerebrospinal fluid collected directly on membrane filters.

Accurate enumeration of cells in the cerebrospinal fluid is not feasible with the current method of counting cells in the Fuchs Rosenthal or Neubauer chamber when the count is near normal since the volume of fluid examined is too small. A sample of adequate volume to permit such accurate assessment may be collected from the lumbar puncture needle into a syringe through a ruled membrane filter in a Swinney cartridge. A study of 291 samples shows that the upper limit of the normal cerebrospinal fluid count is 2000 cells/ml (2/cmm) and not 5000/ml (5/cmm) as is currently accepted.