1. A lymphocytosis indicates a tuberculous or poliomyelitis process. With these diseases, the fluid will probably be clear.
2. An abundance of polymorphonuclear and eosinophilic leucocytes indicates an infection with pyogenic organisms, in which cloudy fluid is the rule.
Meningism shows very few cells.
Trypanosomiasis gives a cellular increase very similar to syphilis. In the work of the French Sleeping Sickness Commission five cells per cubic millimeter was taken as normal.
Not only may trypanosomes be found in the spinal fluid, when they mark the setting in of the “sleeping sickness” stage of trypanosomiasis, but a case has been reported of the presence of Trichinella embryos in the spinal fluid. Recently a few cases have been reported of anthrax meningitis, in which anthrax bacilli have been found in the spinal fluid.
Cell Count.—A method of examination considered by neurologists as of differential diagnostic value is to count the number of cells in a cubic millimeter of the cerebro-spinal fluid. The technic is to use a gentian-violet-tinged 3% solution of acetic acid. This is drawn up to the mark 0.5, and the cerebro-spinal fluid is then sucked up to 11. After mixing, the cell count is made with the haemacytometer.
Count all the cells appearing in the entire ruled area (9 large squares) and add one-sixth of this number to find the approximate total number of cells per cubic millimeter of spinal fluid examined as above. It is advisable to make the cell count of the fluid as soon after obtaining it as possible, the cells tending to degenerate or adhere to the glass of the tube. The latter can be minimized by vigorous shaking before withdrawal of the fluid for counting. Normally we have only two to ten cells per cubic millimeter, but in tabes and general paresis this is increased to 50 or 100 cells, greatest at onset of disease.
Pleocytosis.—Miller gives the following table as to pleocytosis:—
Average Incidence of Lymphocytosis in the Spinal Fluid
(Plaut, Relim and Schottmuller)