CYTODIAGNOSIS AND SPINAL FLUID EXAMINATIONS 425 



bacilli. This process does not seem to have met with much favor in this country. 

 (Using sodium citrate obviates the necessity for digesting the coagulum.) 

 The same points will hold for ascitic fluid as for pleural fluid. 



CEREBROSPINAL FLUID EXAMINATIONS 



In taking cerebrospinal fluid for culture and cytodiagnosis we use a 

 stout antitoxin needle without attaching a syringe. Aspiration is 

 responsible for many of the ill effects of lumbar puncture. 



The needle should be about 4 inches long for an adult. Sterilize the skin and needle 

 as described for blood cultures from a vein. To make a lumbar puncture, place 

 patient on left side with knees drawn up. A line at the level of the iliac crests passes 

 between the third and fourth lumbar vertebrae. Select a point midway between the 

 spinous processes of these lumbar vertebrae and enter the needle two-fifths of an 

 inch to the right of this point, pushing the needle inward and upward. Collect 

 the material in a sterile test-tube. Make cultures on blood-serum and then cen- 

 trifugalize and examine the sediment as for pleural fluids. 



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 cerebrospinal 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 cerebrospinal fluid is then sucked up to n. 

 After mixing, the cell count is made with the haemocytometer. Nor- 

 mally we have only one or two cells per cubic millimenter, but in tabes 

 or general paresis this is increased to 50 or 100 cells (greatest at onset of 

 disease). 



It is advisable to make the cell count of the fluid as soon after obtaining it as 

 possible, the cells tending to degenerate. It is customary to consider fluid contain- 

 ing blood as unsatisfactory for the cell count as well as for the globulin tests, but one 

 can calculate the leukocytes due to blood content by counting the red cells and sub- 

 tracting one leukocyte for each 750 red cells. 



It is now generally recommended to make the spinal puncture with the patient 

 seated on a stool with the shoulders inclined forward thus giving the greatest space 

 between the spinous processes. After the punpture the patient should drink a 

 glass or so of water and remain in bed for a day. In some clinics the subjects lie 

 down for a few hours and then return to their homes. 



In general terms it may be stated that: 



1. A lymphocytosis indicates a tuberculous or poliomyelitis process. 



2. An abundance of polymorphonuclear and eosinophilic leukocytes 

 indicates a meningococcic, streptococcic, influenza or pneumococcic 

 infection. The fluid in (i) tends to be clear, that in (2) cloudy. 



