9. Test for total acidity and relative acidity.
10. Cholin may be tested for.
In the serous form one will find the cells increased somewhat, especially the leucocytes, but the micro-organisms are conspicuous by their absence.
The Lange (colloidal-goldchloride) test will show the characteristic color reaction of a septic process.
The Noguchi (butyric-acid) test will be positive. Excess of albumin.
The Wassermann, Nonne and Noguchi tests for syphilis are negative. (Unless such a case should be a complicated one.)
The test for sugar is very important in that in serous meningitis sugar is present.
The relative acidity is not markedly affected, and cholin is not present, or, if so, in only small quantity.
(b) Septic meningitis.—If this is localized, and there is a collateral serous meningitis associated with it, then the symptoms may be the same, as just described; however, the cerebrospinal fluid will show a greater degree of irritation, and the fluid may contain some micro-organisms. The majority of localized septic meningitis cases, however, are not as severe in their course as the serous or diffuse septic forms. The one important symptom is the localized headache, which is quite persistent, and the greater rise in the temperature. There are, undoubtedly, many cases of localized meningitis that show a perfectly normal cerebrospinal fluid, and most of the cardinal symptoms absent; and these are the cases that usually get well or lead to extradural abscesses subsequently.
The diffuse septic meningitis is the most discouraging intracranial complication that we have to deal with, and the diagnosis as a rule is not difficult. It usually is preceded by the serous form, but within a very short time develops the graver symptoms of sepsis. The most positive symptom is the spinal puncture. The fluid comes out under pressure, but not so great as in the serous form, and is turbid. The turbidity varies in degree with the amount of infection. It has the appearance at times of pure pus; in fact, that is what it is. Bacteriologically one will find many micro-organisms of the character of the infection; and leucocytes or pus cells are very numerous.