The pH and the CO 2 Content of Cerebrospinal Fluid in Epilepsy. ∗

Abstract

Although considerable work has been done on the acid-base relationships in epilepsy, the evidence presented thus far has been conflicting and indecisive. Because of the importance of this phase of the problem, we have determined the pH and CO₂ content of the cerebrospinal fluid in 125 epileptics and 30 non-epileptic control subjects by procedures which eliminate errors due to loss of CO₂. 1 , 2

The colorimetric method of McQuarrie and Shohl 1 used for determining the pH may be briefly described as follows: The clear fluid is drawn into a special glass sampling burette over clean mercury after all air in the connecting tubes has been eliminated by means of a 3-way stop-cock. In preparation for taking the sample a number of tenths of a cc. of 0.0075% phenol red equal to the number of cc. of fluid to be taken is measured into the apparatus. After the spinal fluid is mixed with the dye in this concentration, it is read directly at 38°C. against the bicolor standards of Hastings and Sendroy in a simple comparator block made to hold the sampling burette and standard tubes which have the same diameter. By slightly elevating the mercury reservoir of the sampling tube and turning the stop-cock of the latter, spinal fluid is forced into an Oswald-Van Slyke pipette. This is then measured directly into the Van Slyke and Neil 2 apparatus under mineral oil for determination of the CO₂. In the calculation of the CO₂ allowance is made for the dilution of the spinal fluid by the dye solution.

Several facts suggest that the occurrence of epileptic attacks depends at least in part upon a disturbance in the mechanisms regulating acid-base equilibrium. Certain procedures, which are often effective in preventing seizures, such as fasting, 3 the use of strongly ketogenic diets, 4 , 5 and the administration of acid-forming salts or carbon dioxide, 6 tend to produce mild acidosis.