While isolated data on electrolytes in postmortem cerebrospinal fluid have been reported (1,3,5), a systematic study of the principal ions has not been available. The present report gives analyses of 157 postmortem cerebrospinal fluids and includes values for cations, anions and pH.Materials and methods. The material consisted of 131 male bodies. average 57 years old, of white and colored race, autopsied on the average 10% hours after death. A second series was used for pH determinations only and consisted of 26 cases, 62 years average age, examined after an average 5% hour postmortem interval. To obtain data, which may be valid as "normals," cases were selected on the basis of pathological changes presumably unrelated to electrolyte metabolism. Cerebrospinal fluid was removed by cisternal puncture and, if free of gross contamination by blood or brain tissue, was used after centrifugation. The following analytical procedures were employed: flame photometry for sodium and potassium (4) ; Clark-Collip's method for calcium ( 2 ) ; Denis-Briggs' method for magnesium (2) ; Van Slyke-Hiller's modification of Sendroy's method for chlorides( 2). The COa values were previously published ( 5 ) and obtained by Van Slyke's gas volumetric method(2). Measurements of pH were performed at 375°C (within 60 min. after removal) with a Beckman pH meter and a blood electrode assembly provided with rubber cap, through which the spinal fluid was injected directly from syringe or after centrifugation under oil.Average and range of cations, anions and pH in postmortem cerebrospinal fluid 10;4 and 5% hours after death respec-
Results.tively are compiled in Table I and compared to corresponding antemortem values. It will be noted that there is a marked increase of potassium and inorganic phosphorus, a moderate increase of magnesium and a slight to moderate decrease of sodium, chlorides and HCOR after death, while calcium values approach closely those found during life. There is, however, more or less marked scattering of all values over wide ranges. The postmortem values of pH are considerably lower than antemortem figures.The acid-base equilibrium in postmortem cerebrospinal fluid as seen in Table I1 shows fair agreement of the total milliequivalents of cations with the antemortem figure due to the fact that the sodium deficit is compensated by the potassium increase. On the other hand, there is a large deficit of 24 milliequivalents of anions due to the decrease of chlorides and HCOn ions in postmortem cerebrospinal fluid and insufficient compensation by the increase of phosphorus. This result causes an apparent shift of the acid-base equilibrium to the side of base.Discussion. Mason, Klyne and Lennox ( 3 ) first observed the marked postmortem rise of cerebrospinal potassium, which however, failed to show close correlation with time after death except on a statistical basis. These findings were borne out by the present investigation, and here again a constant time relation was absent in regard to postmortem changes of sodium, chlorides a...
