Critical evaluation of postmortem changes in human autopsy cisternal fluid. Enzymes, electrolytes, acid-base balance, glucose and glycolysis, free amino acids and ammonia. Correlation to total brain ischemia.

By studying early postmortem changes in cerebrospinal fluid (CSF) it is possible to draw conclusions as to premortem focal brain cell injury and terminal brain ischemia. Cisternal fluid (CF) from 40 different adult cadavers with no known neurological disorder was analyzed and compared with known in vivo values. They were divided into four groups (n = 10 in each group), CF samples taken 2, 4, 10, and 24 h after death. The enzyme activity of CK and CK-BB (EC 2.7.3.2) increased linearly and statistically significantly 4-24 h postmortem (P < 0.001) the 2 h values being already 10 to 20 times higher than in vivo, LD and its isoenzymes 1 to 3 (EC 1.1.1.27) distinctly 10 to 24 h after death. Glucose and pyruvate concentrations in the CF declined, as did Na+ and Cl-. Lactate and K+ increased over time. The earliest statistically significant changes between different timepoints were seen in lactate, pyruvate and K+ concentrations. The GABA concentration was already more than 170 times at 2 h postmortem, and glutamate more than 20 times higher than in vivo. The concentrations of alanine, glycine, lysine, histidine, isoleucine, phenylalanine, and tyrosine were 2 to 3 times higher at 2 h postmortem than during life. The concentrations of all amino acids and ammonia increased linearly and statistically significantly (P < 0.001) in the CF 4 to 24 h postmortem.