Biochemical changes in cerebrospinal fluid after death

Biochemical changes in various body fluids after death have been investigated before in various countries. They were found to be useful in a variety of situations. They may aid in finding the cause of death when autopsy is negative or not available and in estimation of the time since death. To asses the biochemical changes in cerebrospinal fluid after death as well as to asses these changes in relation to different postmortem intervals in order to estimate the time since death. A total of forty autopsy cases were selected randomly for the study at the medicolegal institute in Baghdad. Time of death was obtained from police reports, close relatives and case sheets for those admitted to hospitals. CSF was aspirated from the brain and centrifugation was done immediately. The supernatant was collected; determinations of glucose, protein, sodium, potassium and urea were done at Kadhmiya Teaching Hospital. There was an increase in potassium level in CSF with increasing postmortem interval and a significant correlation was found between them [p<0.001]. A slight to moderate reduction in sodium level in CSF and no correlation was found with postmortem interval. Glucose was decreasing with increasing postmortem interval and a significant correlation was found between the two parameters [p < 0.001]. Proteins levels were higher than their normal ante mortem value in CSF and no correlation was found with postmortem interval. Urea was a relatively stable parameter. The study revealed a significant correlation between potassium and glucose concentrations in CSF with postmortem interval aiding in estimation of time since death with other means, while there were no correlation between sodium, urea and protein with postmortem interval. Urea was a stable biochemical marker reflecting its ante mortem level

Diagnóstico precoce da morte cerebral através do exame do líquido cefalorraquidiano: estudo em pacientes críticos com especial referência ao comportamento dos íons potássio e magnésio após a morte

O comportamento dos níveis liquóricos dos íons potássio e magnésio foi estudado prospectivamente em quatro pacientes comatosos com extensas lesöes do SNC e em quatro pacientes com morte cerebral diagnosticada nas últimas 24 horas e confirmada por EEC isoelétrico. Nos pacientes comatosos, os resultados foram K(mEq/l) - 2,4; 2,7; 2,7; 2,8 (média 2,65); Mg (mg/dl) - 2,6; 2,6; 2,4; 2,48 (média 2,52). Estes achados reafirmam a grande estabilidade das concentraçöes liquóricas de k e Mg no homem, mesmo após grave dano ao SNC. Houve uma grande variabilidade dos níveis de cátions encontrados logo após a morte cerebral. Em apenas um caso o diagnóstico näo foi seguido de aumento significativo do teor de K no LCR (2, 2; 3,1; 3, 4; 6,5 - 3,8 mEq/1). Os níveis de Mg näo demonstraram tendência clara a elevaçäo, mas os valores encontrados tenderam a dispersäo ampla (2,8; 2,8; 18; 1,6 - média 2,25 mg/dl). A integridade cerebral parece depender do controle estrito dos níveis de K e Mg no LCR. O achado de valores fora destes limites em um pacientes comatoso preenchendo critérios clínicos de morte cerebral poderia permitir seu diagnóstico precoce. Esta sugestäo exige, porém, maior número de doentes, incluindo condiçöes complicadoras, como choque, intoxicaçöes exógenas e hipotermia. O risco da punçäo espinhal neste contexto também exige investigaçäo. O achado ocasional de níveis normais de K e de valores muito variáveis de Mg sugere a persistência de mecanismos de captaçäo celular ativa dos íons, possivelmente de origem medular