Correlation of cerebellar granular layer autolysis with ante-mortem systemic acid-base status

Research in neuroscience relies heavily upon postmortem human brain tissue. Cerebellar granular layer autolysis (GLA) is a surrogate marker for the quality of such tissue and suitability for molecular analysis. GLA is associated with reduced brain tissue pH. The aim of this study was to assess correlation of GLA with premortem systemic acid-base status. This is a retrospective study in which 62 consecutive adult autopsy cases were included. Sections of cerebellum were reviewed microscopically for presence of GLA. Autolysis was graded as negative, grade 1, grade 2, and grade 3. Medical records were reviewed for arterial blood gas analysis. Postmortem interval was recorded. 23 of 62 cases showed GLA. Of the 23 patients with autolysis, 22 were acidotic and 1 was alkalotic. Of these 23 cases, 15 had metabolic acidosis, 4 had respiratory acidosis, 3 had combined acidosis and 1 had respiratory alkalosis. There was no statistically significant difference in postmortem interval between the two groups. 10 cases with grade 3 autolysis had mean pH of 7.13, 7 cases with grade 2 autolysis had mean pH of 7.23 and in 6 cases with grade 1 autolysis the mean pH was 7.2. Overall, the mean pH in patients with GLA was 7.19, and in the non-autolytic cases the mean pH was 7.28 (P < 0.05). There was no correlation between the degree of acidosis and severity of autolysis. GLA is associated with premortem systemic acidosis, and premortem systemic alkalosis is associated with the absence of GLA. Premortem acid-base status may serve as an additional quality indicator for assessment of tissue for research.