The glial reaction in closed head injuries.

The development of the glial reaction in human closed head injury has been investigated using morphometry and statistical analysis. The brains of eight individuals that survived less than 48 h following closed head injury were analysed using immunoperoxidase for glial fibrillary acidic protein (GFAP). Controls were eight patients without neurological disease. The density of reactive astrocytes was estimated in 25 fields in each of 10 different areas sampled bilaterally avoiding the subpial and subependymal zones, and the perivascular white matter. There was great variation between the zones within and between groups, and considerable variation between individuals. The raw data were expressed as logarithms averaged and analysed using the median and non-parametric statistics. The corpus callosum in the head injury group showed the highest densities of reactive astrocytes, particularly in the splenium which achieved statistical significance using the non-parametric tests. This pattern was not reproduced in the control group. Although there was overlap between the head injured and control individuals, the head injury group had relatively higher densities in all zones, and showed an overall increase in the density of reactive astrocytes. This achieved statistical significance in the corpus callosum, the occipital subcortical white matter, and the cerebellum. This study has shown that the glial reaction is often prominent in the corpus callosum irrespective of the presence of a primary lesion although the pattern varies from case to case.