THE DIAGNOSIS OF DIFFUSE AXONAL INJURY - IMPLICATIONS FOR FORENSIC PRACTICE

The diagnosis of diffuse axonal injury (DAI), which may be of consider able importance in forensic medicine, necessitates widespread sampling of the brain for histology, Because a limited sampling method for scr eening brains for axonal damage would be of value for medico-legal wor k, the authors have tested the findings of an earlier study which sugg ested that a standard set of three blocks from above and below the ten torium could reliably be used in routine practice as a basis for the d iagnosis of DAI, A series of 22 previously diagnosed cases of DAI, wit h a range of survival times, was studied using immunohistochemistry wi th antibodies to beta-amyloid precursor protein (beta APP), the microg lial-associated antigen CD68 (PG-MI) and for GFAP. Strict histological criteria were used to assess traumatic damage, and the evolution of t he histological changes with increasing survival is described, In four cases, the sampling scheme employed yielded evidence of axonal damage in only one block, and a diagnosis of DAI could have been made in onl y 13/22 cases, In six of the shortest surviving cases, beta APP positi vity in the corpus callosum and brainstem outlined areas of early isch aemia, as well as of traumatic damage, so that interpretation of immun olabelling was not always clear-cut. The findings suggest that DAI can not be reliably diagnosed on a restricted number of blocks from vulner able areas, and that the use of beta APP and PG-M1 immunocytochemistry may bring interpretative problems that can only be resolved by taking a larger series of tissue samples for histology.