Pontine axonal injury after brain trauma and nontraumatic hypoxic-ischemic brain damage

Int J Legal Med. 1999;112(4):261-7. doi: 10.1007/s004140050246.

Abstract

Experimental studies have shown that diffuse axonal injury is usually induced by positive or negative acceleration mechanisms. In order to determine the reliability of axonal injury (AI) as a marker of this type of traumatic insult, we compared cases of trauma-induced focal cortical hemorrhage without dural involvement (n = 67) with cases of trauma-induced subdural bleeding without cortical hemorrhage (n = 26). Both groups exhibited a wide range of post-traumatic survival times. The injuries in the first group were caused mainly by direct impact to the head, those in the second by acceleration/deceleration mechanisms. The investigations were based primarily on immunohistochemical demonstration of antibodies targeted to beta-amyloid precursor protein (beta-APP) in the pons as a marker of AI and the results were assessed semiquantitatively. No significant differences were found between the two groups. In both groups AI was detected in 80-100% of cases with survival times of more than 3 h and two thirds of all positive cases showed pronounced positivity. Additional comparison of cases of brain death due to mechanical trauma (n = 14) with cases of brain death due to non-mechanical trauma (n = 18) also disclosed no significant intergroup differences. Finally, investigations of the pons in cases of non-traumatic death due to cerebral hypoxia/ischemia (n = 51) demonstrated AI with the same frequency as in the other groups, although the expression tended to be less pronounced. Our results confirm that beta-APP expression in the pons is a reliable indicator of AI but does not discriminate between injuries caused by traumatic strain or shearing mechanisms and secondary damage due to cerebral hypoxia/ischemia or edema. In the large majority of cases with prolonged post-traumatic survival, it can therefore be assumed that AI in the pons is the consequence of primary and/or secondary events or a combination of both, as is common in non-missile head injury survived for more than 90-120 min. Therefore, positive differentiation of the type of biomechanical event based on this criterion alone is not possible.

MeSH terms

  • Adolescent
  • Adult
  • Amyloid beta-Protein Precursor / analysis
  • Axons / pathology*
  • Biomechanical Phenomena
  • Brain Damage, Chronic / pathology*
  • Brain Death / pathology
  • Brain Injuries / pathology*
  • Cerebral Hemorrhage / pathology
  • Child
  • Child, Preschool
  • Female
  • Head Injuries, Closed / pathology*
  • Hematoma, Subdural / pathology
  • Humans
  • Hypoxia, Brain / pathology*
  • Infant
  • Male
  • Middle Aged
  • Pons / injuries*
  • Pons / pathology
  • Postmortem Changes
  • Retrograde Degeneration / pathology

Substances

  • Amyloid beta-Protein Precursor