Background: White matter changes are common finding during brain autopsies especially in elderly. Although there are many studies applying radiological-pathological correlation on these lesions, their pathogenesis is still unclear. However, a number of possible causes have been suggested including: hypoxic-ischemia, altered blood brain barrier permeability, vascular pathology and chronic hypoperfusion. As usually there is a multiplicity of causes in any individual case, it is very difficult to pinpoint the major causal factor contributing to observed pathological changes. In this study, we document the white matter pathology in global acute hypoxic/ischemic injury due to cardiac arrest as the major causal factor.

Method: We retrieve 16 cases of cardiac arrest encephalopathy in our archive with post arrest survival range from 6 hours to 14 days. Several special, and immunohistochemical stains were used to study the axonal and myelin pathology.

Result: The pathogenicity of the cardiac arrest was confirmed in all cases by demonstrating the expected gray matter pathology, albeit in varying degree of severity. The white matter changes range from unremarkable in the first 2 days, evidence of cerebral edema (visualized from 3rd day on), and early axonal degeneration, to diffuse myelin pallor secondary to marked axonal loss on day 14.

Conclusion: The white matter changes in post cardiac arrest are mainly due to early cerebral edema and axonal degeneration and the effect on myelin is secondary.