Shaken infant syndrome: developmental neuropathology, progressive cortical dysplasia, and epilepsy.

This study describes the developmental neuropathology of two infants who survived 7 and 9 years, respectively, an episode of violent shaking (shaken infant syndrome) early in their lives. The shaking injuries include cortical and subcortical contusions, hemorrhages, hypoxic/ischemic and axonal damage, and severe edema. The types, distribution, and resolution of these shaking injuries are detailed by sequential radiographic studies and by pathologic examination at postmortem. Despite their severity and extent, these injuries resolved in a relatively short period of time. By 6 months, the original injuries are repaired and the resultant encephaloclastic encephalopathies (e.g., multicystic encephalomalacia, porencephaly, generalized white matter attenuation, diffuse cortical atrophy, microgyria, ulegyria, and hydrocephalus ex vacuo) are well established. No appreciable pathologic differences are detected when radiographic findings at 6 months of age are compared to postmortem observations. On the other hand, undamaged and/or partially damaged cortical regions survive the original insult and undergo post-injury reorganization that transforms the residual cortex structural and presumably functional organization. Prominent features of this post-injury reorganization include progressive cortical dysplasia with cytoarchitectural disorganization, laminar obliteration, morphologic and functional (synaptic reorganization) transformation of some neurons, preservation of layer 1 intrinsic fibers and Cajal-Retzius cells, and the presence of large (hypertrophic) intrinsic neurons with intense neurofilament immunoreactivity. We propose that this progressive dysplastic process modifies the residual cortex structural and functional organization, influences the child's neurological and psychological maturation, and may play a significant role in the pathogenesis of ensuing neurological and/or psychological sequelae.