Walsh & Hoyt: Pathology

The neuropathology ofADEMis somewhat different from that of MS. Whereas the pathologic findings in MS are typically asymmetric, multifocal demyelinating plaques of variable size, ADEM is characterized pathologically by diffuse, symmetric perivenous inflammation and demyelination. On gross examination, petechial hemorrhages may be visible on the surface of the brain and spinal cord. Brain weight is often increased and correlates with the presence of edema and swelling of the gyri. Coronal section reveals substantial congestion of parenchymal blood vessels, particularly in the white matter. Rare patients have evidence of hydrocephalus caused by aqueductal stenosis related to ependymal damage from the inflammation.