Necrotic changes of the spinal cord with immune-complex-mediated disseminated vasculitis in a case of atypical allergic encephalomyelitis.

A 42-year-old woman demonstrated recurrent, progressive neurological symptoms of peripheral and central nervous system damage of undefined infectious origin. Laboratory investigations showed abnormalities in the CSF and serum, suggesting subacute viral infection. Neuropathological examination revealed complete, widespread necrosis in the cervical and thoracic segments of the spinal cord with mononuclear and microglial infiltrations. There was pronounced thickening and fibrinoid necrosis of the vessel walls with mononuclear cuffs along the spinal cord. Dispersed, similar but less intensive inflammatory changes were present in the medulla oblongata, midbrain and basal ganglia. Surprisingly, there was diffuse demyelination with only slight glial and inflammatory reactions throughout the white matter of both hemispheres. The finding of coarse- and fine-grained deposits of IgG and C3 component of complement in the vessel walls of the spinal cord and vasa nervorum of cervical roots and peripheral spinal nerves, together with positive heterologous complement binding and the results of glycine-HC1 buffer elution, suggested immune-complex-mediated disseminated vasculomyelinopathy of the CNS and PNS. Consequent local ischemic changes and hypersensitivity phenomena led to frank necrosis of the cervical spinal cord and to extreme white matter demyelination in the brain. The case was diagnosed as allergic encephalomyelitis in which diffuse demyelination occurred coincidentally with spinal cord necrosis.