Walsh & Hoyt: Pathology

The brain, optic nerves, and spinal cord of patients with neuromyelitis optica are affected by scattered lesions of demyelination that principally affect the white matter but also may affect the gray matter. In some cases, the cerebral cortex is only slightly affected or completely spared; however, the optic nerves and the spinal cord are invariably damaged. Both optic nerves are almost always affected, although the degree of demyelination may be symmetric or asymmetric. The spinal cord is affected extensively in all cases of neuromyelitis optica. Liquifaction, necrosis, and formation of cavities are common. There is widespread destruction of myelin sheaths, and axis cylinders may also be destroyed. There may be small areas of perivascular lymphocytosis in both brain and spinal cord. Formation of glial tissue occurs in mild or moderately severe cases; however, it is not present or is minimal in fulminating, rapidly fatal cases.