Subacute sclerosing leukoencephalitis: ultrastructure of intranuclear and intracytoplasmic inclusions.

Intranuclear inclusions found in glial cells of two cases of subacute sclerosing leukoencephalitis have been examined in the electron microscope. The inclusions are composed of filamentous tubules 170 to 230 angstroms in diameter, which bear a general resemblance to the intranuclear structures observed in cells infected with measles virus. This finding provides further suggestive evidence that a virus may be involved in the pathogenesis of subacute sclerosing leukoencephalitis.