Quantitative evaluation of intranuclear inclusions in SSPE: correlation with disease duration.

Three types of intranuclear inclusions in neurones, oligodendrocytes and astrocytes were quantitatively evaluated by electron microscopy in the autopsy material derived from six cases of subacute sclerosing panencephalitis (SSPE) with different duration of disease. Viral nucleocapsids were found in neurones and oligodendrocytes with the highest incidence (about 38% of nuclei) in two acute cases (adolescent), whereas in two subacute cases only 10% of nuclei of these cells contained nucleocapsids. However, in one acute case (child) and one chronic case, no nucleocapsids were detected at all, despite very intensive study. Two other types of intranuclear inclusions--nuclear bodies (NBs) and granulofilamentous inclusions (GFs) were present in astrocytic nuclei in all cases. Nuclear bodies were found the most frequently (about 66%) in cases of a several-week-long duration, and their incidence decreased with the extended duration of the disease. In the case of a seven-year-long duration, about 31% of nuclei contained NBs. The incidence of certain types of NBs varied also in individual groups of cases, and the same applied to the occurrence of cellular nuclei with different numbers of NBs. Nuclear bodies types IVand V occurred with similar frequency, regardless of the disease duration. The highest incidence of nucleocapsids and NBs was accompanied by the highest (about 25%) frequency of GF in astrocytic nuclei. The incidence of the latter declined with the prolonged duration of the disease, and in the chronic case it was about 16 times lower than in acute cases. In some acute and subacute cases, GF occurred together with NBs. Astrocytic nuclei with both types of inclusions occurred with a similar frequency (about 1.6-1.8%).