The significance of perivascular infiltrations in multiple sclerosis.

143 autopsy cases of multiple sclerosis (19 acute and 124 chronic cases) were analysed histologically for the extent of active demyelination and the degree of infiltration within and outside the demyelinating lesions and in the leptomeninges. The results were compared with the duration of the illness. Infiltrations were found in 60% of all cases but more often (74%) in those with active demyelination. Inflammatory lesions outside demyelinating foci were observed in 27% of the total, and in 80% of them active demyelination was present. Inflammatory lesions in the meninges were present in 41% of the total and in 80% of these were accompanied by active demyelination. The duration of illness correlated with decreasing severity of active demyelination and of perivascular infiltration. Patients treated with cortico-steroids and/or immunosuppressive substances showed no or only moderate inflammatory lesions. The duration of illness in both these groups was significantly longer than the average of untreated patients. The significance of these pathological findings for the CSF cytology in multiple sclerosis is discussed.