Gerstmann-Sträussler-Scheinker's disease. Electron-microscopic observations on a brain biopsy.

Light and electron microscopic observations are reported on a brain biopsy of a man of 59 with a rare familial disease of the CNS and a 5-year clinical course. Electron micrographs of the frontal biopsy reveal plaque-like deposits composed of amyloid cores, often multicentric in the cortex and subcortical white matter. They are localized between enlarged astrocytic processes. In the neuropil they are sometimes associated with abnormal neuritic processes, in the white matter with processes of fibrous astroglia and basement membranes. There are no signs of primary neuritic or synaptic involvement in the plaque formation which is more obviously associated with altered astrocytic processes. Moreover, degenerative alterations in the cortical vessels and slight astroglial spongiform changes as well as oligodendroglial proliferation can be found. Plaques are considered to be mainly of the kuru type; the relationship with transmissible spongiform encephalopathies is discussed.