[Primary degeneration of the thalamus with dementia--2 cases with family background].

This is a report on two male patients aged 22 and 43 years, respectively, who developed a fatal progressive demential syndrome that lead to the death of one after 16 months and of the other patient after 25 months and that presented with the typical clinical pattern of "subcortical dementia". In both the cases, the hospital had suspected Creutzfeldt-Jacob's disease but this was not confirmed by microscopy of the tissue; the typical form of manifestation was absent. Instead, microscopy of the brain revealed a marked symmetric degeneration of the thalamus with special preference given to the anterior and media nuclear groups. Predilection for the neothalamic against the palaeothalamic and archithalamic structures produced a very strong impression of a system-related thalamic degeneration process of the type occasionally discussed on the basis of similar observations. Parallel to the atrophic process there were also degenerative changes that were less pronounced, in the rubro-olivo-cerebellar system and in one case a moderately pronounced involvement of the second motor neuron. Both observations of a "thalamic dementia" are discussed against the background of relevant literature published so far on the subject.