Thalamus degeneration in Japan. A review from clinical and pathological viewpoints.

12 Japanese cases with marked thalamus degeneration are reviewed. They are divided into 3 groups. The 4 cases of the first group showed a relatively short clinical course. Neuropathologically, the lesions of this group are selectively severe in the thalamus, and olivocerebellar atrophy is also observed. Because of the significance of the thalamic changes, this group is called 'primary thalamus degeneration'. The cases of combined system degeneration and presenile dementia, such as Pick's disease, are described in the 2nd and 3rd groups. In the thalamus, the developmentally younger, and medially and dorsolaterally located nuclei are most severely affected in all the cases. The substantia nigra, globus pallidus and cerebellar afferent systems, and occasionally the dentate nucleus, subthalamic nucleus and reticular formation, are also involved. In the cases of presenile dementia, in which the frontal and posterior parietal lobes are damaged, degenerated areas in the cerebrum and thalamus have a close relationship with each other genetically as well as in fiber connections. The clinicopathological relationship is discussed on the basis of those neuropathological findings.