Neuropathological Aspects

Abstract

Many of the diseases affecting the basal ganglia including the SN and VTA are classified as primary neuronal degenerations, i.e., diseases in which, for unknown reasons, neurons of a particular type or in a particular region successively shrivel or die (Oppenheimer 1984). These degenerative diseases are characterized by: selectivity, affecting one or more systems of neurons in a more or less symmetrical pattern; steady progression; and variability in their clinical and pathological features. In many neurodegenerative conditions there is an appearance of ‘linked’ or ‘chain’, i.e., transneuronal, degeneration (Oppenheimer 1984; Hardy et al. 1986; Saper et al. 1987). Examples are the ‘linked’ degeneration of the globus pallidus and subthalamic nucleus in progressive supranuclear palsy and that of the neostriatum and SN in multiple system atrophy.