Abstract
In a recent report on the clinical and pathological features of Guamanian ALS/PD and post-encephalitic parkinsonism/ALS a number of similarities were described, notably in the distribution of neurofibrillary tangles throughout the nervous system. In this account additional pathological features which these disorders share (and which differ from classical ALS, Parkinson's and Alzheimer's diseases) are described. These include atrophy of the globus pallidus and the entire substantia nigra, viz. pars compacta and pars reticulata. Moreover, neither Lewy bodies nor senile plaques are features of the Guamanian and post-encephalitic disorders. The significance of these observations and their relationship, more generally, to parkinsonism, ALS and dementia are discussed.