CBS and Parkinson disease: The most consistent difference in metabolic activity between atypical parkinsonism and PD is decreased striatal glucose metabolism in atypical parkinsonism patients [30, 32, 35, 42, 47, 56, 68, 72], which is in agreement with post-mortem studies showing post-synaptic striatal neuronal loss in MSA, PSP, and CBS, but not in PD [73].