Excessive dopamine neuron loss in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) and Parkin- son's disease (PD) differ in their response to dopaminergic replacement therapies, despite having a similar degree of neuronal degeneration in the dopaminergic substantia nigra. We observed more widespread dopamine neuron loss in the extranigral A10 midbrain cell groups in PSP com- pared with PD. These cell groups innervate subcortical and cortical regions and may be required for adequate response to levodopa therapy. © 2007 Movement Disorder Society