Using imaging to identify psychogenic parkinsonism before deep brain stimulation surgery. Report of 2 cases.

The frequency with which patients with atypical parkinsonism and advanced motor symptoms undergo deep brain stimulation (DBS) procedures is unknown. However, the potential exposure of these patients to unnecessary surgical risks makes their identification critical. As many as 15% of patients enrolled in recent early Parkinson disease (PD) trials have been found to lack evidence of a dopaminergic deficit following PET or SPECT imaging. This suggests that a number of patients with parkinsonism who are referred for DBS may not have idiopathic PD. The authors report on 2 patients with probable psychogenic parkinsonism who presented for DBS surgery. They found that both patients had normal caudate and putamen [(18)F]-fluorodopa uptake on PET imaging, along with normal expression of specific disease-related metabolic networks for PD and multiple system atrophy, a common form of atypical neurodegenerative parkinsonism. The clinical and PET findings in these patients highlight the role of functional imaging in assisting clinical decision making when the diagnosis is uncertain.