Degenerative parkinsonism in patients with psychogenic parkinsonism: A dopamine transporter imaging study

To evaluate patients with "clinically established" psychogenic parkinsonism (PsyP) using single-photon emission computer tomography (SPECT) with the technetium-99m labeled tracer TRODAT-1, a dopamine transporter (DAT) ligand, and investigate whether these patients have an underlying degenerative parkinsonism.

Five patients with PsyP were assessed using demographic data, standard clinical scales for Parkinson's Disease (PD), and a neuropsychiatric interview. DAT imaging using SPECT with TRODAT-1 was performed, and values for caudate/putamen DAT binding potentials (BP) registered. Patients with PsyP were matched with PD (n=5) and healthy control subjects (n=5).

The mean age (years-old) at first evaluation in the PsyP group was 37.4+/-3.7, and the mean disease duration (years) was 3.9+/-1.2. DAT BPs (means+/-standard deviations) on right/left caudate were, respectively, 0.69+/-0.18 and 0.70+/-0.18 in the PD group versus 1.17+/-0.06 and 1.12+/-0.10 in the control group. DAT BPs on right/left putamen were, respectively, 0.48+/-0.10 and 0.45+/-0.06 in the PD group versus 1.10+/-0.10 and 1.21+/-0.43 in the control group. Two out of five patients from the PsyP group had values for DAT BP in the putamen under the cut-off (< or =0.70) for controls, implying pre-synaptic dopaminergic deficit.

Our data in this small group of patients suggest that DAT imaging is a tool that may help in the identification of underlying degenerative parkinsonism in PsyP.