Using imaging to identify psychogenic parkinsonism before deep brain stimulation surgery

Report of 2 cases

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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 [18F]-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.

Abbreviations used in this paper: DBS = deep brain stimulation; MSA = multiple systemic atrophy; MSARP = MSA-related spatial covariance pattern; PD = Parkinson disease; PDRP = PD-related metabolic spatial covariance pattern; SPM = statistical parametric mapping; UPDRS = Unified Parkinson's Disease Rating Scale.

Article Information

Address correspondence to: Michael Pourfar, M.D., 865 Northern Boulevard, Suite 201, Great Neck, New York 11021. email:

Please include this information when citing this paper: published online November 11, 2011; DOI: 10.3171/2011.10.JNS11554.

© AANS, except where prohibited by US copyright law.



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    Fluorodopa (FDOPA; A and B) and FDG (C and D) PET scans obtained in Case 1 (left) and Case 2 (right). Quantitative PET measurements from both scans were normal in the 2 cases.

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    A: Single-case SPMs of the FDG-PET scans obtained in Cases 1 and 2 compared with those obtained in healthy individuals. The patient in Case 1 exhibited increases in metabolic activity in motor cortical regions. Increases in metabolic activity in the cerebellar vermis are evident in both cases without accompanying changes in the basal ganglia. A representative single-case SPM obtained in a patient with classic symptoms of PD (age 43.5 years, disease duration 8 years) is presented for comparison. Metabolic increases (red voxels) are displayed at p < 0.05 (uncorrected) and overlaid on a standard MR imaging template. GP = globus pallidus. B: Network scores quantifying the expression of the disease-related metabolic patterns for PD (PDRP; top) and MSA (MSARP; bottom) are measured for the patients in Cases 1 and 2 (Patients 1 and 2; squares). These network values are compared with analogous measures from 25 patients with PD (triangles), 23 patients with MSA (diamonds), and 25 healthy volunteers (circles). Subject scores for both patterns are normal for our 2 patients. Error bars represent the mean ± SD for the PD, MSA, and healthy control groups. The horizontal broken line represents 2 SDs above the normal mean for each pattern. PDRP and MSARP subject scores for the patient with PD depicted in panel A are delineated by the short arrows.

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    Flow diagram illustrating clinical and imaging considerations when determining patient suitability for DBS surgery for medication refractory parkinsonism. LD = levodopa.


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