Scott J. Sherman

Evaluation of Parkinsonian Syndromes (PS) with Ioflupane iodine-123 dopamine transporter single photon emission computed tomography (DaT-SPECT), in conjunction with history and clinical examination, aids in diagnosis. FDA-approved, semi-quantitative software, DaTQUANT^TM (GE Healthcare, Chicago, IL, USA) is available to assist in interpretation. This study aims to evaluate the optimal variables and thresholds of DaTQUANT to yield the optimal diagnostic accuracy. It is a retrospective review with three different patient populations. DaT-SPECT images from all three study groups were evaluated using DaTQUANT^TM software, and both single and multi-variable logistic regression were used to model PS status. The optimal models were chosen via accuracy, sensitivity, and specificity, then evaluated on the other study groups. Among single variable models, the posterior putamen yielded the highest accuracy (84% to 95%), while balancing sensitivity and specificity. Multi-variable models did not substantially improve the accuracy. When the optimal single variable models for each group were used to evaluate the remaining two groups, comparable results were achieved. In typical utilization of DaT-SPECT for differentiation between nigrostriatal degenerative disease (NSDD) and non-NSDD, the posterior putamen was the single variable that yielded the highest accuracy across three different patient populations. The posterior putamen’s recommended thresholds for DaTQUANT are SBR ≤ 1.0, z-score of ≤−1.8 and percent deviation ≤ −0.34.

The long-term safety of deep brain stimulation (DBS) is an important issue because new applications are being investigated for a variety of disorders. Studying instances where DBS was inadvertently implanted in patients without a movement disorder may provide information about the safety of the therapy. We report the case of a patient with a psychogenic movement disorder treated with deep brain stimulation (DBS). The patient presented at our clinic after 5 years of chronic DBS of the subthalamic nucleus (STN) for presumed Parkinson's disease. A dopamine transporter (DAT) scan (DaTscan) showed normal DAT distribution in the striatum. A positron emission tomography (PET) scan showed no abnormal metabolic patterns. Further psychiatric and neurological evaluations revealed that the patient was suffering from a psychogenic movement disorder. The patient displayed no sign or symptom from the stimulation, and DBS did not lead to any benefits or side effects for this patient. We argue that the absence of side effects, the normal DaTscan, and PET scan after 5 years of chronic stimulation illustrate the safety of DBS on neural tissue.