Teaching NeuroImages: Drug-induced parkinsonism with asymmetrical putaminal DaT binding

A 64-year-old patient developed shuffling gait and postural instability over 8 months, in parallel to risperidone intake. Examination showed symmetric parkinsonian syndrome and mild left hemiparesis with spasticity, related to right middle cerebral artery stroke 10 years before. Within 1 month of risperdone withdrawal, parkinsonism disappeared, confirming drug-induced etiology. While degenerative parkinsonism is associated with reduction in striatal dopamine transporters binding in absence of structural lesions to basal ganglia, binding in drug-induced parkinsonism is normal.1 In our case, SPECT anomaly was incidental, related to the ischemic sequela (figure).2 This case highlights the importance of brain structural integrity for SPECT interpretation.