Brain flow changes before and after deep brain stimulation of the subthalamic nucleus in Parkinson's disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) markedly improves motor symptoms and reduces medication needs in Parkinson's disease (PD) patients. However, its effect on brain function has remained unclear. We used SPECT and the tracer ECD to measure regional cerebral blood flow before and 6 months after DBS of the STN in 22 PD patients and 13 healthy controls. PD patients were divided into good and poor responders to DBS, if changes in "off" UPDRS motor scores after surgery were >60% or <40%, respectively. Statistical analysis was performed using the SPM99 software. At baseline, all PD patients showed significant perfusion reductions in cortical areas (premotor frontal, parietal, and occipital). After DBS, changes were normalized only in the good responders, while cortical defects in the poor responders were unchanged. No flow decrements were detected in basal ganglia and thalamus in both groups, suggesting that DBS does not have a "lesion-like" effect. We conclude that good surgery outcome is associated with normalization of cortical flow abnormalities in PD.