PET imaging of disease progression in Parkinson's disease with deep brain stimulation of the subthalamic nucleus

Recently, neurosurgical interventions experienced a renaissance in the treatment of motor complications in advanced PD. In particular, deep brain stimulation of the subthalamic nucleus (STN-DBS) has become a highly effective neurosurgical treatment option. Hyper-active STN neurons occuring as a result of striatal dopamine depletion in PD exert a strong glutamatergic outflow on their projection sites, such as the dopaminergic neurons of the substantia nigra. Therefore, some authors proposed neuroprotective properties of STN over-activity blockade by the DBS technique. In order to investigate this hypothesis, our groups performed a prospective serial 18-Fluorodopa (FDOPA) PET study which determinated disease progression during the first years after STN-DBS implantation in 30 patients with advanced PD patients. FDOPA PET has been proven as a reliable measure of PD progression. Dependent on the PET data analysis approach, annual progression rates relative to baseline were 9.5 to 12.4% in the caudate and 10.7 to 12.9% in the putamen. This is the first functional imaging study demonstrating a continuous decline of dopaminergic function in advanced PD patients under clinically effective bilateral STN stimulation. The progression rates in patients with STN-DBS are within the range of previously reported data from longitudinal imaging studies in PD. Therefore, neuroprotective properties of DBS in the STN target could not be confirmed.