A Positron Emission Tomographic Study of Subthalamic Nucleus Stimulation in Parkinson Disease

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Abstract
Background: Long-term high-frequency stimulation of the subthalamic nucleus (STN) improves akinesia in Par- kinson disease. The neural correlates of STN stimula- tion are not well understood. Positron emission tomog- raphy can be applied to the in vivo study of the mechanisms of deep brain stimulation. Objective: To study changes in regional cerebral blood flow as an index of synaptic activity in patients with Par- kinson disease with effective STN stimulation on and off during rest and movement. Methods: Eight patients with Parkinson disease who had electrodes implanted in the STN underwent 12 measure- ments of regional cerebral blood flow with water O 15 positron emission tomography at rest and during per- formance of paced freely selected joystick movements, both with and without STN stimulation (3 scans per experimental condition). Motor performance and reac- tion and movement times were monitored. Statistical para- metric mapping was used to compare changes in re- gional cerebral blood flow between conditions and differences in activation. Results: All patients showed improvement in reaction and movement times during scans with the stimulator on. As predicted, increases in activation of rostral supple- mentary motor area and premotor cortex ipsilateral to stimulation were observed when stimulation was on dur- ing contralateral movement (P,.001). Unpredicted ob- servations included decreases in regional cerebral blood flow in primary motor cortex at rest induced by STN stimulation. Conclusion: Stimulation of the STN reduces the move- ment-related impairment of frontal motor association ar- eas and the inappropriate motor cortex resting activity in Parkinson disease. Arch Neurol. 1999;56:997-1003
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