BACKGROUND AND PURPOSE: In Parkinson's disease (PD) subthalamic nucleus deep 
brain stimulation (STN-DBS) improves motor function. Also an effect on the 
neurovascular coupling in motor cortex was reported due to a parallel activation 
of a subthalamic vasodilator area (SVA). To address this issue further we 
analysed neurovascular coupling in a non-motor area.
METHODS: Twenty PD patients selected for bilateral STN-DBS were investigated 
with functional transcranial Doppler (f-TCD) before and after surgery. 
Hemodynamic responses to visual stimulation were registered in left posterior 
cerebral artery (PCA) and analysed with a control-system approach (parameters 
gain, rate time, attenuation and natural frequency). To exclude autonomic 
effects of STN-DBS, we also addressed spectrum analysis of heart rate and of 
systolic arterial blood pressure variability, and baroreceptor gain. Findings in 
the PD group were compared with healthy age-matched controls.
RESULTS: PD patients showed no neurovascular coupling changes in PCA territory, 
compared to controls, and STN-DBS changed neither blood flow regulatory 
parameters nor autonomic function.
CONCLUSIONS: Improvement of vasoregulation in some motor cortical areas after 
STN-DBS might be related to an improved neuronal functional rather than 
indicating an effect on the neurovascular coupling or autonomic function.