PURPOSE: Disturbances of the autonomic nervous system are common in patients 
with Parkinson's disease (PD) but the effect of deep brain stimulation of the 
subthalamic nucleus on cerebrovascular reactivity is not entirely known.
METHODS: Seven patients in an advanced stage of the disease and seven healthy 
age-matched controls participated in the study, which took place after one night 
of drug withdrawal. Cerebral blood flow velocity was continuously monitored on 
both sides with transcranial Doppler ultrasound, and cerebrovascular reactivity 
(CR) was evaluated with the cold pressure test. The measurements were repeated 
and compared during the stimulation-on and -off phases.
RESULTS: The PD patients had significantly higher CR values in the 
stimulation-on than -off conditions (15.1% ± 6.9 versus 9.4% ± 6.2; p = 0.03). 
CR values were higher in controls than in patients in the stimulation-off 
condition (20.4% ± 12.5 versus 9.4% ± 6.2; p = 0.007) without a significant 
difference with the stimulation-on phase.
CONCLUSIONS: CR, evaluated by the response to the cold pressure test, is 
impaired in patients with advanced PD and improved by subthalamic nucleus.