Background: It is still unclear whether dopamine (DA) levels correlate with Parkinson's disease (PD) severity or play a role in the mechanisms of high-frequency stimulation (HFS).
Methods: We have used microdialysis to record pallidal DA in 5 patients with PD undergoing microelectrode-guided pallidotomy.
Results: We found that patients with more severe disease and, consequently, lower pallidal DA did poorly after pallidal lesions. In the operating room, 4 of 5 patients had a significant increase in DA levels during HFS (600%, on average). To test the hypothesis that DA was important for the effects of stimulation, we correlated the amelioration in rigidity observed in the operating room with pallidal DA release. Though rigidity was 56% better during stimulation, no correlation was found between such an improvement and DA release.
Conclusions: These findings suggest that additional mechanisms not directly dependent on pallidal DA release may be involved in the clinical effects of HFS of the globus pallidus internus.
Keywords: Parkinson's disease; deep brain stimulation; dopamine; microdialysis; motor symptoms.
© 2013 Movement Disorder Society.