Constant current or constant voltage deep brain stimulation: short answers to a long story.

Purpose: Recently, the feature of generating constant current output has been added to the implantable pulse generators (IPGs). The efficacy of the conventionally used constant voltage (CV) stimulation has been proved in different movement and psychiatric disorders. In this systematic review, we aimed to discuss the effect of constant current (CC) and constant voltage stimulation on patients with Parkinson's disease (PD) who had subthalamic nucleus deep brain stimulation implantation; we also compared these methods of stimulation with each other.

Methods: Using the words "Deep brain stimulation", "constant current" and "constant voltage", we developed a broad search strategy and a systematic search was conducted in PubMed, Scopus, Web of Science and Cochrane electronic bibliographic databases. Studies on the Parkinson's disease patients with subthalamic deep brain stimulation, which mentioned constant current or/and constant voltage setting stimulation were included.

Results: After screening of 284 articles, 10 reports were found eligible for this study. The score of unified Parkinson's disease rating scale part 3 was improved compared to the baseline, whether the stimulation was CV at baseline or CC. No significant change in non-motor outcomes was found.

Conclusions: Although CC stimulation has shown a significant improvement in both motor and non-motor symptoms of PD, switching from CV to CC did not result in a significant change in the score of these items based on UPDRS. To sum up, implantation of constant current devices is safe and significantly improves motor function; it also maintains an acceptable safety profile in patients with PD.