RESUMO
BACKGROUND: Parkinson disease (PD) remains a common neurodegenerative disorder. Functional neurosurgery largely arose with the introduction of deep brain stimulation (DBS) as a potential option for PD unresponsive to medical management. Biomarkers are clinical and laboratory indicators of therapeutic success or failure. OBJECTIVE: To examine the current and published literature relating to the development and use of biomarkers in monitoring and determining the efficacy of DBS in PD. METHODS: The PubMed database was systematically searched using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for systemic reviews. Studies that examined current or potential biomarkers measurable after DBS were included. Articles from 1952 to date were examined. RESULTS: The initial search identified 49 articles. Thirty articles met the inclusion criteria. Articles were subdivided into those addressing biomarkers with proven clinical usefulness and potential biomarkers that have future application. CONCLUSIONS: Biomarkers have been identified that can help to determine the effect of DBS on patients with PD. Current studies show that there are measured differences in electrophysiologic oscillations, gene expression, neuropeptide levels, metabolic function, inflammatory activity, and others in the central nervous system after DBS in PD. Local field potential and ß-band analysis stand as the clinically proven biomarkers of choice for DBS in PD. Many of the identified changes noted could be implemented as clinically useful biomarkers through which DBS may be monitored. Future studies are needed to determine which noted physiologic changes are most appropriately used as biomarkers and in which contexts they are most helpful.