Metabolic network as an objective biomarker in monitoring deep brain stimulation for Parkinson‘s disease: a longitudinal study

Background: With the advance of subthalamic nucleus (STN) deep brain stimulation (DBS) in the treatment of Parkinson’s disease (PD), it is desired to identify objective criteria for the monitoring of the therapy outcome. This paper explores the feasibility of metabolic network derived from positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose in monitoring the STN DBS treatment for PD.

Methods: Two cohorts with PET imaging were recruited for this study. The cohort I, including 33 PD patients and 33 healthy controls (HCs), were used for the establishment of the PD-related metabolic network pattern (PDRP). The cohort II, including 9 PD patients underwent bilateral STN DBS surgery and 9 HCs, were followed longitudinally to investigate the PDRP expression in monitoring STN DBS. Moreover, the metabolic pattern was further analyzed using graphical network measures of inter-ROI connections within PDRP.

Results: The identified PDRP pattern in cohort I was characterized by relative metabolic increases in the putamen, pallidum, caudate, thalamus, cerebellum, pons and olfactory region, and by metabolic decreases in the posterior parietal-occipital cortices. PDRP expression was abnormally elevated in PD patients compared with HCs (P < 0.001). For patients in cohort II, a significant decrease in UPDRS (P = 0.001) and PDRP expression (P = 0.004) was observed 3 months after STN DBS treatment, while a rollback was observed in both UPDRS and PDRP expression (both P < 0.01) 12 months after treatment. The changes of PDRP expression mediated by STN DBS has a significant correlation with UPDRS improvement (r = 0.7412, P = 0.003). The graphical network analysis of PDRP shows increased connections 3 months after STN DBS treatment and a return 12 months post-treatment, which was quantitatively confirmed by the small-worldness coefficient.

Conclusions: The preliminary results demonstrate the potential of metabolic network expression as complimentary objective biomarker for the assessment and monitoring of STN DBS treatment in PD patients. In-depth insight into network alterations in cortico-striatopallido-thalamo-cortical neurocircuitry may provide additional information to support the optimization of STN DBS therapy.