Abnormal spontaneous neuronal activity and functional connectivity in Parkinson's disease with chronic pain: a resting-state fMRI study

Abstract

Abstract Background: The neural basis of pain in Parkinson’s disease (PD) is poorly understood. This study aimed to explore the alterations of spontaneous neuronal activity and functional connectivity (FC) pattern in PD with chronic pain by amplitude of low-frequency fluctuation (ALFF)and functional connectivity (FC). Methods: A total of 41 PD patients with pain (PDP), 41 PD patients without pain (nPDP), and 29 matched pain-free normal healthy controls (NCs) were enrolled in the study. The non-motor symptoms questionnaire (NMSQ) and the visual analog scale (VAS) were applied to pain screening and pain severity assessment. ALFF and FC were measured by resting-state functional MRI (rs-fMRI). ALFF was applied to investigate regional cerebral activity, and FC was used to evaluate functional integration of the brain network. Results: Compared with nPDP patients, PDP patients showed increased ALFF in the right superior frontal gyrus (SFG), supplementary motor area (SMA) and left paracentral lobule (PCL), precentral gyrus (PrG), while decreased ALFF in the right putamen. Only the ALFF value of the right putamen was negatively correlated with the VAS score in the PDP patients. PDP patients showed diminished FC in the right putamen with the midbrain, anterior cingulate cortex (ACC), orbito-frontal cortex (OFC), middle frontal gyrus (MFG), posterior cerebellar lobe, and middle temporal gyrus (MTG), as compared with nPDP patients. Conclusion: This study does disclose that anomalous regional brain activity within the motor cortex and putamen, as well as aberrant functional integration of the putamen with multiple brain regions are involved in the neural mechanism of pain in PD patients.