Functional connectivity in complex regional pain syndrome: A bicentric study

Area of Science:

• Neuroscience
• Medical Imaging
• Pain Research

Background:

• Complex regional pain syndrome (CRPS) exhibits inconsistent findings in brain imaging studies.
• Understanding functional and structural brain alterations in CRPS is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate functional connectivity (rsFC) alterations in the brains of CRPS patients using resting-state fMRI.
• To correlate imaging findings with clinical pain severity and somatosensory function in CRPS.
• To evaluate resting-state fMRI data quality in CRPS patients compared to controls.

Main Methods:

• Cross-sectional study of 51 CRPS patients and 50 matched controls from two centers.
• Resting-state functional connectivity (rsFC) analysis using predefined regions of interest (ROIs) and unconstrained ROI-to-ROI analyses.
• Evaluation of default mode network (DMN) connectivity and the degree rank order disruption index (k_D).

Main Results:

• Lower rsFC between the periaqueductal gray matter (PAG) and left anterior insula, and higher rsFC between the right sensorimotor thalamus and nucleus accumbens were observed.
• Pain intensity positively correlated with insulo-prefrontal rsFC, while tactile spatial resolution correlated with sensorimotor thalamo-cortical rsFC.
• No significant group differences in DMN connectivity or k_D were found; however, lower data quality was detected in CRPS patients.

Conclusions:

• Findings suggest potential down-regulated antinociceptive modulation by the PAG and increased reward system connectivity in CRPS pathophysiology.
• Novel findings from two independent cohorts highlight potential mechanisms, but data quality differences require cautious interpretation in future studies.