Hypoconnectivity of the Amygdala in Patients with Low-Back-Related Leg Pain Linked to Individual Mechanical Pain Sensitivity: A Resting-State Functional MRI Study

Abstract

Purpose

To explore resting-state functional connectivity (rsFC) of the amygdala in patients with low-back-related leg pain (LBLP).

Patients and Methods

For this prospective study, a total of 35 LBLP patients and 30 healthy controls (HCs) were included and underwent functional MRI and clinical assessments. Then, patients with LBLP were divided into acute LBLP (aLBLP) and chronic LBLP (cLBLP) subgroups. We further evaluated the between-group rsFC differences using left and right amygdala seeds in a whole-brain voxel analysis strategy. Finally, we performed correlation analysis between the rsFC values of altered regions and clinical indices.

Results

Compared to HCs, hypoconnectivity of the amygdala was observed in LBLP patients (P < 0.01, with correction). The amygdala’s rsFC pattern was different between aLBLP and cLBLP patients: decreased the amygdala’s FC to the right putamen, to the right paracentral lobule (PCL), or to the right posterior temporal lobe in aLBLP patients, while right amygdala to the bilateral anterior cingulate cortex (ACC) and the left postcentral gyrus (PoCG) in cLBLP patients. Correlation analysis showed that lower rsFC of the left amygdala to the right PCL was correlated with the von Frey filament (vF) test values of the left lumbar (p = 0.025) and right lumbar (p = 0.019) regions, and rsFC of the right amygdala to the left PoCG was correlated with lower vF test values of the left lumbar (p = 0.017), right lumbar spine (p = 0.003); to right PoCG was correlated with calf (p = 0.015); the rsFC of the right amygdala to bilateral ACC was negatively correlated with the pain rating index (p = 0.003).

Conclusion

LBLP patients showed amygdala hypoconnectivity, and the altered pattern of amygdala rsFC was different in the acute and chronic phases. Moreover, the amygdala hypoconnectivity was related to individual mechanical sensitivity (vF test) in LBLP patients.

Keywords:

• amygdala
• resting-state functional MRI
• low-back-related leg pain
• acute pain
• chronic pain

Acknowledgments

To all of the participants in this study, we express our sincere thanks. This study was supported by the National Natural Science Foundation of China (82160331), Jiangxi Province Double Thousand Talent Plan (jxsq2023201039), the Traditional Chinese Medicine Project of Jiangxi Province (2018A088), the General Project of Jiangxi Provincial Department of Education (GJJ190065) and the Natural Science Foundation of Jiangxi Province (20202BABL206114). This project is implemented by the Jiangxi Clinical Research Center for Medical Imaging. The funders had no role in the study design, data collection and analysis, the decision to publish or the preparation of the manuscript.

Disclosure

The authors report no conflicts of interest in this work.