Brain Functional Alternations of the Pain-related Emotional and Cognitive Regions in Patients with Chronic Shoulder Pain

Abstract

Objective: Chronic shoulder pain (CSP) is a common health problem associated with shoulder dysfunction and persistent pain for many different reasons. However, the studies of pain-related functional brain regions in CSP have been poorly investigated. The main purpose of our study was to observe whether there are abnormal functional changes in brain regions in patients with CSP by using functional magnetic resonance imaging (fMRI).

Patients and methods: We compared the differences of brain regions between 37 patients with CSP and 24 healthy controls (HC) using regional homogeneity (ReHo) method. The patients with chronic shoulder pain and healthy controls were matched for age and gender. Brain regions which had abnormal ReHo values were defined as seed region of interests. The approach of seed-based functional connectivity (FC) was further performed to analyze the connectivity between the seeds and whole brain regions. The relationship between abnormal regions and current clinical pain was also evaluated.

Results: Compared to healthy controls, the patients with CSP showed increased ReHo values in the left middle temporal gyrus and decreased ReHo values in right orbitofrontal cortex (OFC). The seed-based analyses demonstrated decreased connectivity between the right OFC and right rectus, superior frontal gyrus in patients with chronic shoulder pain. However, a correlation between ReHo values and clinical characteristics in CSP patients was not found.

Conclusion: The observed results indicate that there are abnormal ReHo values in brain regions of patients with CSP, especially in the OFC and middle temporal gyrus. Our findings demonstrate that the experience of CSP patients may be mainly associated with cognitive-affective pain processing, rather than nociception.

Keywords: chronic shoulder pain; cognition; emotion; functional magnetic resonance imaging.

Figure 1

Medial views and axial medial views of significant changes in ReHo between chronic shoulder pain (CSP) group and healthy controls (HC) group. The hot color indicates that chronic shoulder pain (CSP) group had increased ReHo compared with healthy controls (HC) group. The cool color indicates that chronic shoulder pain (CSP) group had decreased ReHo compared with healthy controls (HC) group. Gaussian Random Field theory correction (GRF) correction with significant voxel level p<0.01 and cluster level p<0.05, Two-Tailed.

Figure 2

Group differences in seed-based functional connectivity. The seed was defined as the right orbitofrontal cortex. The cool color indicated decreased functional connectivity in the chronic shoulder pain (CSP) group compared with healthy controls (HC) group. Gaussian Random Field theory correction (GRF) correction with significant voxel level p<0.01 and cluster level p<0.05, Two-Tailed.