Associations of Regional and Network Functional Connectivity With Exercise-Induced Low Back Pain

Abstract

Musculoskeletal pain is an aversive experience that exists within a variety of conditions and can result in significant impairment for individuals. Gaining greater understanding of the factors related to pain vulnerability and resilience to musculoskeletal pain may help target at-risk individuals for early intervention. This analysis builds on our previous work identifying regions where greater gray matter density was associated with lower pain following standardized, exercise induced musculoskeletal injury. Here we sought to examine the relationship between baseline resting state functional connectivity in a priori regions and networks, and delayed onset muscle soreness (DOMS) pain intensity following a single session of eccentric exercise in healthy adults. Participants completed a baseline functional MRI scan and a high intensity trunk exercise protocol in the erector spinae. Pain intensity ratings were collected 48-hours later. Resting state functional connectivity from four seed regions and 3 networks were separately regressed on pain intensity scores. Results revealed that connectivity between left middle frontal gyrus, the left occipital gyrus and cerebellar network seeds and clusters associated with discriminative, emotional, and cognitive aspects of pain were associated with lower post-DOMS pain. Results suggest resilience to clinically relevant pain is associated with aspects of regional and network neural coherence. Investigations of pain modulatory capacity that integrate multimodal neuroimaging metrics are called for. PERSPECTIVE: Our results provide key support for the role of structural and functional coherence in regional and network connectivity in adaptive pain response and represent an important step in clarifying neural mechanisms of resilience to clinically relevant pain.

Keywords: Delayed onset muscle soreness; musculoskeletal pain; pain modulation; pain resilience; resting state functional connectivity.

Figure 1.

Clusters from Boissoneault et al where pain resilient participants had significantly higher GMD than pain susceptible participants in standard MNI space (p_FWE<.05). Red: Left medial frontal gyrus; Green: Left middle occipital gyrus; Violet: Left middle temporal gyrus; Blue: Left inferior frontal gyrus; Yellow: Left inferior frontal gyrus; Teal: Right superior frontal gyrus.

Figure 2.

(Upper Left) Anterior view showing the location and spatial extent of clusters (1) (coordinates: 36, −76, 0) including the right lateral occipital cortex, (2) (coordinates: −20, −52, 58) including the left superior parietal lobule and the left lateral occipital cortex, (3) (coordinates: 16, 14, − 16) including the right orbitofrontal cortex, where connectivity with the left middle frontal gyrus was associated with lower DOMS pain severity. (Right and Lower Left) Scatterplots 1 to 3 demonstrating the significant correlation between pain severity and functional connectivity of left middle frontal gyrus with each significant cluster.

Figure 3.

(Left) Left mid-sagittal view showing the location and spatial extent of a cluster (coordinates: −12, −68, −16), including the left cerebellum and left lingual gyrus, where connectivity with the left middle occipital gyrus was associated with lower DOMS pain severity. (Right) Scatterplot demonstrating the significant correlation between pain severity and functional connectivity of left middle occipital gyrus with this cluster.

Figure 4.

Right and superior views showing the spatial extent of the independent components analysis derived networks: (blue) cerebellar, (red) sensorimotor, and (green) default mode.

Figure 5.

(Left) Right mid-sagittal view showing the location and spatial extent of a cluster (coordinates: 66, −44, 36), including the right posterior and anterior supramarginal gyrus, right angular gyrus and the right parietal operculum cortex, where connectivity with the ICA-derived sensorimotor network was associated with greater DOMS pain severity. (Right) Scatterplot demonstrating the significant correlation between pain severity and functional connectivity of the sensorimotor network with this cluster.

Figure 6.

(Left) Superior view showing the location and spatial extent of a cluster (coordinates: −20, −34, 62), including the left postcentral gyrus and the left and right precentral gyrus, where connectivity with the cerebellar network was associated with lower DOMS pain severity. (Right) Scatterplot demonstrating the significant correlation between pain severity and functional connectivity of the cerebellar network with this cluster.